Comparing stimulation of lymphocytes in different samples: Separate effects of numbers of responding cells and their capacity to respond

Abstract

A range of concentrations in culture of human lymphocytes from the peripheral blood has been used to provide information on two major factors contributing to the total response to stimulation with mitogens; these factors are the numbers of responding cells, and the efficiency of these responding cells. The marked effect of cell concentration in culture on the thymidine incorporation of stimulated lymphocytes ranged from a background response to a maximal response mainly over 1 log unit of cell concentration (cells/ml). At higher cell concentrations the measured response fell. Since the absolute number of lymphocytes that respond to stimulation was not known, the relative positions of these responses (incorporations of thymidine) on the axis of concentration of cells were used to estimate the relative numbers of responding cells in different samples. The efficiency of responding cells in different samples was compared using the shape of the response curve with changing concentration of cells. With this approach, frozen and thawed samples of lymphocytes were compared with non-frozen cells and the results indicated a loss in the numbers of responding cells after freezing and thawing, but no change in their efficiency of incorporating thymidine on stimulation with phytohaemagglutinin or allogeneic cells.