Immunoglobulin and complement deposits in the skin and circulating immune complexes in scabies.

Sixteen patients with papulovesicular, 6 with nodular and one with a Norwegian scabies were studied. Direct immunofluorescence (IF) examination revealed C3 deposits in the skin lesions of 13 of the 18 patients. Among them were all 6 cases with nodular scabies. C3 was found mostly in dermal vessel walls and 3 of the patients also showed IgM and 2 IgA deposits at the same site. No circulating immune complexes were found, with a solid-phase C1q radioimmunoassay (RIA), but HSV- and RSV-RIA methods detected IgM antibodies of rheumatoid factor type in 5 of the 15 sera examined. These results suggest that local complement activation and perhaps also immune complex deposition may by important in the pathogenesis of the papular and nodular skin lesions of human scabies.