Optimizing the Lymphocyte Transformation Test in Whole Blood. II. Kinetics of Thymidine Incorporation

Abstract From the 2nd day of incubation on, the thymidine incorporation per incubated lymphocyte increased exponentially with time. The duration of the exponential growth phase was inversely correlated with the number of cells. Under optimum conditions the average time for the doubling of thymidine incorporation (Ti) was 15.7 h. Ti after 1 day of incubation was taken as an equivalent for the number of proliferating cells. It was estimated that less than 20% of the incubated lymphocytes are stimulated by PHA under optimum conditions. In Ficoll-separated mononuclear cells, the percentage of cells stimulated by PHA was lower than in whole blood; the proliferation rate was not decreased.