Altered expression of p53 and MDM2 proteins in hematological malignancies.

In order to define the possible role of the MDM2 gene in the pathogenesis of human leukemia, the expression of MDM2 protein was examined in samples of fixed-permeabilized peripheral blood (PB) or bone marrow (BM) cells of leukemic patients by using flow cytometry. The present study showed, that normal PB and BM cells expressed low levels of MDM2. Overexpression of this protein was more frequently found in leukemic cells, namely in samples of patients with advanced, than those in incipient clinical stage of disease at examination. Of the 34 leukemias tested in our laboratory 24 (70%) showed abnormal expression of the MDM2 protein. This include 8/12 (66%) ALL, 10/13 (76%) B-CLL, and 6/9 (66%) AML. Since MDM2 and p53 are functionally related and overexpression of MDM2 can abrogate wild (wt)-p53 tumor suppressive function, we examined simultaneously with MDM2 protein expression also the expression of both wt-p53 and mutant (mt)-p53 with two MoAbs (Ab5 and Pab240). As measured by flow cytometry only a small part of the observed wt-p53 protein was in true wt-conformation (Ab5+), while most was in mt-conformation (Pab240+), which could mean, that most of the p53 protein in the cells was not functional, as in its usual role as a suppressor of the cell cycle. The MDM2 positive cases were negative for p53 (Pab240-) in hematopoietic cells of patients with B- and T-ALL at diagnosis and in relapsed disease. Samples of patients in remission with immunophenotype of normal cells were p53 and MDM2 negative. The expression of Ki67 antigen a nuclear protein associated with cell proliferation was used to verify the proliferative activity of the leukemic cells. Results of the two-color flow cytometric assay, which allows better definition of pathologic cell populations and nuclear fluorescence data for p53, MDM2 or Ki67 on a population of cells expressing only a given surface blast marker, confirmed their coexpression in the same cell. Our preliminary results supported the view that the expression of p53 is very probably involved in the regulation of leukemic hematopoiesis and that the inhibition of p53 expression could modulate the proliferation of leukemic cells. It appears, that MDM2 overexpression, which may be p53-dependent, or also p53-independent plays an important role in leukemogenesis and/or disease progression.

P53 protein expression in human leukemia and lymphoma cells.

The purpose of this study was to determine the value of p53 protein overexpression in human leukemia and lymphoma cells. We examined PB and/or BM samples on a series of 111 patients with immunophenotypically defined hematological malignancies at diagnosis, in remission and in relapsed disease comparing to 20 control samples of healthy individuals. p53 protein has been studied by flow cytometry using three monoclonal antibodies specific for epitopes on N-terminus (Bp53-12, DO-1) and central region (DO-11) of p53 protein. Our findigs showed, that p53 expression may contribute to phenotype of leukemic cells and that overexpression of this protein is often associated with progression of disease. All samples of early B-ALL patients and samples of patients with immunophenotypically defined T- cell disorders examined at diagnosis of disease were p53 positive. Eleven of 19 patient samples from AML at diagnosis showed also increased expression of p53 protein. The cells of all patients who responded to therapy with complete immunophenotypically defined remission were p53 negative. Relapsed T-, B- ALL and AML develop p53 alteration. We reported positive p53 expression in cells of patients with advanced stages of CLL in comparison to them with initial stage of disease at examination. As well as in the group of B- cell lymphomas only samples of patients with generalized FCC lymphoma at diagnosis were p53 positive. We detected p53 positive cells in immunologically defined myeloid blast crisis of CML opposite to p53 negativity in chronic phase of disease. The finding of p53 positive BM cells without immunophenotypic blast markers in two of followed cases documented the contributing value of p53 detection in their characterization. On the basis of above findings we conclude, that cytofluorometric determination of p53 expression may contribute to the better definition of leukemic phenotype. Loss of the normal p53 function may be important in the genesis of some leukemias. Elucidation of the mechanisms of p53 inactivation needs some more study.

Aberrant markers expression in T- and B-lymphoid and myeloid leukemia cells of different differentiation stages.

