IgA-IgG cryoglobulinaemia with vasculitis.

Abstract

A mixed IgA/IgG cryoglobulin complex was found in the serum of a 61-year-old man suffering from rheumatoid arthritis, Raynaud's phenomenon and vascular purpura. The purified complex was progressively insoluble at temperatures below 37°C. Reversible loss of cryoprecipitability was seen in conditions of extreme pH, in concentrated urea solutions and in 2-mercaptoethanol. Inactivation of complement at 56°C did not affect cryoprecipitability. The complex contained no complement and showed no anticomplementary activity. Analytical ultracentrifugation of the cryoglobulin at 37°C showed 7S and 11S components present in equal concentration.