Cytotoxic chemotherapy preceding apheresis of peripheral blood progenitor cells can affect the early reconstitution phase of naive T cells after autologous transplantation.

Transient T cell immunodeficiency is a common complication following hematopoietic stem cell transplantation. In breast cancer patients transplanted with autologous peripheral blood progenitor cells (PBPC) harvested after cytotoxic treatment with either cyclophosphamide or epirubicin plus paclitaxel, we evaluated T cells infused in grafts and in peripheral blood during the early reconstitution phase. We found that PBPC grafts harvested after treatment with epirubicin plus paclitaxel contained substantially larger numbers of T cells with less altered composition than after cyclophosphamide. Three months after high-dose cytotoxic chemotherapy, the numbers and the kinetics of circulating naive T cells, but not of memory and CD28- T cells, correlated positively with the number of naive T cells infused PBPC grafts. Finally, retrospective analysis of two cohorts of patients transplanted in different clinical settings with PBPC grafts harvested following cyclophosphamide or epirubicin plus paclitaxel showed apparently different susceptibilities to develop endogenous varicella zoster virus reactivation in the first year after high-dose cytotoxic chemotherapy. On the whole, these data indicate that number and composition of T cells in PBPC grafts vary according to the former cytotoxic therapy, and suggest that autologous transfer of T cells may accelerate the early T cell reconstitution phase and possibly ameliorate immune competence in patients rendered lymphopenic by high-dose chemotherapy.

Circulating CD33+ large mononuclear cells contain three distinct populations with phenotype of putative antigen-presenting cells including myeloid dendritic cells and CD14+ monocytes with their CD16+ subset.

BACKGROUND: In peripheral blood, myeloid markers identify a heterogeneous mixture of cells in transit from the bone marrow to peripheral tissues. Similarly, HLA-class II DR expression usually identifies mononuclear cells with the potential for developing antigen-presenting activity. We gathered putative antigen presenting cells bearing myeloid markers (My-APC) to study their composition by cell surface phenotype. METHODS: To gather and dissect My-APC phenotype while excluding lymphocytes and granulocytes, we developed a strategy based on staining red cell-lysed peripheral blood and gating cells bearing myeloid markers and physical parameters of large mononuclear cells. RESULTS: Phenotypic analysis within the My-APC gate showed three distinct populations. The largest fraction was constituted by CD14+ monocytes that extended into the other two populations, each expressing gradually lower levels of CD14 surface antigen along with increasing levels of CD16 and CD2, respectively. The CD16 and CD2 expression patterns extended from CD16+CD14+ or CD2+CD14+ double- positive intermediate cells toward each single positive subset, but they were reciprocally exclusive. Interestingly, CD2+CD14- cells within the My-APC gate were equivalent to myeloid dendritic cell precursors (pre-DC) defined previously by the absence of lineage markers and expression of HLA-DR and myeloid markers. Phenotypic analysis of each population revealed differences in the expression of costimulatory molecules and CD62L. CONCLUSIONS: This novel analytical approach allowed us to distinguish circulating My-APC in three subsets and to identify relationships between monocytes and other related myeloid populations including DC.

Minimal tumor contamination of hematopoietic harvests from breast cancer patients can be easily detected by liquid culture assay.

BACKGROUND: Recurrence after PBSC transplantation in breast cancer (BC) patients may be related to the reinfusion of tumor cells contaminating the graft. We have developed a liquid culture (LC) method for the identification of viable epithelial tumor cells in PBSC collections. METHODS: Mononuclear fraction from PBSC harvests of BC patients undergoing high dose chemotherapy (HDC) (adjuvant setting n = 60, metastatic disease n = 30) were seeded in petri dishes containing round cover slips. Cells were cultured for 3 weeks, then cover slips were stained with the pan-cytokeratin A45-B/B3 mAb and scored under a light microscope. Samples were considered positive when more than one adherent cell or a cluster of cells staining bright red was present. Results were compared with those obtained on cytospins prepared directly from the PBSC harvest. Specificity of the method was tested on lymphoma patients, collections: all were negative. The sensitivity, evaluated by serial dilutions of CG5 BC cell line, was 1 epithelial cell in 10(6) mononuclear cells. RESULTS: The percentage of positivity was superimposable in the two groups (adjuvant 25%, metastatic 24%). However, a significantly higher proportion of positive samples from metastatic vs adjuvant patients has shown the presence of tumor clusters (86% vs 33%, p = 0.063). In 21% of all samples a discrepancy with the results obtained by immunocytochemical analysis (ICC) was found, mostly due to liquid-culture-positive/ICC-negative PBSCs. DISCUSSION: Our data suggest that LC assay may enhance the identification of viable disseminated epithelial tumor cells in PBSC grafts and might provide insights about their growth capacity.

