17β-Estradiol Expands IgA-Producing B Cells in Mice Deficient for the μ Chain.

Oestrogen is not only a sex hormone but also an important regulator of the immune system. Expression of the heavy chain of IgM (μ) is essential for B-cell differentiation. However, a small number of IgA-positive B cells can be found in mice lacking the μ chain (μMT−/−). The aim of this study was to investigate the effects of oestrogen on this alternative B-cell pathway in μMT−/− mice. Our results clearly demonstrate that oestrogen increases the frequency of IgA-producing B cells in μMT−/− mice in both bone marrow and spleen cells. We also show that mature IgM-producing B cells are not required for oestrogen-mediated suppression of granulocyte-mediated inflammation or thymic involution. In conclusion, we demonstrate that 17β-estradiol benzoate increases the frequency of IgA-producing B cells in μMT−/− mice, suggesting that oestrogen can influence the alternative B-cell pathway found in μMT−/− mice. [ABSTRACT FROM AUTHOR]