A sodium requirement for mitogen-induced proliferation in human peripheral blood lymphocytes

Mitogen-stimulated DNA synthesis in human peripheral blood lymphocytes is dependent on extracellular Na. DNA synthesis was similarly inhibited in:

1. 1. Cells that were suspended in hypotonic media containing decreased extracellular Na.

2. 2. Cells that were suspended in media containing decreased Na and equimolar replacement with choline.

3. 3. Cells that were suspended in media containing decreased Na and equiosmolar replacement with mannitol.

A decreased PHA-induced DNA synthesis was observed at day 3 even when lymphocytes were exposed to low Na for only the first 3 h and then returned to normal levels of Na. Our studies of protein synthesis indicate that the effect of lowered extracellular Na on DNA synthesis and cell division is not due to an initial inhibition of overall protein synthesis. These data suggest that reduced external Na has a significant effect on some specific early event(s) (3 h) in lymphocyte mitogenesis.