TIGIT and rheumatoid arthritis: A pathogenic role for TIGIT has been implicated by two other groups, one of which demonstrated that a pathogenic subset of Tfh cells circulating in human RA patients' blood can be identified in part by enhanced expression of TIGIT (59), and the other of which demonstrated increased B cell costimulatory activity in a TIGIT+ subset of Tfh cells, which is inhibited by anti-TIGIT blocking antibodies (58).