Alterations in IRF1/IRF2 expression in acute myelogenous leukemia.

The interferon response genes 1 and 2 have been shown to be involved in the regulation of differentiation and proliferation of cells of the myeloid series, with the former functioning as an anti-oncogene and the latter as an oncogene. In the study described here, the levels of expression of these two genes and the ratio of their expression were compared in AML and normal marrow. The ratio of gene expression was significantly less in AML marrow cells as compared to normal marrow cells [med ratio = 1.33 vs. 2.97, P = 0.003]. While the expression ratio was unaffected by the presence or absence of either ras or fms mutations, p53 mutations were associated with higher IRF1:IRF2 expression ratios that wt p53 genes [med = 1.701 vs. 1.135, P = 0.014]. Given the functional characteristics and the competitive nature of these two genes, it is possible that leukemic transformation is associated with a fall in IRF1:IRF2 ratios. Finally, the administration of IL4 can result in the normalization of the IRF1:IRF2 ratio in the marrow cells of some patients with AML.

Quantitation of interferon regulatory factor transcripts in patients with acute myeloid leukemia.

Interferon regulatory factors IRF-1 and IRF-2, the two mutually antagonistic factors, fluctuate during the cell cycle and play an important role in normal and neoplastic growth processes. The relative levels of these two transcripts were analyzed in 5 normal and 43 acute myeloid leukemia (AML) bone marrow (BM) specimens by a semiquantitative RT-PCR method. IRF-1 and IRF-2 cDNA sequences were coamplified using primers that were designed to span regions of high homology between the genes. Each primer can anneal equally to both IRF-1 and IRF-2 sequences. Hence, the relative amount of amplified products from each cDNA species provides an estimation of proportional concentration of the RNA transcripts in the test sample. Results indicate expression of both the transcripts on all the leukemia and lymphoma cell lines tested, normal and AML BM. Significantly higher IRF-1:IRF-2 ratio was observed in normal as compared to AML BM (p = 0.007). There was no correlation with clinical factors such as FAB subtype. A single dose of amifostine or three daily doses of recombinant IL-4 were administered to 5 and 8 AML patients, respectively. The changes in the expression of these transcripts were studied prior to administration of the agent (d0) and after 3 days (d3). IL-4 treatment showed significant increase in the IRF-1:IRF-2 ratio in 4 of 8 patients (p = 0.05); amifostine treatment did not show any appreciable change.

Intra-tumoral cytolytic cells: pattern of distribution in B-cell non Hodgkin s lymphoma.

Non-Hodgkin s lymphomas (NHLs) constitute a heterogeneous group of lymphoid neoplasms and a majority of them in India are of B-cell phenotype. Varying numbers of T lymphocytes and natural killer (NK) cells are consistently present within the lymph nodes (LNs). The role of these reactive cells is becoming understood. TIA-1 is a cytotoxic granule associated RNA binding protein, the expression of which is restricted to cytotoxic T lymphocytes (CTLs) and NK cells. Snap frozen lymph node biopsies obtained from 41 B-cell NHLs were localized for intra-tumoral TIA-1 + cytolytic cells by immunohistochemistry. Distribution of T cell subsets and NK cells were also quantified. Cells expressing TIA-1 antigen was observed in all the cases, seen as a strong granular cytoplasmic signal. Results indicate significantly higher number of TIA-1 cytolytic cells outside (periphery of the follicle and interfollicular areas) than within the neoplastic follicle in follicular lymphomas (p<0.001). In small lymphocytic lymphomas, cytolytic cells were mainly seen as uniformly scattered single cells, distributed throughout the tumor environment. In mantle cell and diffuse large B-cell lymphomas these were most often seen as small clusters and less frequently as singly scattered cells. Higher numbers of CD4 + than the CD8 + T cells were observed in most cases. Contrary to the follicles in follicular hyperplasia, CD57 + NK cells were predominantly observed outside the neoplastic follicle in follicular lymphomas (FLs). These results outline specific interactions between the potential anti-tumoral cytolytic and the malignant cells of B-cell NHLs.

Expression of adhesion molecules in B-cell chronic lymphocytic leukaemia: an analysis in lymphoid compartments--peripheral blood, bone marrow and lymph node.

The trafficking or homing of different lymphoid subsets to particular microenvironment is mediated by specific cell adhesion molecules (CAMs) expressed on lymphocytes and endothelial cells. B-cell chronic lymphocytic leukaemia (B-CLL) or Non-Hodgkin's lymphoma of small lymphocytic, B-cell type are monoclonal expansions of mature lymphocytes. The relative distribution of the tumor lymphocytes among various lymphoid compartments vary from patient to patient. Very few studies underlying this issue are available. To this effect, we have analysed the expression of LFA-1; VLA-4, ICAM-1; CD44H and CD44v6 (haematopoietic and variant form respectively) on freshly isolated lymphocytes obtained from bone marrow (BM), peripheral blood (PB) and lymph node (LN) by flow cytometry. Overall, we find strong expression of CD44H, low to moderate expression of LFA-1, negative to low expression of VLA-4 and lack of expression of CD44v6. ICAM-1 expression was observed only in patients with prominent lymphadenopathy. Higher expression of CD44H in PB lymphoid cells relative to that of BM lymphoid cells correlated with higher PB lymphocytosis (p < 0.001). Proliferating cell nuclear antigen expression in LN sections correlated inversely with VLA-4 expression on BM and PB lymphoid cells (p < 0.05). There was no significant correlation between expression of CAMs and bcl-2 protein.

Auto-tumor reactive cytotoxic T-cell responses in B-cell non-Hodgkin's lymphoma.

We have generated cytotoxic T-lymphocytes (CTLs) from the peripheral blood (PB) of eight B-cell non-Hodgkin's lymphoma (NHL) patients by in vitro coculture with autologous fresh tumor cells. Their functional activity was assessed in 51Cr release assay and was found to be MHC class I restricted. Our results indicate the presence of T-cells cytotoxic for autologous tumor cells in the PB of these patients but these were relatively small numbers in small lymphocytic lymphomas (SLLs). Treatment of fresh tumor cells with rIFN-gamma and rTNF-alpha alone, or in combination significantly increased their susceptibility in 4/5 cases of SLLs, and a case of diffuse large cell lymphoma and Burkitt lymphoma (BL), while, B-cell lymphoma, rich in T-cells, did not show any appreciable increase. Fresh tumor cells were also analysed for MHC class I and ICAM-1 antigens by flow cytometry, in 5/8 cases before and after cytokine treatment. Significant upregulation of MHC class I antigens but with no detectable change in ICAM-1 observed in a case of SLL and BL, correlated with enhanced susceptibility. These findings suggest the possible role of MHC class I antigens in the cytotoxic susceptibility of autologous tumor cells in B-cell NHL.

Non-Hodgkin's lymphoma: cytotoxic T lymphocyte mediated activity correlated with histopathological classification and staging.

Non-Hodgkin's lymphomas (NHLs) constitute a heterogeneous group of lymphoid tumors and a majority of them in India are of B-cell phenotype. It has been postulated that immunoregulatory dysfunctions may be involved in the pathogenesis of NHL. Hence, peripheral blood mononuclear cells obtained from twenty six untreated patients were assessed for cytotoxic T lymphocyte mediated (CTL) activity in 51Cr release assay. Patients were classified according to Revised European American Lymphoma classification. B-cell small lymphocytic lymphoma patients showed lower CTL activity than NHL patients of other histopathological subtypes and healthy individuals. Diffuse large B cell lymphomas showed CTL activity comparable to healthy individuals. However, within the same histopathological subgroup, the CTL activity did not correlate with the stage of the patients.