To evaluate possible advantages of human insulin of recombinant DNA origin (HI) in the treatment of diabetic patients, we compared cellular and humoral immunoreactivities of HI and porcine insulin (PI).

Anti-insulin IgE bound equal amounts of 125I-HI and 125I-PI. There was no difference between HI- and PI-stimulated lymphocyte transformation indices.

The binding of 125I-HI with circulating anti-insulin IgG was lower compared with 125I-PI binding (12.1 ± 1% versus 15.4 ± 1.5%, P < 0.001) in 60 insulin-treated cases.

Thirteen sera were selected for high antibody titers and analyzed in detail. In the competitive inhibition assays, a 50% displacement of 125I-PI required a fourfold higher concentration of HI than PI. Although total insulin binding capacities were almost equal, 63 ± 11 nM/L for PI and 60 ± 12 nM/L for HI, the high-affinity antibodies had significantly reduced avidity for HI compared with PI. These differences in avidities suggest that HI may be useful in treatment of immune-type insulin resistance.

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