The aim of the study was to ascertain if in T acute lymphoblastic leukemia (T-ALL), B acute lymphoblastic leukemia (B-ALL) and acute myeloid leukemia (AML) of different differentiation stages the coexistence of aberrant markers correlate with the degree of leukemic blasts maturation. We evaluated the results of surface and intracellular markers in 42 T-ALL, 86 B-ALL and 71 AML cases. A large panel of monoclonal antibodies (MoAbs) against T-cell, B-cell, myeloid cell and non-lineage specific structures has been used. Patients had dual-color flow cytometric immunophenotyping performed by FACStar flow cytometer. The correct immunological diagnosis of followed new cases before any treatment has been performed and simultaneously the presence of atypical/aberrant phenotypes has been studied and correlated with leukemia cells differentiation stage. A great deal of T-ALL and AML, in opposite to B-ALL cases, revealed a high proportion of atypical phenotypes (55, 75 and 36%, respectively), which are absent in nonleukemic cells. We found out that these atypical phenotypes were present in T-ALL, AML (not clearly in B-ALL) through all differentiation stages and so we obtained an evidence that they might represent an abnormal/atypical rather than an immature phenotype, as it was postulated till now by several authors.

Flow cytometry of p53 protein expression in some hematological malignancies.

p53 is a tumor suppressor gene encoding a nuclear phosphoprotein that plays an important role in the control of normal cell proliferation. We have tried to establish the value of the p53 protein expression in peripheral blood (PB) and/or bone marrow (BM) cells of patients with some hematological malignancies. A recently developed fixation/permeabilization method was modified for flow cytometric assessment of p53 protein expression using two anti-p53 monoclonal antibodies. p53 quantitation expressed as molecules of equivalent soluble fluorochrome per cell (MESF) providing valuable data contributing to a more precise definition of leukemic cells, was also applied. Our findings showed higher percentage of p53 expression in cells of AML patients at the time of diagnosis opposite to the controls. These data, in association with immunophenotype of cells, accompanied diagnosis of relapse or definition of remission after allogeneic BM transplantation. We observed also elevated levels of p53 protein at initial diagnosis of early B-ALL. According to our results quantitation of p53 protein allows better characterization of selected population of BM cells and should be used for the monitoring of blast persistence during and after therapy and might also be one of the methods to indicate early relapse. Percentage of p53 protein positivity varied in our group of B-CLL patients tested in connection with progression of disease. We documented also one case of Burkitt's lymphoma with high percentage of p53 positivity. Measurement of p53 protein expression by flow cytometry may be of clinical importance by indicating levels of positivity. Our results suggest, that p53 alteration is frequently involved at initial diagnosis of AML, in some T-cell disorders and on the contrary more frequently during early B-ALL relapse, in advanced stages of B-CLL and in Burkitt's lymphoma. p53 protein quantitation is of value to ascertain malignancy and provides additional parameter suitable for the evaluation of residual disease and for the monitoring of therapy.

The relationship of HLA-DR, CD38 and CD71 markers to activation, proliferation and differentiation of some human leukemia and lymphoma cells.

We investigated the expression-percentage as well as MESF values ("molecules of equivalent soluble fluorochrom" that represent approximately the density of marker expression) of HLA-DR, CD71 and CD38 markers in some human leukemias (ALL, AML, CLL, CML) and lymphomas. They are non-lineage restricted and are supposed to be activation markers except for cases where they represent pathological phenotype like HLA-DR in pre B-ALL, CD38 in some M0 AML or in plasmocytoma or CD38 and CD71 in less mature T-ALL. We used flow cytometry, immunofluorescent staining, DNA staining by propidium iodide and quantification by calibration particles. We demonstrated increased MESF values of HLA-DR compared with controls in all investigated disorders, what could have a prognostic value. We demonstrated significantly higher MESF values of HLA-DR in cALL (37,300-46,000) in comparison with AML (9400-12,400), what could represent another important parameter when distinguishing between these two groups of leukemia. In cells of CML patients with lower CD38% and CD71% increased MESF values (5100 for CD38 and 7900 for CD71), were found while in some T-ALL, AML and cALL patients with high percentages of CD71 and CD38 there were lower MESF values what could indicate a possible connection of higher stage of cell maturation with increased density of CD38 and CD71 markers. We investigated possible relationship between percentage of expression of HLA-DR, CD38 and CD71 and proliferation rate by DNA analysis of the cell cycle. In a group of non-Hodgkin's lymphoma patients, there was no significant increase of proliferation index of malignant cells compared with control. The correlation between percentage of expression of mentioned parameters and proliferation index was not significant. In one patient with Burkitt's lymphoma we demonstrated significant increase of proliferation index of CD71+ subpopulation compared with CD71- one, what indicates that in aggressive form of NHL CD71 can be evaluated not only as activation but also as proliferation marker.

