Whole-blood proliferation assay for autoimmune thyroid disease: Comparison to density-gradient separated-peripheral blood lymphocytes

Autoimmune thyroid diseases feature prominent cellular infiltration of the thyroid gland as well as autoantibody production to thyroid antigens. The most common assay to evaluate cell-mediated immunity is based on incorporation of tritiated thymidine into proliferating T cells after stimulation by the test antigens. In the past, cell proliferation assays of thyroglobulin (Tg) using peripheral blood mononuclear cells (PBMC) of individuals with autoimmune thyroid diseases required large quantities of blood and specialized separation techniques, and have not yielded high counts or high stimulation indices. We therefore developed a proliferation assay using less than 5 mL of whole blood and compared proliferation of cells in whole blood to that using PBMCs separated by density gradient centrifugation. We also determined if responses could be enhanced by addition of interleukin-2 (IL-2) to the cultures. We found that an IL-2-stimulated proliferation assay to Tg using diluted whole blood is superior to the separated cell assay in detecting Tg-specific T-cell proliferation in autoimmune thyroid disease patients. Further refinement of this technique and larger trials may confirm its value for clinical investigation and special diagnostic applications.