Pathologically expanded peripheral T helper cell subset drives B cells in rheumatoid arthritis

The authors identify in patients with rheumatoid arthritis a pathogenic subset of CD4+ T cells that augments B cell responses within inflamed tissues. Michael Brenner and colleagues identify a subset of pathogenically activated PD-1hi CD4-positive T cells in patients with rheumatoid arthritis, and show that it promotes B-cell responses in tertiary lymphoid structures. The cells, which the authors designate as 'peripheral helper' T cells, differ...