Phenotypic heterogeneity and aberrant markers expression in T-cell leukemia.

For exact determination of lineage assessment there is a need of surface membrane and intracellular (cytoplasmic and nuclear) immunophenotyping performed by flow cytometry. We evaluated in detail the results of surface and intracellular immunophenotyping of 34 T-ALL cases. The great heterogeneity of T-cell differentiation markers has been observed which did not allow relevant subclassification of T-ALL according to the existing subclassification schemes and the proposed three-stage model of physiological T-cell differentiation. Therefore, a simplified classification based on the CD3 marker expression either on cell membrane or in cytoplasm has been created with allocation of T-ALL into two main phenotypic groups. From 34 in detail examined T-ALL cases a great deal-27 (79%) belonged to an immature phenotype (Stage I) and only 7 (21%) expressed more mature phenotype (Stage II). Simultaneously the presence of atypical/aberrant T-cell phenotypes has been studied. We showed that in T-ALL it was possible to specify some cases with leukemia-associated phenotype with coexistence of atypical markers which are absent in nonleukemic cells. In a majority of cases early B-lineage marker (CD10) and in a smaller proportion of them non-lineage associated marker (CD34) were observed. Myeloid marker CD13 was observed in one case of the immature T-ALL, together with CD10 and CD34. As these atypical markers were present through all differentiation stages of T-ALL we obtained a strong evidence that they might represent an abnormal rather than an immature phenotype. The prognostic significance of T-ALL subtypes and aberrant markers coexpression have been discussed. Simultaneously it was shown that quantitative immunofluorescence could provide an additional important diagnostic marker also in T-ALL cases.

Intracellular markers in acute myeloid leukemia diagnosis.

In our study we used a new proposed system of CD45 monoclonal antibody in combination with the side scatter (SSC) parameter as a very useful gating method allowing myeloblast detection especially in cases with low blasts percentage in examined samples. Immunological demonstration of myeloperoxidase (MPO) in the cytoplasm of AML blasts is considered to be a reliable and highly sensitive marker. Using a direct single and double immunofluorescence staining method and flow cytometry we evaluated the intracellular expression of two granular constituents of myeloid cells--MPO and lactoferrin (LF) in leukemia cells from 18 patients at AML diagnosis, two patients in remission after allogenic bone marrow transplantation and in six controls. Two different fixation/permeabilization techniques were used: Fix&Perm, paraformaldehyde and saponin prior to monoclonal antibody staining in order to verify the sensitivity of two labeling methods for MPO. Although both reagents used in this study proved to be efficient tools for the fixation and permeabilization of leukemia cells, the second one was characterized by higher sensitivity in detection of MPO. By double staining of MPO and LF we were able to distinguish undifferentiated cells from the granulomonocytic maturation compartments in bone marrow, since LF is proposed to be selectively expressed from the myelocyte stage of differentiation onward. Cytoplasmic CD13 expression was detectable in AML blasts after their buffered-formaldehyde-acetone fixation/permeabilization. According to our results the detection of MPO and CD13 markers in the cytoplasm of leukemia cells is of great importance in the definition of FAB M0-M1 subtype of AML. Furthermore we described overexpression of CD34 antigen in AML and revealed the characteristic marker combination when CD34 was studied simultaneously with MPO. This finding also coincided with some atypical phenotypic features (CD15/MPO, CD7/cCD13, CD2/cCD13, CD33/cCD13, MPO/cCD13) contributing to the differential diagnosis and allowing the immunologic monitoring of patients for the presence of residual disease.

Quantitative immunocytofluorometry--new parameters for the definition of leukemia cells.

In our study we used for definition of leukemia/lymphoma cells a new parameter which allows the enumeration of mean fluorescence intensity expressed by the number of antigen molecules per cell. Quantitative immunofluorescence using calibration microbeads was performed in 36 patients with different acute and chronic lymphoid and myeloid leukemia and in 19 healthy volunteers. We showed that quantitative immunophenotyping allowed the definition of aberrant marker densities on neoplastic cells. We demonstrated under- and overexpression of CD8 marker in CD3/CD4/CD8 complex in T acute lymphatic leukemia and T non-Hodgkin's lymphoma and T leukemia of large granular lymphocytes as compared to normal counterparts. We pointed out that certain antigens (e. g. CD10, CD4, CD24) were expressed at different levels on different cell subsets (CD10 in early B-acute lymphatic leukemia and coexpressed in T-acute lymphatic leukemia, CD4 on T cells and monocytes, CD24 on B cells and granulocytes in chronic myeloid leukemia). We showed that quantitative immune fluorescence could provide new data contributing to a more precise definition of cell differentiation. We documented the significant difference between antigen density of early and late markers in B-cell and myeloid malignancies. Further, we demonstrated that quantitative immune phenotyping could help in determination of exact definition of pathologic clone in morphologically immature leukemia population and showed that parameters of this method are also convenient for cytoplasmic marker evaluation. In our study we were able to demonstrate that CD45 quantitative expression appeared to be a more informative parameter than its percentage of antigen-positive cells as a measure of antigen expression only and we pointed out that low and high CD45 densities enabled to differentiate between pathological clone and residual healthy population in examined sample. We showed that quantitative immune phenotyping could be another important parameter for definition of leukemia phenotype suitable for detection of minimal residual disease.

Leukemia-associated phenotypes: their characteristics and incidence in acute leukemia.

Leukemia-associated phenotypes have been suggested to be a valuable tool for the detection of minimal residual disease in acute leukemia patients, as they allow to distinguish leukemic blasts from normal hematopoietic progenitor cells. The aim of the present study was to analyze the proportion of acute leukemia patients (both with lymphoid and myeloid leukemias) in which the immunological detection of leukemia-associated phenotypes was convenient for the distinction of leukemic and normal cells. For this purpose we have studied the blast cells from 186 acute leukemia patients at diagnosis with a large panel of monoclonal antibodies by flow cytometry using double staining combinations. From aberrant phenotypes on blast cells we followed lineage infidelity (coexpression of myeloid markers in lymphoid leukemia cells and vice versa, as well as the simultaneous expression of both, T and B cell markers in one lymphoid blast cell) and asynchronous marker expression (simultaneous expression of early and late markers in one cell). One hundred and five of the 186 acute leukemia cases analyzed (56%) showed the presence of leukemia-associated phenotypes. In 41 of the 90 ALL cases followed (46%) and in 40 of the 96 AML cases studied (42%) lineage infidelity was observed. Asynchronous antigen expression was detected in 24 followed cases (13%). Evaluation of the cell marker density by means of calibration microbeads demonstrated abnormal mean channel immunofluorescence and molecules of equivalent soluble fluorescein for CD8 in two patients with T cell malignancies at diagnosis. Abnormal CD8 density might thus represent a characteristic feature of malignant CD8-positive T cell clone. Quantitative marker evaluation therefore seems to be another important mean for the detection of aberrant phenotypes on leukemia cells suitable for the detection of minimal residual disease.

Some early differentiation markers detected in cytoplasm of pre-B cells by flow cytometry.

