Segmented filamentous bacteria (SFB) drives enhanced T cell-dependent IgA and IgG2b responses in Peyer’s patches

Abstract Peyer’s patches (PPs) are the major site for T-cell dependent IgA B-cell differentiation. Segmented filamentous bacteria (SFB) commensal that preferentially colonize ileum, mainly over PPs. SFB colonization of germ-free mice induces polyclonal responses by unclear mechanisms. Using scmRNAseq and flow cytometry we found SPF induced an increase in size overall cell number PPs includes enhanced numbers naïve, follicular, germinal center B-cells as well Th 17 Tfh cells. increased +and IgG2b +, but not IgG1 +B-cells Enhanced class-switching to was on T-cells, CCR6, CD40-CD40L DC-expression MHCII, some degree IL-6. An activated CD11c +SIRPa +BST2 −CD11b +DCs with CCR6 +Th17 +compared −mice suggests initiation class switching PP subepithelial dome (SED). conversion Th17 into cells, however unlike previous reports, SFB-colonized IL-17R −/−and CD4 CRE-RORg tfl/flmice indicated neither IL-17, nor from cells is required responses. Finally, B repertoire analysis +PP showed affected qualitatively quantitatively. Together, these data indicate enhances recruitment naïve drives antibody through T cell-dependent PPs, contribute our understanding how microbes affect humoral immune infection vaccination. This work supported Division Intramural Research, NIAID, NIH