POTENTIATION OF PHYTOHEMAGGLUTININ STIMULATION OF LYMPHOID-CELLS BY LITHIUM

Stimulation of hamster lymph node cells, splenocytes and thymocytes by the mitogen phytohemagglutinin-P (PHA) was found to be greatly enhanced by addition of 1-10 mM LiCl to the cultures. Lithium enhanced stimulation, as determined by [3H]TdR incorporation, only if added within the first 24 h of culture. The enhancing effect of lithium was specific for this monovalent cation since equivalent concentrations of KCl or NaCl did not induce a similar effect on [3H]TdR incorporation. The divalent cations Mg2+ (1-10 mM) and Ca2+ (1-1.6 mM), also had an enhancing effect on PHA stimulation. However, addition of Li+ to cultures enhanced with Mg2+ and/or Ca2+ led to an additional potentiation of the response to PHA. These results suggest that Li+ modifies a unique early event during stimulation of lymphoid cells by this mitogen. © 1979.