Immunofluorescent staining of cytoplasmic IgM (heavy chains) and CD24 as well as their simultaneous staining with surface B cell markers was used to study immunophenotype changes in B cell differentiation. Human hematopoietic B cell lines P3HR1 and RAJI were used. We found that IgM and CD24 cell markers while absent on cell membrane could be detected in their cytoplasm (c). The presence of cIgM in cell lines RAJI, P3HRI indicates their early pre-B differentiation stage. The presence of cCD24 simultaneously with mCD22 and cIgM is the evidence that hematopoietic cell lines or leukemias may not accurately reflect normal differentiation pathway. Combinations of cIgM, cCD24 with surface B cell markers CD10, CD19 on these cell lines can be considered as leukemia associated phenotypes. Some of them were shown in bone marrow and peripheral blood of pre-B ALL and B-CLL patients and can be used for the detection of minimal residual disease. Different fixation/permeabilization methods were tested in order to choose the optimal one for simple detection of cytoplasmic markers or their simultaneous detection with surface markers by flow cytometry. They included "one-component-methods" (methanol-M, saponin-S), methods combining these components with paraformaldehyde (P+M, P+S) or buffered formaldehyde acetone (BFA). The choice depended on individual marker detected. General parameters like the proportion of debris, cell aggregation, cell loss and the changes of scatter parameters FSC and SSC were taken into consideration. The priorities of combined methods P+S, P+M1 and BFA over one-component methods are demonstrated.

Flow cytometric detection of some activation and proliferation markers in human hematopoietic cell lines.

Simultaneous surface marker/DNA, cytoplasmic/DNA or nuclear/DNA staining was used to study proliferation of hematopoietic cell lines (MOLT4, BJAB, P3HR1). Different fixation/permeabilization methods (paraformaldehyde with metanol or Tween 20 or saponin, buffered formaldehyde-acetone) were used providing optimal results of the double stainings. There was a significant increase of S phase and proliferation index (PI) of CD71+ and Ki67+ MOLT4 cells in comparison with their negative counterparts. This indicates their close connection with proliferation. Unlike that, the correlation between the expression of CD38 and S phase or PI was not significant either in MOLT4 or in P3HRI cells. For cytoplasmic markers CD3 (in MOLT4 cells) and CD22 (in BJAB cells) statistically significant (cCD3) and not significant (cCD22) correlation was demonstrated between their expression and S phase or PI. Molecular equivalents of soluble fluorescein values for CD71 were always higher than for CD38. The density of these cell surface markers in addition to the percentage of their expression is of considerable significance for their evaluation as activation or proliferation markers.

Immune phenotype and some enzyme patterns in phorbol ester-induced chronic lymphocytic leukemia cells.

Leukemic cells from 10 patients with B-chronic lymphocytic leukemia (B-CLL) were isolated and cultured in the presence of 12-0-tetradecanoylphorbol 13-acetate (TPA) at a concentration of 8 x 10(-7) mol for 72 hours. Cells were analyzed before cultivation and after 72 h of cultivation with and without TPA for changes in surface membrane (Sm) and cytoplasmic (cyt) markers expression, presence of receptor for mouse rosette forming cells (MRFC) and some enzyme profiles. All B-CLL cases studied showed typical B-cell phenotype. TPA treatment induced hairy cell leukemia (HCL) characteristics, given by the membrane CD22 and CD25 expression and TRAP positivity in the majority of the cases tested. Cells had hairy cell-like morphology with more intensive cytoplasmic immunoglobulin (CIg) fluorescence staining, absent receptor for MRFC and increased activity of purine nucleosidephosphorylase. In common these changes indicate that TPA can induce hairy cell characteristics on B-CLL cells in vitro suggesting the more mature differentiation stage of HCL compared with CLL. Furthermore, we originally demonstrated that the CD22, present in the cell membrane after TPA, could be detected in the majority of unaffected B-CLL cells in their cytoplasm. From the technical point of view some intracellular CD markers and Igs of B-CLL cells in viable cells in suspension assayed by flow cytometry are described in this study.

