Modalities of in vitro IgM and IgG production by peripheral blood lymphocytes of chronic lymphocytic leukemia patients and healthy volunteers.

In vitro spontaneous and mitogen (LPS, rIFN alpha and PWM) or cytokine (rIL-2) induced IgM and IgG production by peripheral blood lymphocytes of 15 CLL patients and 16 healthy volunteers has been determined. This study has shown: (1) that there is no difference between healthy donors and CLL patients in respect to level and variability of spontaneous immunoglobulin production by their lymphocyte cultures; (2) that there is no correlation between the percentage of B cells in individual cell cultures obtained from CLL patients and the amount of spontaneously produced IgM or IgG; (3) that there is a correlation between spontaneous in vitro IgM production and IgM content in the serum of the patient; (4) that in CLL patients selective augmentation of IgM production could be obtained after stimulation with PWM or rIL-2, but only in those cultures which spontaneously produce more than 35 ng/ml of IgM and (5) that the number of lymphocyte cultures able to be stimulated to IgM production is about 10 times smaller when they originate from CLL patients than from healthy volunteers. These findings are in line with the view that B cells in CLL patients often do not differentiate due to the insufficiency of factor(s) secreted by their own activated T-cells, but that in essence they follow the same differentiation pathway as normal B-cells.