Yehudit Stupp

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 Freunds 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.

Further studies on the immunogenicity of d-amino acid polymers

Abstract Racemic polymers, composed of d -amino acids and decreasing amounts of l -amino acids (ranging from 42% to 3%) induced antibody formation in rabbits and delayed hypersensitivity in guinea pigs. A polypeptide composed exclusively of d -amino acids, p( d -Tyr, d -Glu, d -Lys), provoked an immune response in rabbits and in guinea pigs. In this case, the dose used for immunizing rabbits was 100 μg antigen in complete Freunds adjuvant (CFA). Antisera against either the racemic polymers or the d -amino acid polypeptide were negative in the passive cutaneous anaphylaxis (PCA) test. Antibodies against one of the racemic polymers and against the polypeptide composed exclusively of d -amino acids, were isolated by means of specific immunoadsorbents and characterized. Purified antibodies gave positive PCA reactions with homologous antigens.

Specificity of delayed reactions to hapten-polypeptide conjugates.

Abstract Guinea pigs sensitized with p -azobenzenearsonate conjugates of polytyrosine, poly Lys 51 Tyr 49 , poly Glu 52 Tyr 48 and poly Ala 34 Glu 36 Tyr 30 , showed delayed cross-reactions with p -azobenzenearsonate conjugate of bovine serum albumin. When conjugates of poly-peptides containing other haptens such as p -azobenzoate, p -azobenzenesulfonate and p -nitrophenylazo were used as sensitizing antigens, no delayed cross-reactions were observed with the corresponding hapten-bovine serum albumin conjugates, in conformity with the “carrier-specificity” known to exist in most delayed hypersensitivity reactions.