Erysipelas arthritis in swine: concentrations of complement and third component of complement in synovia.

Concentrations of hemolytic complement and of 3rd component of complement were determined in serums and in synovia of normal and arthritic joints in swine affected with arthritis experimentally produced by the inoculation of Erysipelothrix rhusiopathiae. Mean concentrations of complement in arthritic joints were increased from 24.7 to 37.5 50% hemolytic units of complement per milliliter. Third component of complement, expressed as a percentage of the serum concentration, was increased from a mean of 16.9 (normal joint synovia) to a mean of 27.1 (arthritic joint synovia). Also, fast-migrating conversion products of 3rd component of complement were not detected in synovia from arthritic joints. These results are interpreted as indicating a relatively less important role for immune complexes in the pathogenesis of erysipelothrix arthritis than is described for rheumatoid arthritis in persons.