B Cell-Extrinsic Myd88 and Fcer1g Negatively Regulate Autoreactive and Normal B Cell Immune Responses.

ABSTRACT: MyD88 and FcR common ?-chain (Fcer1g, FcR?) elicit proinflammatory responses to exogenous Ags. Deletion of these receptors in autoimmune models has generally led to reduced overall disease. In B cells, Myd88 is required for anti-DNA and anti-RNA autoantibody responses, whereas Fcer1g is not expressed in these cells. The roles of these receptors in myeloid cells during B cell autoimmune activation remain less clear. To investigate the roles of Myd88 and Fcer1g in non-B cells, we transferred anti-self-IgG (rheumatoid factor) B cells and their physiologic target Ag, anti-chromatin Ab, into mice lacking Fcer1g, Myd88, or both and studied the extrafollicular plasmablast response. Surprisingly, we found a markedly higher and more prolonged response in the absence of either molecule; this effect was accentuated in doubly deficient recipients, with a 40-fold increase compared with wild-type recipients at day 10. This enhancement was dependent on CD40L, indicating that Myd88 and FcR?, presumably on myeloid APCs, were required to downregulate T cell help for the extrafollicular response. To extend the generality, we then investigated a classic T cell-dependent response to (4-hydroxy-3-nitrophenyl)acetyl conjugated to chicken ? globulin and found a similar effect. Thus, these results reveal novel regulatory roles in the B cell response for receptors that are typically proinflammatory.

SUBMITTER: Sweet RA 

PROVIDER: S-EPMC5547912 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature