Immune complexes in type I diabetics with persistent islet cell antibodies.

The sera of 33 type I diabetics found to have pancreatic IgG antibodies to the cytoplasm of pancreatic islet cells (ICAb) at three or more years after diagnosis were tested for immune complexes (AgAb), insulin antibodies and thyroid and gastric cytoplasmic antibodies, and the subjects were HLA typed. Sera from 69 insulin treated diabetics of comparable duration of disease and without ICAb at the time of study were also included in the investigation. The prevalence of AgAb in patients with persistent ICAb was found to be 52% in comparison with 19% of ICAb negative diabetics (p < 0.001) and 10% of normal blood donors (p < 0.0005). AgAb positivity was increased, but not significantly, in HLA-B8 positive compared to B8 negative ICAb persisters. There was a significant negative correlation between AgAb levels and insulin antibody titres. Circulating AgAb were not significantly correlated with the presence of either thyroid or gastric cytoplasmic antibodies.