Abstract

In order to carry out tissue typing studies in patients with rheumatoid arthritis (RA), 116 sera from pregnant multiparous women were screened for cytotoxicity specific for B lymphocytes. It was possible to identify three sera (M55, M58, M87) which reacted specifically with B cells after absorption with platelets. Each appeared to have a different specificity which was presumed to correspond to an alloantigen marker on the lymphocyte surface. The frequency of these alloantigen markers on B lymphocytes was investigated in patients with classical or definite RA and in controls. One of these, M58, occurred in 32 out of 43 RA patients (74 - 4%) compared with 10 out of 37 controls (27%). This difference was highly significant (P less than 0 - 0005). The relative risk of developing RA is 7 - 85 times greater in those possessing alloantigen M58. The other two B cell alloantigens failed to show any association with RA. The association with M58 may indicate a significant genetic contribution to disease susceptibility in RA.