Abstract

Objective: Type 1 diabetes results from an immune mediated destruction of β cells, most likely to be mediated by T lymphocytes, but the sensitivity, specificity, and other measures of validity of existing assays for islet autoreactive T cells are not well established. Such assays are vital for monitoring responses to interventions that may modulate disease progression.

Research Design and Methods: We studied the ability of cellular assays to discriminate responses in patients with Type 1 diabetes and normal control subjects in a randomized blinded study in the US and UK. We evaluated the reproducibility of these measurements overall and to individual analytes from repeat collections.

Results: Responses in the cellular immunoblot (CI), UK-ELISPOT, and T cell proliferation (TCP) assays could differentiate patients from control subjects with odds ratios of 21.7, 3.44, and 3.36, respectively, with sensitivity and specificity as high as 74% and 88%. The Class II tetramer and US ELISPOT assays performed less well. Despite the significant association of the responses with Type 1 diabetes, the reproducibility of the measured responses, both overall and individual analytes, was relatively low. Positive samples from normal control subjects (i.e. false positives) were generally isolated to single assays

Conclusions: The CI, UK-ELISPOT, and TCP assays can distinguish responses from patients with Type 1 diabetes and healthy control subjects. The limited reproducibility of the measurements overall and of responses to individual analytes may reflect the difficulty in detection of low frequency of antigen specific T cells or variability in their appearance in peripheral blood.