Estrogen enhances immunoglobulin production by human PBMCs

Background: It has been suggested that estrogen may enhance humoral immune responses and may be involved in the pathogenesis of autoimmune diseases, Objective: We studied the in vitro effects of 17 beta-estradiol (E-2) on spontaneous immunoglobulin production by human PBMCs. Methods: PBMCs from healthy human volunteers were cultured with E-2. Levels of IgG and IgM and cytokine activity were measured by ELISA, proliferation was determined by [H-3]-thymidine uptake. The cell viability was assessed by a trypan blue exclusion test. Results: E-2 enhanced IgG and IgM production of PBMCs both from men and women without altering cell viability and proliferation, The stimulatory effect of E-2 was revealed at 10(-10) mol/L, increased in a dose-dependent fashion, and was maximized at 10(-8) mol/L, IgG production of PBMCs in the presence of E-2 (10(-8) mol/L) was 220% of control cells, and that of IgM was 211%. Immunoglobutin production of E-2-treated B cells was slightly higher than that of control cells; IgG production was 161% of control cells, and that of IgM was 157%. Anti-IL-10 antibody partially blocked the E-2 effect on immunoglobulin production of PBMCs; anti-IL-10 reduced IgG production in the presence of E-2 from 206% to 151% of control cells, and that of IgM from 206% to 152%. E-2 increased IL-10 production of monocytes up to 250% of control level, but it did not affect that of T cells or B cells. Exogenous IL-10 (1 U/mL) further enhanced E-2-induced increase of immunoglobulin production by B cells, although this level of IL-10 alone was ineffective for B cells. Conclusion: These results suggest that E2 may increase immunoglobulin production of human PBMCs mainly by increasing IL-10 production of monocytes, The results also support that E-2 may act as an important stimulator for human humoral immunity.