The measurement of lymphocyte size and thymidine uptake in comparative response to mitogen stimulation in vitro

Measurements of thymidine uptake and cell size with the Coulter ZBI Counter and C-1000 channelyzer were found to be comparable for mitogen-stimulated lymphocytes. These two technics show a discrete relation with correlated regions of high and low response. Electronic sizing was correlated linearly to microscopic sizing of lymphoblasts. The reproducibility of radiolabeled and electronic sizing measurements were similar and significantly better than that of manual microscopic sizing. The distribution of lymphocyte sizes after two or three days in culture with mitogen was found to be bimodal. This facilitated the direct detection of stimulation responses with the ZBI counter.