Human hematopoietic cell lines: a model system for study of minimal residual disease detection technique in acute leukemia.

Double immunofluorescence studies using both surface and cytoplasmic antigens were performed on cells of some human hematopoietic lines. We tested several permeabilization protocols in order to optimize, improve and simplify flow cytometric assay to detect the combinations of two markers present in one cell which could be regarded as leukemia-related markers. It was found, that buffered formaldehyde-acetone (BFA) fixation renders the cell membrane permeable without destroying surface antigens so that intracellular and cell surface markers could be measured simultaneously by flow cytometry. Cell lines used for the experiments reported here included MOLT4 T cell line, mature B cell lines DAUDI and U-266, and early B cell line REH-6. Results from our studies demonstrated, that in the absence of CD3 antigen on the surface membrane of viable MOLT4 blast cells, double labeling of fixed, permeabilized cells revealed 97% mCD7+, cCD3+ double positive cells. Two color staining with anti-CD19 and anti-CD22 monoclonal antibodies (MoAbs) in DAUDI cells showed, that larger part of cCD22+ cells expressed mCD19 antigen. CD22 antigen was absent on DAUDI cell membrane. Of great interest was the finding, that the marker detected by anti-CD19 MoAb which was absent on the membrane of U-266 cells was detected in their cytoplasm. Double staining of these cells revealed, that the number of mCD22+, cCD19+ double positive cells was 80%. Cytoplasmic CD22 antigen along with surface membrane CD19 was used to define early B cell line REH-6 as well. Our results demonstrate majority of double positive cells among tested population (mCD19+, cCD22+). To our knowledge the presence of cytoplasmic IgM detectable by flow cytometry in REH-6 cells, which could be so regarded as a precise and adequate counterpart to pre-B acute leukemia cell phenotype in children, is an original finding. Immunological typing plays an important part in the multiple marker analysis of hematopoietic malignancies. Through these surface and cytoplasmic marker combinations minor neoplastic cell populations could be detected. Human hematopoietic cell lines could serve as a reliable model system for monitoring minimal residual disease in acute leukemia patients.

Evaluation of different fixation-permeabilization methods for simultaneous detection of surface, cytoplasmic markers and DNA analysis by flow cytometry in some human hematopoietic cell lines.

Different fixation/permeabilization methods were investigated for their convenience for simultaneous detection of membrane marker/DNA staining or cytoplasmic marker/DNA by flow cytometry. Nine different methods were employed. The expression of membrane marker CD20 and cytoplasmic marker CD22 on BJAB and DAUDI cells and cytoplasmic CD3 on MOLT4 cells were measured. Optimal methods were those that combine paraformaldehyde and saponin (for membrane CD20/DNA staining and cytoplasmic CD3/DNA staining) or buffered formaldehyde-acetone (for membrane CD20/DNA staining and for cytoplasmic CD22/DNA staining). Special interest was focused on proliferation marker CD71 and nuclear antigen Ki67. We investigated CD71 in MOLT4 cells and Ki67 in MOLT4, DAUDI and BJAB cells. Both of these markers are closely associated with proliferation rate. The optimal method for detection of Ki67/DNA staining combines paraformaldehyde with Tween 20.

Flow cytometric determination of leukemia-associated marker combinations for the study of minimal residual disease.

To study the minimal residual disease in acute leukemia patients we used some marker combinations related either to the simultaneous surface membrane and cytoplasmic marker expression, or to the expression of atypical marker combinations, that are absent or extremely rare in normal hematopoietic cells. We investigated to which extent flow cytometric analysis of leukemia-associated marker combination may contribute to sensitive follow-up in patients with acute leukemia. For this purpose dilution experiments were performed, in which artificial mixtures of normal peripheral blood lymphocytes and leukemia cells from a patient with leukemia-associated phenotype were prepared and analyzed for double positive cells. Our results showed that the sensitivity of double color immunofluorescence assay was 3 in 10(4) cells. Sequential studies of residual disease were evaluated in five acute leukemia patients with leukemia-associated markers combinations at diagnosis. In three of them morphologic relapse was preceded by the immunologic detection of small amounts of leukemia cells, while in two other cases, in which no double positive cells for leukemia-associated markers were found, patients are still in hematologic remission. This approach to the study of minimal residual disease could be valuable in monitoring the efficiency of chemotherapy, as well as in evaluating the quality control of bone marrow before autografting. Furthermore, flow cytometric approach can efficiently complete other methods, which are used for more exact definition of remission in acute leukemia patients.

