As the presence of autoantibodies defines a distinct subset of patients [21], we also assessed the differences in receptor expression between seropositive and seronegative patients, which demonstrated increased levels of both CD200 and CD150 on TFH cells from seropositive patients with RA (P = 0.0045 and P = 0.0088 resp). The gene discussed is SLAMF1; the disease is rheumatoid arthritis.