Efficacy of epirubicin/paclitaxel combination in mobilizing large amounts of hematopoietic progenitor cells in patients with metastatic breast cancer showing optimal response to the same chemotherapy regimen.

BACKGROUND AND OBJECTIVE: Based on our preliminary experience, we have further evaluated the capacity of the paclitaxel/epirubicin combination (at the dose of 175 and 90 mg/m(2), respectively) plus G-CSF to mobilize hematopoietic progenitors into the circulation. DESIGN AND METHODS: The study was conducted in a homogeneous cohort of 25 stage IV breast cancer patients showing response to three cycles of the same chemotherapy regimen and who were included in a high-dose chemotherapy program. RESULTS: In most cases (68%) more than 5_10(6) CD34+ cells/kg b.w. (the threshold fixed in our study) were collected by a single leukapheresis, 28% and 4% of patients requiring 2 and 3 procedures, respectively. Based on the CD34+ cell count in the peripheral blood, most of the leukaphereses (53%) were performed on day 11 after chemotherapy. More than 50 CD34+ cells/mL along with a preleukapheresis WBC count between 10 and 20_10(9)/L predicted that only a single harvest would be required in 100% of cases. The evaluation of the clonogenic potential of collected cells showed that a large number of committed colony-forming cells (CFCs) and more primitive long-term culture-initiating cell (LTC-IC) hematopoietic progenitors were present in 20 harvests studied. INTERPRETATION AND CONCLUSIONS: These data demonstrate that the epirubicin/paclitaxel combination followed by G-CSF, besides being a very active regimen in MBC, is effective in releasing large amounts of progenitor cells into the circulation which can then be safely employed to support myeloablative regimens.

Somatic mutations at the T-cell antigen receptor in antineoplastic drug-exposed populations: comparison with sister chromatid exchange frequency.

OBJECTIVE: The objective of this study was to assess the genetic effect of occupational exposure to antineoplastic agents. METHOD: The influence of occupational handling of cytotoxic drugs was investigated by monitoring the frequency of sister chromatid exchanges (SCE), the percentage of cells with high frequencies of SCE (high-frequency cells, HFC), and the frequency of somatic mutation at the T-cell receptor (TCR) locus in mononuclear cells of exposed hospital nurses. These parameters were also measured in healthy donors and in cancer patients at the time of the diagnosis and following the administration of high doses of cytotoxic drugs requiring stem cell support. RESULTS: Our results show that (a) SCE and HFC values in occupationally exposed nurses do not differ from controls, (b) patients with newly diagnosed cancer or following chemotherapy show a number of SCE comparable to those of healthy donors, but a significantly different percentage of HFC, (c) cigarette smokers of all categories studied show higher frequencies of SCE and HFC as compared to nonsmokers, but the differences are not statistically significant, (d) the mutation frequency at the TCR locus in oncology nurses is higher, but not significantly different from the frequency in the control group, and (e) the increase of mutation frequency is statistically significant and seems to be dose dependent in patients treated with high-dose chemotherapy. CONCLUSIONS: Our data suggest that SCE frequency and HFC percentage are not reliable indicators of exposure to possible mutagenic/carcinogenic effects of antineoplastic drugs; on the contrary, our observations indicate that anticancer therapy induces somatic mutations at the TCR locus and suggest an association between exposure to cytotoxic agents and the increase in somatic mutations.

Autologous platelet transfusion in patients receiving high-dose chemotherapy and circulating progenitor cell transplantation for stage II/III breast cancer.

