Using a radioisotope labeling technic, the ability of bovine and porcine insulin antigens to induce lymphocyte transformation was tested with cells from the peripheral blood of thirty nondiabetic controls, fifty established insulin-dependent diabetics with no evidence of insulin allergy, and ten newly diagnosed diabetics (five untreated, five insulin-treated for less than three weeks). Lymphocytes from twenty-six (42 per cent) of the diabetics showed significant blastogenesis to bovine or porcine insulin, as compared with two (7 per cent) of controls; the phenomenon was shown by both established and newly diagnosed patients including four who had never received insulin. The results indicate that cellular hypersensitivity to insulin, as judged by an in vitro test, is relatively common in insulin-treated diabetics without in vivo evidence of allergy, and suggest that hypersensitivity may also be present in untreated diabetics.
Lymphocytes from twenty-one of the twenty-six diabetics who responded to intact insulin were further tested using bovine and porcine insulin A chain and bovine B chain as antigens. The A chain of either insulin induced significant blastogenesis in only one diabetic but bovine B chain induced significant blastogenesis in fourteen (67 per cent) of the patients tested. These results suggest that B chain is the major antigenic site determining cellular hypersensitivity to insulin.