Type 1 diabetes results from T-cell-mediated destruction of β-cells, but the sensitivity, specificity, and other measures of validity of existing assays for islet autoreactive T-cells was not well established at the time of this study. Such assays are vital for monitoring responses to interventions that may modulate disease progression.

The following T-Cell Assays were conducted in individuals with type 1 diabetes, as well as those without type 1 diabetes: Cellular Immunoblot Testing, T-Cell Proliferation Assay, Tetramer Assay, and Cytokine ELISpot Assay. Biochemical autoantibody and islet cell antibodies assays were performed to confirm the presence of type 1 diabetes. Genetic testing was also done to learn more about the T-cell assays.

To determine the ability of T-cell assays to identify differences in responses from participants with type 1 diabetes compared to normal control subjects, and to compare four different laboratory tests which examine T-cells to determine whether the measurements are quantitatively reproducible.

The sensitivity (proportion of patients with type 1 diabetes who test positive) and specificity (proportion of control subjects who test negative) of each assay was evaluated.

Eligible subjects were diagnosed with type 1 diabetes within one year of the first study visit, between 8 and 35 years old and weighed at least 40 kg. Control subjects without type 1 diabetes could not have a first or second degree relative with the disease. Exclusion criteria included major illness, steroid medication use, and pregnancy or breast feeding in female subjects.

The Cellular Immunoblot Testing, Cytokine ELISpot Assay, and T-Cell Proliferation Assay can distinguish responses from patients with type 1 diabetes and healthy control subjects. Indeterminant specimens for which the assay did not provide a clear positive or negative response were frequent with the tetramer assay. 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.