BACKGROUND AND OBJECTIVE: Concerns about the risk of transfusion therapy are driving towards new strategies which are designed to minimize exposure to allogeneic blood products. We aimed to find out whether it is possible to support the phase of thrombocytopenia following high-dose chemotherapy (HDC) and circulating progenitor cells (CPC) transplantation by autologous platelet concentrates (PC). DESIGN AND METHODS: PC were collected from 32 patients undergoing HDC and CPC transplantation for stage II/III breast cancer. A single plateletpheresis was performed at rebound after high-dose cyclophosphamide, when platelet count exceeded 250 x 10(9)/L. PC were cryopreserved in 5% DMSO after controlled-rate freezing and stored in liquid nitrogen. In vitro studies of cryopreserved platelets (aggregation, ATP release and change of mean platelet volume induced by EDTA) were performed. When platelet counts dropped below 20 x 10(9)/L following HDC (thiotepa 600 mg/m2, L-PAM 160 mg/m2) and CPC transplant (CD34+ cells > 5 x 10(6)/kg), PC were thawed in a 37 degrees C water bath, centrifuged to remove DMSO, resuspended in autologous plasma and reinfused within one hour. RESULTS: Large quantities of platelets were harvested in all patients (median 6.6 x 10(11), range 4.8-12.2). In vitro studies showed preserved platelet function as compared to both fresh platelets and standard PC. Twenty-eight out of 32 patients received autologous PC. At the time of transfusion most of the patients were febrile (> 38 degrees C) and had mucositis > G2. The median number of platelets reinfused was 3.8 x 10(11) (range 2.0-8.1) with a median loss during the freeze-thaw-wash procedure of 37%. Autotransfusion was able to maintain platelet count above 20 x 10(9)/L in most patients, with a corrected count increment > 7.5 in 20 cases. Four patients required one additional allogeneic transfusion, two because of a poor increment and two due to a late-occurring epistaxis. No side effects related to PC infusion were recorded. Sixteen control patients who received the same HDC and a similar number of CD34+ cells required a total of 17 allogeneic PC units (1 patient did not require platelet transfusion). INTERPRETATION AND CONCLUSIONS: Our data demonstrate that large doses of autologous platelets can easily be collected and safely administered to support the period of thrombocytopenia in patients undergoing HDC and CPC transplantation. Autologous PC in these patients can abrogate the risks deriving from allogeneic platelet transfusion.

Hematopoietic progenitor cell collection and neoplastic cell contamination in breast cancer patients receiving chemotherapy plus granulocyte-colony stimulating factor (G-CSF) or G-CSF alone for mobilization.

BACKGROUND: We compared hematopoietic progenitor cell (HPC) collection and neoplastic cell contamination in breast cancer patients given cyclophosphamide (CTX) plus granulocyte-colony stimulating factor (G-CSF) or G-CSF alone for mobilization. PATIENTS AND METHODS: In 57 stage II-III breast cancer patients, CD34+ cells, colony-forming units-granulocyte macrophage (CFU-GM), early HPC and breast cancer cells were counted in HPC collections obtained after CTX plus G-CSF (n = 27) or G-CSF-alone mobilization (n = 30). RESULTS: The CD34+ cell collection was about two-fold greater after CTX plus G-CSF mobilization (11.0 +/- 7.9 vs. 5.8 +/- 3.5 x 10(6)/kg, P < 0.001). Similarly, the total number of CFU-GM, CD34+CD38- cells and of week-5 cobblestone area forming cells (CAFC) collected was significantly higher in patients mobilized with CTX plus G-CSF. Breast cancer cells were found in the apheresis products of 22% of patients mobilized with CTX plus G-CSF and in 10% of patients mobilized with G-CSF alone (P = 0.36). Of seven patients who failed G-CSF-alone mobilization and eventually underwent chemotherapy plus G-CSF mobilization, none had cytokeratin-positive cells after G-CSF mobilization, whereas four out of seven had cytokeratin-positive cells after chemotherapy plus G-CSF (P = 0.07 by chi 2 test). CONCLUSION: The CTX plus G-CSF mobilization protocol was associated with a significantly higher HPC collection. However, this benefit was not accompanied by a reduction in the incidence of tumor-contaminated HPC graft.

A new method for placental/cord blood processing in the collection bag. I. Analysis of factors involved in red blood cell removal.

We describe a new procedure for large-scale CB processing in the collection bag, thus minimizing the risk of CB contamination. A solution of 6% hydroxyethyl starch (HES) was added directly to the CB containing bag. After RBC sedimentation at 4 degrees C, the WBC-rich supernatant was collected in a satellite bag and centrifuged. After supernatant removal, the cell pellet was resuspended and the percent recovery of total WBC, CD34+ progenitor cells, CFU-GM and cobblestone area-forming cells (CAFC) evaluated. Results obtained with three different types of CB collection bags (300, 600 and 1000 ml) were analyzed and compared with those of an open system in 50 ml tubes. CB processing procedures in 300 and 1000 ml bags were associated with better WBC, CFU, CD34+ cell and CAFC recovery (83-93%). This novel CB processing procedure appears to be easy, effective and particularly suitable for large-scale banking under GMP conditions.

