Estrogen enhances immunoglobulin production by human PBMCs

It has been suggested that estrogen may enhance humoral immune responses and may be involved in the pathogenesis of autoimmune diseases.

We studied the in vitro effects of 17beta-estradiol (E2 ) on spontaneous immunoglobulin production by human PBMCs.

PBMCs from healthy human volunteers were cultured with E2. Levels of IgG and IgM and cytokine activity were measured by ELISA. Proliferation was determined by [3H]-thymidine uptake. The cell viability was assessed by a trypan blue exclusion test.

E2 enhanced IgG and IgM production of PBMCs both from men and women without altering cell viability and proliferation. The stimulatory effect of E2 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 E2 (10(-8) mol/L) was 220% of control cells, and that of IgM was 211%. Immunoglobulin production of E2 -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 E2 effect on immunoglobulin production of PBMCs; anti-IL-10 reduced IgG production in the presence of E2 from 206% to 154% of control cells, and that of IgM from 206% to 152%. E2 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 E2 -induced increase of immunoglobulin production by B cells, although this level of IL-10 alone was ineffective for B cells.

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 E2 may act as an important stimulator for human humoral immunity.