Rubella-associated arthritis. II. Relationship between circulating immune complex levels and joint manifestations.

The role played by raised circulating immune complex (CIC) levels in the pathogenesis of rubella-associated joint reactions has been assessed during the course of RA 27/3 rubella immunisation and epidemic wild rubella infection. CIC levels were evaluated by C1q microplate enzyme-linked immunosorbent assay (ELISA) and Raji cell ELISA techniques. Mean CIC levels were generally higher both before and after immunisation among individuals developing vaccine-associated arthritis than among those developing arthralgia or no joint symptoms. However, these differences reached statistical significance only with CIC (Raji) techniques at six and 12 weeks postimmunisation. The proportion of individuals within each group having raised CIC levels (greater than or equal to 2SD above normal control values) was also higher in the postvaccine arthritis group, though statistically significant differences were not found with either Raji or C1q techniques. These data do not support a direct role for raised CIC levels in the pathogenesis of rubella-associated arthritis or arthralgia.