Initiation of the blastogenic response of lymphocytes by hyperoptimal concentrations of concanavalin A

摘要

AbstractThe blastogenic response of human lymphocytesin vitroto hyperoptimal concentrations of concanavalin A (Con A) has been studied by means of volume spectroscopy (measuring cellular and nuclear volume), flow cytofluorometry (measuring cellular DNA content) and incorporation of 3Hthymidine (3HdThd). The optimal Con A dose with respect to 3HdThd incorporation was about 30 u, g/ml. In cultures given hyperoptimal doses,e.g.100 μg/ml, 3HdThd incorporation was strongly inhibited, whereas the number of cells entering S‐phase and significantly increasing their cellular and nuclear volume was considerably larger than with 30 μg/ml. With 200 μg/ml Con A, which induced negligible 3HdThd incorporation, the percentage of responding cells was even larger. Hence, doses of Con A, which were hyperoptimal with regard to 3HdThd incorporation, induced blastogenic response, including DNA synthesis, in a larger percentage of the cells than did the optimal dose. However, in cultures with hyperoptimal Con A doses, the progression of the cell cycle stagnated mainly during S‐ and G2‐phase and few cells completed mitosis. Thus, the blocking effect of hyperoptimal doses was not confined to any particular point of the cell cycle. The reduced 3HdThd incorporation, seen with hyperoptimal doses, is attributed partly to a failure of this assay under such co