Decreased immunoglobulin production by a human lymphoid cell line following melphalan treatment

The effect of melphalan on immunoglobulin G (IgG) production by a human lymphoblastoid cell line (BF) was studied. The amount of secreted IgG and the percentage of cells containing cytoplasmic IgG were measured by immunoassay and cytofluorometry, respectively. Dose-response studied indicated that melphalan concentrations of 2 X 10(-8) M had no effect, while concentrations of 8 X 10(-7) M were totally toxic, after 72-hr exposures to the drug. Statistically significant, persistent, alterations in both synthesis and secretion of IgG by BF cells were observed following treatment for 72 hr with 4 X 10(-7) M melphalan, and there was an increase in population-doubling time from 24 to 72 hr in these drug-treated cells. The percentage of IgG-containing cells in melphalan-treated cultures was significantly decreased as compared to control cultures. IgG secretion was also decreased in these cultures, and the variation in IgG secretion as a function of cellular growth was significantly altered following melphalan treatment. Decreased IgG production following melphalan treatment may be related to altered cell cycle kinetics. Based on immunological analysis, there was no evident alteration in the IgG secreted by melphalan-treated cells, nor did melphalan treatment produce a cellular population lacking IgG entirely.