THE ANTIGENIC LOCI OF INSULIN

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Abstract
Insulin exhibited some cross-reactivity with the isolated S-sulfo A- and B-chains in the passive cutaneous anaphylaxis test. The synthetic peptides A1–9, A10–21, and A1–21gave a passive cutaneous anaphylactic reaction with guinea pig antiserum to natural A-chain, whereas high levels of A10–21and A1–21could also inhibit a subsequent insulin challenge from reacting with antiserum to insulin. The synthetic peptides B1–8, B9–30, B24–30, and B1–30reacted with antiserum to natural B-chain but high levels of peptides (B2–8)2, B9–14, and (B17–23)2were inactive. The symmetrical double peptide (B1–8)2reacted with guinea pig antiserum to intact insulin as well as with antiserum to B-chain and certain sera from insulin-resistant diabetic patients. The results indicated that injection of ox insulin into guinea pigs caused production of anaphylactic antibodies mainly towards antigenic loci in the regions A10–21and B1–8of the insulin molecule, whereas antigenic determinants in the regions A1–9and B24–30were less important.