POU2AF1 arranges systemic distribution of follicular helper T cells (IRC10P.466)

Follicular helper T (Tfh) cells are a distinctive subset of CD4+ T helper cells, which play a critical role to establish specific humoral immunity by helping the germinal center formation of B cells. Currently, it is known that Tfh cells are maintained by BCL-6, MAF, and BATF; however, a mechanism managing Tfh cells is not fully clarified yet. To further dissect a regulator of Tfh cells, we employed transcriptome analysis of human tonsillar Tfh cells and thymic naive T cells as a control. Results demonstrated that, in addition to BCL-6, MAF, and BATF, Tfh cells highly expressed POU2AF1 (BOB.1 or OBF1) at transcript and protein levels. POU2AF1 is a transcriptional coactivator associated with either OCT1 or OCT2 through recognition of POU domains and assists B cells to produce specific antibodies. Analysis using Pou2af1-deficient mice showed that the expression levels of Pou2af1 did not seem to correlate the levels of Cxcr5,Icos,Tigit and Bcl-6 in Tfh cells. Mix cell culture experiments further revealed no functional differences in between Pou2af1-negative Tfh cells and control Tfh cells. But it was of our interest that, after stimulation with foreign antigens, the frequencies of Tfh cells in immune tissues and peripheral blood of Pou2af1-deficient mice were altered in comparison to those of wild-type mice. Taken together, these suggest that POU2AF1/Pou2af1 might have a role to regulate spreading manner of Tfh cells over the body from local sites of immune response.