CG5/Dx human breast cancer cell line: characterization of a new doxorubicin-resistant variant.

By continuous exposure of CG5 human breast cancer cell line to increasing doxorubicin (Dx) concentrations, a multidrug-resistant (MDR) subline (CG5/Dx) was obtained. The resistant variant showed P-glycoprotein (P-gp) expression and a lower intracellular doxorubicin level than the parental cells. CG5/Dx cells were 19.4 fold more resistant to Dx than CG5 cells and showed a cross-resistance to some structurally related and unrelated compounds. Differences in kinetics, biological and ultrastructural features between the two cell lines were investigated. The CG5/Dx cells grew more slowly, produced higher CEA levels and showed a reduced progesterone receptor (PgR) content than the parental cells. Ultrastructural studies revealed differences involving, polyribosomes, rough endoplasmic reticulum, [mitochondria] and cytoskeleton.

Engineered stromal layers and continuous flow culture enhance multidrug resistance gene transfer in hematopoietic progenitors.

We recently reported that in stroma-free cultures 11-33% of clonogenic cells derived from a bulk long-term culture [long-term culture-clonogenic cells (LTC-CC)] could be transduced by supernatant exposure or coculture of human CD34+ progenitors with MDR retroviral producer line A12M1. We reasoned that a stromal cell layer may generate niches in which LTC-CC could enter in the S-phase, thus becoming a more accessible target for gene delivery. In static culture studies in flasks, human engineered stromal cell line L87/4 or stromal murine M2-10B4 cells were used as feeder after irradiation, and CD34+ cells from either cord blood or peripheral blood of mobilized cancer patients were exposed to MDR supernatant for 7 consecutive days before 5-week culture for LTC-CC evaluation. In continuous flow perfusion culture studies, CD34+ cells were seeded over irradiated stromal murine M2-1OB4 cells and exposed to MDR supernatant for 7 days before LTC-CC evaluation. In mock-transduced controls, <5% of LTC-CC were found to he viable after exposure to 10 ng/ml Taxol. In cells exposed to MDR supernatant in static stroma cultures, 68 +/- 4% of seeded LTC-CC were found to be drug resistant and express MDR mRNA as evaluated by reverse transcription-PCR analysis of single colonies. The addition of cytokines did not further enhance transfer efficiency. After MDR retroviral exposure in continuous flow cultures, 88 +/- 5% of LTC-CC were found to be drug resistant (P < 0.01 versus static stroma culture). P-glycoprotein expression in CD34+ cells was evaluated using flow cytometry and found to he higher after continuous flow versus static cultures. Finally, very high levels of P-glycoprotein expression after MDR supernatant exposure in the presence of stroma were confirmed by APAAP staining of cultured cells. We conclude that engineered stromal cell layers and continuous flow culture conditions can significantly enhance retroviral-mediated gene transfer into human hematopoietic progenitor cells.

Medroxyprogesterone-acetate reverses the MDR phenotype of the CG5-doxorubicin resistant human breast cancer cell line.

In malignant cells multidrug resistance (MDR) is frequently associated with the expression of a 170 KDa P-glycoprotein (P-gp) in the plasma membrane. P-gp acts as an ATP-dependent efflux pump causing a decreased intracellular accumulation of structurally unrelated natural anticancer agents such as anthracyclines. Doxorubicin (DX) resistance is mostly related to the multidrug resistance gene product P-gp. In our experiments the revertant activity of medroxyprogesterone acetate (MPA) in comparison to that of the well known revertant agent verapamil (VRP) was investigated. In vitro tests were carried out on a DX-resistant variant (CG5/DX) obtained in our laboratory from the parental CG5 human breast cancer cell line by continuous exposure to the drug. The ability of MPA to modulate intracellular DX accumulation and to reverse MDR was evaluated. MPA appeared more active than VRP in reversing MDR, suggesting a possible role of this synthetic progestin as chemosensitizing agent in the clinical management of anthracycline-resistant breast cancer.

Stem cell factor and interleukin-6, alone or in combination with granulocyte colony-stimulating factor, do not affect the growth of solid tumor cell lines.

Hematopoietic growth factors (HGFs) are glycoproteins that control hemopoiesis. They have potential usefulness in a range of clinical conditions including the treatment of patients with myelosuppression induced by chemotherapy. Among HGFs, Stem Cell Factor (SCF) and Interleukin 6 (IL-6) are attracting interest for their capacity to stimulate early hematopoietic progenitors. Furthermore, their use in combination with late-acting growth factors with a more lineage-restricted potential (such as granulocyte colony-stimulating factor, G-CSF) might be expected to offer optimal marrow stimulation and usefulness in clinical oncology. Since non-hematopoietic malignant cells may express receptors for HGFs and respond to these peptides in vitro, we investigated clonal growth 3H-thymidine incorporation and cell cycle analysis by flow cytometry of 5 human solid tumor cell lines under the influence of SCF and IL-6 with or without G-CSF. Our experiments show that these cytokines have no effects on the proliferative capacity of the cell lines tested. Based on our and previously reported data, the use of these HGFs can be considered safe in cancer patients.

Morphological and biochemical features of a medroxyprogesterone acetate (MPA)-resistant MCF-7 breast cancer cell line.

An MCF-7 human breast cancer line variant (MCF-7/MPA), resistant to medroxyprogesterone-acetate (MPA), was obtained by continuous exposure in vitro to the drug. MCF-7/MPA cells were grown in the presence of 12.5 x 10(-6) M MPA and were selected by increasing the concentration of the drug in the growth medium in a stepwise manner from 0.025 x 10(-6) M up to 12.5 x 10(-6) M. Comparative studies of cellular morphology, cytosolic steroid receptor content and P-Glycoprotein expression were performed on both MCF-7 parental line and MCF-7/MPA variant. MCF-7/MPA cells, when compared to the parental line, exhibit a different morphology in terms of membrane alterations, reduced content of cytosolic progesterone receptor, increased expression of P-glycoprotein along with reduction of Doxorubicin (Dx) activity on the growth of MCF-7/MPA resistant cells.

Multiparametric assessment of the cell-cycle effects of tamoxifen on mcf-7 human breast-cancer cells.

Tamoxifen (TAM)-induced changes in proliferation kinetics of the human breast cancer cell line MCF-7 were investigated using dual parameter flow cytometry (FCM) of bromodeoxyuridine (BrdU) immunolabelling and of the expression of cell-cycle related proteins (the proliferating cell nuclear antigen, PCNA, and the non proliferation-specific protein, Statin), versus the DNA content. Single-parameter FCM DNA histograms confirmed that after 96 hours of treatment with 10(-7) M TAM the fraction of S-phase cells decreased significantly, with a simultaneous accumulation of cells in the G(0)/G(1) range of DNA content. In dual-parameter FCM cytograms, the fraction of BrdU-positive cells after TAM exposure was significantly lower than in the controls, and no unlabeled S-phase cells were found. The TAM-induced block in G(0)/G(1) phase was paralleled by a decrease in the number of cells with a DNA content typical of the S-phase expressing PCNA, and by an increase in Statin-positive (G(0)) cells. Upon readdition of 10(-9) M 17 beta-estradiol (E2) to the TAM-treated cultures, BrdU-labelling as well as PCNA expression levels increased significantly, whereas the fraction of Statin-positive cells remained higher than in the controls. The results obtained confirm that the TAM-induced inhibition of cell growth is associated with major changes in the cell cycle parameters of MCF-7 cells, and provide experimental evidence that two main mechanisms are operating: the accumulation of cells in G(1), before the onset of S-phase, and the exit of some cells from the cycling compartment; however, some of those that are blocked at G(0); cannot be totally reversed by estrogens and may be permanent; These data should be taken into account in the attempt to combine the antiestrogen treatment with chemotherapy more effectively.

Cell cycle kinetic effects of tamoxifen on human breast cancer cells. Flow cytometric analyses of DNA content, BrdU labeling, Ki-67, PCNA, and statin expression.

