The mitogenic effects of phytohemagglutinin on stable cell strains in vitro have been studied by counting the multiplication of cells seeded in T-30 flasks. The treatment for 6 days with PHA-M or -P to the HeLa, human amnion and McCoy strains was not found to enhance growth of these cells.
PHA, known to have mitogenic effects on peripheral lymphocytes in tissue culture systems, has not shown its , stimulative effect on strain cells which have a gross proliferative ability.
An inhibitory effect of PHA-P on rapidly growing cells in vitro was demonstrated, since disturbance of cell attachment to the glass was occurred in an initiation of the culture. Concentration of PHA-P required for 50 per cent inhibition of the HeLa cell growth was approximately 0.1 per cent in culture medium, and did not differ significantly with other two strains.