Detection of Schistosoma mansoni M antigen in circulating immune-complexes and in kidneys of infected hamsters.

Circulating M antigen (CMA) of Schistosoma mansoni was found in the trichloroacetic acid (TCA) soluble fraction of a polyethylene glycol precipitate of serum from infected hamsters. It was also found as a TCA-soluble component in an immunoglobulin-containing fraction eluted from infected hamster kidneys. It was not found in similarly treated control sera nor in the products of acid dissociation of circulating immune complexes (CIC) from infected hamster sera. CMA was not detected in the kidneys of normal hamsters. Precipitating anti-M antigen antibodies were present in one of 10 sera from infected hamsters, but not in the eluates of hamster kidneys. These results indicate that CMA is present in circulating immune complexes in infected hamsters. The presence of CMA in kidneys from the same hamsters suggests a possible role for circulating antigens in immune-complexed form in the aetiology of glomerulonephritis in S. mansoni infection.