Tamoxifen is known to inhibit the growth of some human mammary carcinoma cells; this effect is accompanied by a decrease in the proportion of cells synthesizing DNA. In this work, flow cytometry of DNA and of bromodeoxyuridine labeling and the evaluation of the cell cycle-related antigens Ki-67, PCNA, and statin were used to investigate the changes in the proliferation kinetics of MCF-7 cells before and after treatment with 10(-7) M TAM. The treatment with TAM induced a significant decrease in the fraction of S-phase cells and an increase in those with a DNA content typical of G0/1 phase. The TAM-induced block in G0/1 is paralleled by a decrease in the frequency of cells expressing Ki-67 and PCNA, and by an increase in statin-positive (G0) cells. These results confirmed that the TAM-induced inhibition of cell growth is associated with major changes in the cell cycle parameters of MCF-7 cells, and provide the first experimental evidence that two main mechanisms are operating: the accumulation of cells in G1, before the onset of S-phase, and the exit of some cells from the cycling compartment.

Effect of recombinant human erythropoietin on hematopoietic and non-hematopoietic malignant cell growth in vitro.

BACKGROUND: Several clinical studies have shown that recombinant human erythropoietin (rHuEpo) can ameliorate the anemia associated with hematologic malignancies and solid tumors. On the other hand, only a few studies have been performed to investigate whether rHuEpo can affect or modulate the growth of malignant cells. MATERIALS AND METHODS: We studied the effects of rHuEpo (0.5 to 10 IU/mL) on clonogenic growth and cell kinetics in ten cell lines derived from both hematologic malignancies and solid tumors. Clonogenic assays were performed by plating 5 x 10(3) cells in agar, while the percentage of cells in S phase was assessed by DNA flow cytometry. RESULTS: rHuEpo did not affect either in vitro colony formation or S phase percentage in the human erythroid cell lines K-562 and HEL expressing erythropoietin receptors (< 40 receptors per cell). No effect of rHuEpo was observed in the remaining hematopoietic cell lines or in five solid tumor cell lines. CONCLUSIONS: These findings indicate that rHuEpo, even at very high concentrations, does not affect either clonogenic growth or DNA synthesis in the cell lines tested. Available evidence suggests that rHuEpo can be safely employed in all malignancies except acute myeloid leukemia.

Proliferative effect of dexamethasone on a human glioblastoma cell line (HU 197) is mediated by glucocorticoid receptors.

The relationship between Dexamethasone proliferative activity and the presence of glucocorticoid receptors was studied on a human glioblastoma cell line (HU 197). For this purpose, the 17 beta-Carboxamide steroid DXB, a glucocorticoid antagonist that competes with Dexamethasone for binding to the intracellular glucocorticoid receptor but does not trigger the glucocorticoid effect, was used. Concurrent treatments with Dexamethasone and DXB caused an inhibition of the proliferative effect obtained by Dexamethasone. The results obtained demonstrated that the Dexamethasone activity on cell proliferation is a specific receptor-mediated effect.

Establishment and characterization of two cell lines derived from human glioblastoma multiforme.

We established and characterized two cell lines derived from glioblastoma multiforme. Both cell lines exhibited tumor cell morphology and growth kinetics and showed variable expression of glial fibrillary acidic protein (GFAP), S-100, fibronectin and vimentin. Cytofluorimetrical analysis of tumor samples showed a diploid DNA distribution, whereas permanent culture cells evolved to the hyperdiploid DNA content. Karyotype studies revealed cytogenetical abnormalities described in glial tumors including gain of chromosome 7, loss of chromosome 10 and presence of double minutes (DMs). Enhanced expression of Ha-ras and c-myc genes resulted from high p-21 and p-62 levels. The contemporary presence of TGF-alpha and EGF-Rc transcripts suggested an autocrine mechanism in the cell lines growth.

A study on the biological behavior of human brain tumors. Part II: Steroid receptors and arachidonic acid metabolism.

The significance of steroid receptors (SR) in human brain tumors is presently a field of intense investigation in order to clarify some aspects of the biological behavior of these neoplasms. We studied the relationship between the presence of steroid receptors and the production of metabolites of the arachidonic acid cascade which have been reported to have a role in the biological behavior of some human tumors. We found that some metabolites of arachidonic acid are produced in different amounts in brain tumors which either did or did not express some steroid receptors. In particular the PGE2 were higher in estrogen receptors (ER) positive meningiomas than in ER negative ones and 6-keto-PGF1 alpha, the stable metabolite of prostacyclin, is significantly higher in androgen receptors (AR) negative meningiomas than in AR positive ones. In neuroepithelial tumors the glucocorticoid receptors (GR) positive cases synthesized more TxB2 and less PGE2 than the GR negative ones. Our data seem to suggest that some correlations exist between the presence of some steroid receptors and arachidonic acid metabolite production.