Effect of recombinant human granulocyte-macrophage colony-stimulating factor (rhuGM-CSF) on normal peripheral B lymphocytes and B lymphoblastoid cell lines.

The role of the granulocyte-macrophage colony-stimulating factor (GM-CSF) for the proliferation and differentiation of normal and leukemic myeloid cells has been extensively investigated. We examined whether rhuGM-CSF has any functional effect on normal purified B cells and cell lines from patients with B cell non-Hodgkin's lymphomas (NHL). Normal B cells were prepared by combining E-rosetting followed by two non-adherence procedures. Further B cell enrichment was achieved by complement-mediated lysis with a panel of antibodies directed against various T cell antigens. Alternatively, we incubated the cells with monoclonal antibodies recognizing specific antigens on monocytes/macrophages and T cells followed by a separation with immunomagnetic beads coated with sheep anti-mouse IgG. With these different separation procedures B cell populations with a various content of monocytes/macrophages were obtained. An optimal enrichment of B cells up to 80-90% was achieved by combining E-rosetting, non-adherence, and separation with immunomagnetic beads. The proliferative response to rhuGM-CSF (0.01-1000 ng/ml) was assessed in a [3H]-thymidine uptake assay. RhuGM-CSF alone or in combination with anti-IgM or SAC did not cause any proliferative effect in normal B cells. Even in the presence of 35% monocytes (CD11+) as accessory cells no stimulatory effect could be measured. Similarly, the malignant B lymphoma cells did not show any proliferative response to rhuGM-CSF. To assess a potential differentiation-inducing capacity the Ig production was measured.(ABSTRACT TRUNCATED AT 250 WORDS)