Cytoplasmic and surface membrane phenotypic markers in cells of B cell chronic lymphocytic leukemia.

Peripheral blood cells of twenty-six patients with B cell chronic lymphocytic leukemia (B-CLL) were characterized for their surface membrane and cytoplasmic marker profiles using flow cytometry and fluorescence microscopy. According to surface membrane marker analysis three distinct immunophenotypic subgroups of B-CLL were identified: group I (SIg+, MR+, CD5+, B Ag+, T Ag-; 19 cases), group II (SIg+, MR+, CD5+, B Ag+, TAg+; 3 cases), group III (SIg-, MR+, CD5+, B Ag+, T Ag-; 4 cases). Cells from all patients were positive for the CD19 antigen and at least one of other B cell antigens. Cells from all patients expressed also CD5 and HLA-DR antigens and formed mouse rosettes (MR). Great heterogeneity was found in the membrane and cytoplasmic marking by anti-CD22 MoAb. In four of 23 patients tested, CD22 antigen was expressed in the cytoplasm of CLL cells while it was absent on surface membrane of these cells. This finding was discussed from the point of certain cell heterogeneity in the followed B-CLL cases. Cytoplasmic immunoglobulin (CyIg) detection showed to be very important especially in group III of followed B-CLL cases with undetectable surface immunoglobulins (SIg). Cytoplasmic antigens and immunoglobulin determinations are useful in phenotyping every B-CLL patient, as well as in the immunological study of different maturation stages of B lymphocytes.

Detection of cytoplasmic and surface membrane markers in cells of some human hematopoietic cell lines.

The cells of some human leukemia-lymphoma T cell lines (JURKAT, MOLT4), B cell lines (DAUDI, U-266) and of myeloid U-937 cell line were characterized for their surface membrane and cytoplasmic marker profiles. The usefulness of some fixation and permeabilization methods of cell membrane for detection of cytoplasmic markers by flow cytometry was studied. The methods of cell fixation in suspension were found to be more sensitive than the methods of cell fixation in smears. With the very short buffered formaldehyde-acetone (BFA) fixation used in this study an optimal penetration of the monoclonal antibodies (MoAbs) through the plasma membrane and specific binding to the appropriate structures were achieved. CD22 antigen was detected in cytoplasm but not on membrane of DAUDI cells. In another B cell line, U-266, CD22 antigen was present both in cell membrane and cytoplasm. The marker corresponding to anti-CD19 MoAb was detected in cytoplasm but was absent on membrane of U-266 cells. Furthermore, the antigen estimated by anti-CD3 MoAb could be detected intracellularly in cells of both T cell lines tested, while it was absent on cell membrane of these cells. The phenotypic study of U-937 cells showed that the majority of cells expressed myeloid associated antigens. In our study the CD14 marker detected on cell surface membrane of U-937 cells was missing in their cytoplasm. The surface antigens remained intact after BFA fixation enabling a simultaneous detection of membrane and cytoplasmic markers in double immunofluorescence studies. Through this combination of markers minor cell populations could be detected. Human hematopoietic cell lines could serve as a reliable model system for a rapid and quantitative immunodiagnosis.

Purine metabolism enzyme pattern, cytochemical characteristics and clinicopathologic features of CD10-positive childhood T-cell leukemia.

