Effects of cytochalasin B on fibroblasts,lymphoid cells,and platelets revealed by human anti-actin antibodies

Human antibodies against actin revealed on smeared lymphoblastoid cells a strong staining of numerous microvilli of different lengths extending from the cell surface. Smeared human platelets stained by anti-actin serum showed a bright cytoplasmic fluorescence and projections extending from the surface. Human fibroblasts spread on glass were multi-shaped, and anti-actin serum revealed brightly stained fibers running through the cells. After treatment with cytochalasin B, all types of cells investigated became rounded up, and surface projections could not be demonstrated. The staining pattern indicated a redistribution of the cellular contractile proteins after cytochalasin B treatment. Cytochalasin B did not impair the antigenicity of actin, since presence of the drug did not influence the antibody absorbing capacity of actin.Culture of lymphoblastoid cells and human fibroblasts in the presence of colchicin did not influence the staining pattern of actin antibodies.