Detection of islet cell antibodies by a microcytotoxicity method.

A microcytotoxicity test for antibodies against islet cells (ICA) is described. Sera from patients with insulin-dependent diabetes, their healthy first degree relatives, and normal controls, genotyped for HLA-A, -B and -DR, were tested by 4 different methods. Cytoplasmic ICA and complement fixing ICA were detected by indirect immunofluorescence with human pancreas sections, and cytotoxic complement dependent ICA and surface ICA were tested against murine beta cell suspensions. Strong correlation was found between cytotoxic and surface antibodies (P less than 10(-7). The technique described is appropriate for use in the screening of large numbers of sera.