THE ANTIGENIC LOCI OF INSULIN

Abstract

Insulin exhibited some cross-reactivity with the isolated S-sulfo A- and B-chains in the passive cutaneous anaphylaxis test. The synthetic peptides A 1–9 , A 10–21 , and A 1–21 gave a passive cutaneous anaphylactic reaction with guinea pig antiserum to natural A-chain, whereas high levels of A 10–21 and A 1–21 could also inhibit a subsequent insulin challenge from reacting with antiserum to insulin. The synthetic peptides B 1–8 , B 9–30 , B 24–30 , and B 1–30 reacted with antiserum to natural B-chain but high levels of peptides (B 2–8 ) 2 , B 9–14 , and (B 17–23 ) 2 were inactive. The symmetrical double peptide (B 1–8 ) 2 reacted 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 A 10–21 and B 1–8 of the insulin molecule, whereas antigenic determinants in the regions A 1–9 and B 24–30 were less important.