Monitoring of effects of cis-diamminedichloroplatinum (II). Part III. Effect of platinum complexes on PHA-stimulated proliferation of human peripheral blood mononuclear cells in vitro.

The effect of the platinum complexes cis-DDP and CBDCA on the functions of human peripheral blood mononuclear cells (PBMC)--viability, proliferating activity after polyclonal stimulation with phytohemagglutinin is followed in an in vitro study. Both the platinum complexes (at concentrations 10(-5) up to 10(-9) mol/l) inhibit significantly the proliferating activity of PBMC without affecting its viability, i.e. integrity and permeability of the cell membrane structures. As to effectivity, cis-DDP has shown itself a more effective inhibitor of cellular proliferation than CBDCA of which 10-100 times higher concentrations are required to achieve the same inhibitory effect in dependence on the temporal relation to the application of phytohemagglutinin. The highest inhibitory effect is noted when cis-DDP is applied either simultaneously with, or 48 h after PHA, i.e. at the stage of maximum proliferating activity. The results bring support to the assumed mechanism of action of the above platinum complexes--intervention into DNA synthesis. Since the test of blastic transformation of PBMC is held to be an image primarily of the function of T lymphocytes, it may be inferred that platinum cytostatics can affect cell-mediated immunity also in patients.