Specific suppression of delayed hypersensitivity skin reactions to collagen in guinea-pigs after immunization with collagen and Freund's incomplete adjuvant.

Partial suppression of cutaneous delayed hypersensitivity reactions to collagen in guinea-pigs was induced by pre-immunization with collagen and FIA. This suppression is specific since: (a) pretreatment with OA and FIA or FIA alone did not cause suppression of skin reactions to collagen; (b) suppression was observed only if the collagen used for pretreatment was from the same species as that employed for sensitization for delayed hypersensitivity reactions; and (c) animals with depressed skin reactivity to collagen reacted normally to PPD. The suppression is not mediated by inducible, circulating antibodies to collagen since: (a) antibody titres measured by passive haemagglutination did not correlate with the degree of suppression; (b) suppression was observed with collagen in random coil conformation which sensitizes guinea-pigs for delayed hypersensitivity skin reaction but does not induce antibodies to denatured collagen; (c) best suppression was obtained if the animals were pretreated with collagen and FIA 3 days before the sensitizing injection; and (d) passively transferred antibody from animals with suppressed skin reactivity did not suppress skin reactivity of animals made hypersensitive to collagen by injection of collagen and FCA.