Serial quantitation of in vitro lymphocyte responsiveness to concanavalin A

Eight normal donors were serially tested over a period of 1 to 7 months for their in vitro lymphocyte responsiveness (IVLR) to 50 microgram of concanavalin A (Con A) per ml. 3H-Thymidine incorporation was monitored by routine scintillation counting and compared to actual numbers of proliferating cells (lymphoblasts) as measured by laser (flow) cytometry. Determination of total cell numbers or lymphoblast numbers was found to be superior (P less than 0.0001 and P less than 0.001, respectively) to 3H-thymidine incorporation as a measure of serial stability.