Specifically, self-reactive T cells cross-recognize microbial antigens and provide help to B cells bearing different specificities (bystander autoimmune B cells).817,819 For instance, influenza virus haemagglutinin-specific Tfh cells can help self-antigen MOG-specific B cells to produce autoantibodies when those B cells cocapture haemagglutinin and MOG.820 Collectively, Tfh cells potently drive the pathogenesis of autoimmune diseases through enhancing autoreactive B cell and CD8+ T cell responses. This evidence concerns the gene MOG and autoimmune disease.