CYTOKINE-BASED HUMAN WHOLE-BLOOD ASSAY FOR THE DETECTION OF ANTIGEN-REACTIVE T-CELLS

The measurement of cytokines produced by activated T cells refines ass essment of cellular immune function and facilitates whole blood T cell assays. The latter approximate conditions in vivo and obviate the nee d to purify blood mononuclear cells. We have investigated the paramete rs of the whole blood assay in humans to standardize and optimize the detection of tetanus-specific T cell cytokine responses. Optimal condi tions include the use of undiluted whole blood, an incubation time of 36-48 h and a minimum of delay between venesection and incubation of t he blood with antigen. Blood should be drawn at a standard time of day to minimize inter-assay variation due to diurnal rhythmicity in cytok ine production. Interferon-gamma or interleukin-2 are specific and rel iable readouts; other cytokines can be measured to further characteriz e the T(H)1 and T(H)2 elements of the T cell responses, although tetan us-stimulated IL-4 production is detected in only a minority of health y individuals. The whole blood assay is a potentially valuable tool fo r assessing cellular immune function and screening for antigen-reactiv e T cells in humans.