Effects of polycationic compounds on mitogen stimulation.

The effects of polycations added to phytomitogen stimulated human lymphocyte cultures have been studied. Within certain dose ranges all polycations tested gave rise to augmented thymidine uptake in mitogen stimulated cultures. The optimum enhancing concentrations of polycations was depending on the serum concentration in the culture medium. This was found to be due to two types of interactions: (a) Interference with mitogen binding serum factors, (b) Reaction with immunosuppressive serum proteins. Suggestive evidence for an affect of polycations also directly on the cells was found by pretreatment and cell density experiments. The direct effect on cells was found not to be due to monocyte bypass or to activation of non-T cells by the mitogen. It is pointed out that effect of chemicals on in vitro immunresponses have to be considered in relation to the charge properties of the compound.