[T and B cell immune reactions in inflamed tissue]

The T and B lymphocytes in secondary lymphoid organs, such as the spleen and lymph nodes, normally reliably protect our body from infectious diseases; however, in rheumatoid arthritis they infiltrate tissues and substantially contribute to tissue destruction in rheumatic joints by production of inflammatory chemokines and autoreactive antibodies. It was previously unclear whether these lymphocytes infiltrate tissues as fully differentiated effector cells from neighboring lymph nodes or whether they are locally generated. A recent study has now shown that T and B cells actively cooperate together even outside lymphoid tissue. A follicular T‑helper cell-like population promotes the local generation of germinal center-like B cells and high-affinity plasma cells.