Immunoglobulin and complement in tissues of mice infected with Nocardia brasiliensis.

Two weeks after mice had been infected in the footpad with cells of Nocardia brasiliensis, immunoglobulin and C3 deposits were observed in tissue from the inoculation site. Both immunoglobulin and C3 were found in the actinomycotic granules that characterize the mycetoma and in the surrounding inflammatory zones, in which plasma cells were also present. Although anti-N. brasiliensis specificity was evidenced at 14 days postinfection in an eluate of infected tissue by an immunoenzymatic assay, no such antibody was found in the serum until 45 days postinfection. Immune complexes in the lesions, as indicated by the presence of C3, may also contribute to the pathology of the disease.