We have recently shown that activin A, a member of TGF-$eta$ superfamily, stimulates mouse B cells to express IgA isotype but other isotypes. In the present study, we further characterized effects of activin A on B cell growth and IgA expression. We found that activin A did not have effect on LPS-stimulated cell viability. In parallel, CFSE staining analysis revealed that activin A did not alter cell division. An increase of IgA secretion by activin A was completely abrogated by anti-activin A Ab but not by anti-TGF$eta$1 Ab. In the same conditions, no other isotypes are significantly affected by each antibody treatment. Finally, activin A, as similar to TGF-$eta$1, increased IgA secretion by mesenteric lymph node cells. These results suggest that activin A can specifically stimulate IgA response, independent of TGF-$eta$ in the gut.