Immunogenicity and role of size: response of guinea pigs to oligotyrosine and tyrosine derivatives.

Guinea pigs injected with 100 micrograms of p-azobenzenearsonate derivatives of hexa-L-tyrosine, tri-L-tyrosine, or N-acetyl-L-tyrosine amide, in complete Freund's adjuvant, developed, after 10 to 19 days, delayed-type hypersensitivity to these substances. This was shown by skin reactions, followed by the formation of circulating antibodies that were detectable by passive cutaneous anaphylaxis. Experiments with p-azobenzenearsonate-hexa-L-tyrosine labeledwith iodine-131 showed that this substance was bound in vitro to proteins of normal guinea pig serum. Binding was similar with the nonantigenic hexa-L-tyrosine and its p-azobenzoate derivative.