Evaluation of lymphocyte activation by flow cytometric determination of interleukin-2 (CD25) receptor.

Lymphocyte response to mitogens is a habitually-used test in the evaluation of the immune system. The usual method with [3H]thymidine yields results which are difficult to interpret. In our search for an alternative, we examined the feasibility of determining T lymphocyte activation by measuring interleukin-2 receptor (CD25) expression with flow cytometry. We found a good correlation between CD25 molecule expression and the dose of phytohemagglutinin, however, there was no correlation between disintegrations per minute produced by [3H]thymidine uptake and the percentage of CD25 expressed by cells.