Increased killer cell activity in insulin dependent (type 1) diabetes mellitus.

Antibody dependent cell mediated cytotoxicity in relation to the levels of circulating killer cells was investigated in 16 newly diagnosed classical insulin dependent (Type 1) diabetics, 11 islet cell antibody positive non diabetic children with at least one HLA haplotype in common with their diabetic sibling, and in 15 normal controls. Antibody dependent cell mediated cytotoxicity was evaluated using, as target, 51Cr labelled human 0+ erythrocytes sensitised with an anti-CD antiserum. Killer cells were measured by the low affinity E-rosetting cell technique. Increased killer cell levels (greater than normal mean + 2SD) were accompanied by a significant enhancement in antibody dependent cell mediated cytotoxicity both in newly diagnosed diabetics (p less than 0.05) and in unaffected siblings (p less than 0.01). These preliminary results indicate that raised antibody dependent cell mediated cytotoxicity is a feature of insulin dependent diabetes at diagnosis and suggest that active B cell damage might be occurring some time before the onset of clinical symptoms.