The effect of cytochalasin B on effector--target cell interaction. Quantitative and ultrastructural study.

Interaction between pokeweed mitogen-stimulated secondary lymphocytes (PWM-lymphocytes) and target fibroblasts resulted in over 80 per cent adherence of the sensitized lymphocytes to the target cells. Adherence is by pseudopod penetration into target fibroblasts. The only lymphocyte cellular components found in the contact region were microfilaments. Cytochalasin B completely inhibited the specific adsorption of the PWM-secondary lymphocytes to the target cells. What adhesion did take place in the presence of cytochalasin B was found to be nonspecific. Ultrastructurally, the contact between lymphocyte and target cells was altered by the drug, when pseudopods were not observed. Possible effects of cytochalasin B on lymphocyte-mediated cytolysis, mainly by its effect on microfilament function, is discussed.