A dual role of activin A in regulating immunoglobulin production of B cells.
Here, we report that activin A has a dual role in regulating Ig production of murine B cells. Activated B cells secrete activin activity by increasing activin A and decreasing follistatin expression. B cells also express type I and type II activin receptors, suggesting that they are targets of activin. Pretreatment of naïve B cells with activin A and subsequent activation by LPS resulted in increased cell growth and IgG production. In contrast, no significant effect was observed when activin A was added to naïve B cells simultaneously with LPS, indicating that activin A acts on resting but not activated B cells. In addition, activin A did not induce B cells to produce IgE, even when added prior to activation; however, in vivo antigen-specific IgE production was reduced significantly by neutralization of circulating activin A. These findings indicate that activin A plays an important role in Th2-mediated immune responses by enhancing antibody production through two distinct modes: acts directly on resting B cells to elicit full functions of activated B cells and acts indirectly on activated B cells through modulation of other immune cells.
Ogawa
Kenji
K
Laboratory of Cellular Biochemistry, RIKEN, Wako, Saitama, Japan. kkogawa@riken.jp
Funaba
Masayuki
M
Tsujimoto
Masafumi
M
D028341:Activins / Q000502:physiology*; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D005260:Female; D007073:Immunoglobulin E / Q000096:biosynthesis; D007074:Immunoglobulin G / Q000096:biosynthesis; D007136:Immunoglobulins / Q000096:biosynthesis*; D028322:Inhibin-beta Subunits; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D018418:Th2 Cells / Q000276:immunology; D053773:Transforming Growth Factor beta1 / Q000502:physiology
D007074:Immunoglobulin G; D007136:Immunoglobulins; D008070:Lipopolysaccharides; D053773:Transforming Growth Factor beta1; C422405:activin A; C103008:inhibin beta A subunit; D028341:Activins; D007073:Immunoglobulin E; D028322:Inhibin-beta Subunits