Can insulin antibodies of diabetic patients distinguish human insulin from porcine insulin?
We examined antisera from patients treated with bovine-porcine mixture (hereafter referred to as bovine/porcine), porcine or human insulin, and compared their binding affinities to human insulin with those to porcine insulin. Patients treated with bovine/porcine insulin developed antisera with a higher affinity to porcine insulin compared with that to human insulin in five of nineteen cases. Furthermore, three of these five antisera had a comparable affinity to bovine and porcine insulin and appeared to recognize the amino acid residue at B-30. Treatment with porcine or human insulin, on the other hand, did not result in any significant difference in the affinity to porcine and human insulin in twenty-three patients. These results indicate the significant role of B-30 amino acid residue as an antigenic determinant, and suggest that the amino acid sequence of the A chain of bovine insulin may contribute to the development of antibody recognizing B-30 amino acid residue.
