THE POTENTIAL IMMUNOGENICITY OF HUMAN INSULIN AND INSULIN ANALOGS EVALUATED IN A TRANSGENIC MOUSE MODEL

Transgenic mice with tissue-specific expression of the human insulin g ene in the beta cells of the pancreas do not produce insulin-specific antibodies when injected with human insulin. Tolerant transgenic mice injected with human or porcine insulin reflect the clinical situation. When injected with bovine insulin the transgenic mice produce antibod ies. The potential immunogenicity of 12 recombinant human insulin anal ogues has been tested in this transgenic model. The analogues were des igned either to prevent hexamer formation or to improve chemical stabi lity or both. The analogues have amino acid substitutions or deletions at residue 8, 10 and 21 in the A-chain and residue 3, 9, 27 and 28 in the B-chain. The results show that substitution of single amino acids in the A-chain loop of human insulin for the corresponding amino acid s in bovine insulin at residues A8 or A10 is sufficient to elicit an a ntibody response in responder mice. Only human insulin analogues with substitutions at residues 8 or 10 in the A-chain elicit antibody forma tion in the transgenic mice, whereas non-transgenic control groups res pond to insulin and all analogues. Antibodies developed against the hu man insulin analogues are cross reactive with recombinant human insuli n. Antibodies developed against an immunogenic analogue could therefor e neutralize both the analogue and the native insulin and thereby aggr avate the patient's condition. This transgenic mouse immunogenicity mo del should be useful as an in vivo model to map immunogenic areas of r ecombinant proteins.