Cell-mediated immunity to insulin and its polypeptide chains in insulin-treated diabectics

35 insulin-treated diabetics and 25 control persons were studied for in vivo and in vitro manifestations of hypersensitivity to insulin and its isolated polypeptide chains. Delayed hypersensitivity reactions were determined by skin testing, and blastogenic conversion tests were done with peripheral blood lymphocytes. None of the controls and 62.9% of the patients gave positive reactions in the blastogenic test, most of these reacted to the intact molecule, fewer patients responded to B chains, and very few responded to A chains. None of the controls and only three of the patients produced positive delayed hypersensitivity reactions to insulin, and all of these were to the intact insulin molecule.