AUTHOR=Marks Ellen, Ortiz Carla, Pantazi Eirini, Bailey Charlotte S., Lord Graham M., Waldschmidt Thomas J., Noelle Randolph J., Elgueta Raul TITLE=Retinoic Acid Signaling in B Cells Is Required for the Generation of an Effective T-Independent Immune Response JOURNAL=Frontiers in Immunology VOLUME=7 YEAR=2016 URL=https://www.frontiersin.org/articles/10.3389/fimmu.2016.00643 DOI=10.3389/fimmu.2016.00643 ISSN=1664-3224 ABSTRACT=Retinoic acid (RA) plays an important role in the balance of inflammation and tolerance in T cells. Furthermore, it has been demonstrated that RA facilitates IgA isotype switching in B cells in vivo. However, it is unclear whether RA has a direct effect on T-independent B cell responses in vivo. To address this question, we generated a mouse model where RA signaling is specifically silenced in the B cell lineage. This was achieved through the overexpression of a dominant negative receptor α for RA (dnRARα) in the B cell lineage. In this model, we found a dramatic reduction in marginal zone (MZ) B cells and accumulation of transitional 2 B cells in the spleen. We also observed a reduction in B1 B cells in the peritoneum with a defect in the T-independent B cell response against 2,4,6-trinitrophenyl. This was not a result of inhibited development of B cells in the bone marrow, but likely the result of both defective expression of S1P1 in MZ B cells and a defect in the development of MZ and B1 B cells. This suggests that RARα expression in B cells is important for B cell frequency in the MZ and peritoneum, which is crucial for the generation of T-independent humoral responses.