Improvement of the in vitro T cell proliferation assay by a modified method that separates the antigen recognition and IL-2-dependent steps.

T cell activation is commonly assayed in vitro by measuring the proliferative response of primed cells to an antigenic stimulus. We have modified the conventional form of this assay by dividing up the response into two stages. During the first stage, antigen drives the specific expression of IL-2 receptor expression. This phase is carried out in the presence of homologous mouse serum, in order to reduce non-specific responses to a minimum. During the second phase, proliferation of these activated T cells is driven by the addition of excess exogenous IL-2. This modified form of proliferation assay significantly increased the signal to noise ratio which can be attained, and is of particular value when looking at the T cell response to weak (e.g., cross-reactive) antigens, or low concentrations of antigen.