Reaction patterns of islet-cell autoantibodies in Macaca nigra

Circulating islet-cell autoantibodies (ICAAs) that reacted specifically with cytoplasmic components have been found in the blood of prediabetic Macaca nigra. The three distinct reaction patterns observed involved the majority of islet cells throughout the islet; a moderate number of cells, mainly at the islet periphery and around the vasculature; and a few cells scattered throughout the islet. Pancreas sections incubated with sera containing ICAAs followed with peroxidase-conjugated antibody were then reacted with anti-insulin, antiglucagon, or antisomatostatin antisera. The pattern associated with most of the islet cells was shown to be reactive to beta cells and was termed B-ICAA; the pattern with cells at the periphery was identified as alpha cells (A-ICAA); and the scattered cells contained somatostatin (D-ICAA). None of the three islet hormones were able to block ICAA reaction after overnight incubation, so the ICAAs are not anti-islet hormone antibodies. The varied reactions with antigens of different secretory cells indicate release of a variety of immunogens from islet cells as they necrose and cause the formation of different ICAAs.