KLRB1 and rheumatoid arthritis: Non-classical CD161+CCR6+ Th1 lymphocytes of rheumatoid arthritis patients, unlike classical CD161-CCR6- Th1 cells, are reprogrammed into pathogenic Th17 lymphocytes in Th17-inducing conditions (127), which may contribute to their pathogenicity during the course of rheumatoid arthritis.