Purine metabolism enzyme pattern, cytochemical markers and clinicopathologic features of common acute lymphoblastic leukemia antigen (cALLA; CD10)-positive, CD10-negative T acute lymphoblastic leukemia (ALL), and cALLA-positive non-T, non-B ALL (common ALL; C ALL) of children were compared. The results of immunophenotyping of blast cells in 61 children with ALL who were treated and followed during the last 7 years at the Second Pediatric Clinic in Bratislava are presented. The aim of our study was to determine the correlation of CD10 marker expression with purine enzyme activities and clinical course in ALL of children. Immunologic phenotype performed by a panel of monoclonal antibodies in indirect immunofluorescence assay revealed 3 main ALL groups: Common ALL (C ALL), T ALL and CD10+ T ALL (C + T ALL). An additional exact cytochemical marker analysis was performed in these three ALL immunologic subtypes. Two enzymes of purine metabolism, i.e. adenosine deaminase (ADA) and purine nucleosidephosphorylase (PNP) were investigated in blast cells by paper radiochromatography. Life-table analysis revealed significant prognostic differences with regard to event-free survival and overall survival in followed groups of ALL patients. Our results showed a rather high frequency of mixed (C + T) ALL phenotype. The characteristic T ALL enzyme pattern (high ADA, low PNP) was present not only in T, but also in CD10+ T ALL blast cells. The T cell marker showed to be dominant in the determination of clinical course and prognostic significance in children with ALL; children with T and CD10+ T ALL phenotype, in contrast to C ALL phenotype, experienced more frequent relapses and a shorter event-free survival.

[Immunologic parameters in patients with malignant melanoma]. / Sledovanie niektorých imunologických parametrov u pacientov s malígnym melanómom.

In an attempt to better define the immunological reactivity of patients with malignant melanoma, the electrophoretic mobility of lymphocytes and their reactivity were studied in poly-L-lysine agglutination and in nucleolar test. Blood samples were examined before treatment and repeatedly after surgical removal of the tumor. A microagglutination test induced by poly-L-lysine was used for the detection of sensitized lymphocytes in peripheral blood of melanoma patients. The number of positive results was increasing with the progression of the disease. After incubation with poly-L-lysine the electrophoretic mobility of lymphocytes was changed in melanoma patients. The nucleolar test was used for the study of quantitative and morphological changes of the nucleoli in lymphocytes. Elevated values of the nucleolar coefficient and an increased number of active nucleoli provided evidence on the higher immunological reactivity of melanoma patients. The decline in the number of lymphocytes with ring-shaped nucleoli, signaling immunologic exhaustion, are of prognostic value. Lymphocytes were assayed also for the presence of receptors for sheep erythrocytes (E active and total rosettes) and C3d component of complement (EAC rosettes). The reported findings may be used to advantage in evaluating the immunological reactivity of melanoma patients.

Kinetics of some immunological and biochemical changes of immunocompetent cells during tumor growth in rats.

The dynamics of lymphocyte response in peripheral blood, the tumor draining lymph node, spleen and thymus, was followed in a model system of syngeneically transplanted rat MC-1 tumor. Electrophoretic mobility (EPM) of lymphoid cells was determined by the automatic mode of measurement. The results revealed a two-phase pattern of EPM changes during the course of cancer growth. The first phase (day 3 to 6 following intramuscular injection of tumor cells) was characterized by a prevalence of high-mobility cells, while in the second phase (day 14 to 20), depletion of high-mobility cells was compensated for by an increased number of low-mobility cells. The mean EPM value was found to be increased only in the thymus at that time. Changes in the adenosine deaminase activity proved to be most expressive in the tumor draining lymph node and in the second phase also in splenic and thymic lymphocytes. An increased percentage of active lymphocytes with compact nucleoli with nucleolonemas became evident already on the 3rd day in all the lymphoid organs followed. The response was two-phasic only in the lymphocyte population of the peripheral blood, while their percentage in the other organs remained higher even on day 20. Changes in the proportion of high- and low-mobility cells in the lymphoid organs followed here, in correlation with the adenosine deaminase activity and the percentage of active lymphocytes, were interpreted as a response of immunocompetent cells in animals with a growing tumor.