[The effect of cytostatic drugs on immunocompetent cells]

The cytotoxic and immunosuppressive effects of cytostatic drugs on immunocompetent cells and other cells of the haematopoietic system are known. The application of these drugs leads to irreversible bindings on and inside the DNA or on enzymes. In vitro studies demonstrate that these reactions occur at concentrations of about 100 micrograms/ml-10 ng/ml and a cell number of 10(6) MNC/ml. However, the same drugs show immunostimulating activities at much lower concentrations. Under such conditions the drugs cannot penetrate into the cells. Probably a drug-membrane-receptor-complex is formed and via signaling pathway certain gene regions are activated to produce cytokines and other regulator molecules. An understanding of these mechanisms is essential to the development of novel therapy strategies.