Ultrastructure of antibody dependent cellular cytotoxicity in HSV 1 infected and uninfected Chang liver cells.

The binding and ultrastructural features of antibody dependent cellular cytotoxicity (ADCC) mediated by human peripheral blood lymphocytes were studied in herpes simplex virus type I (HSV-1) infected Chang liver (CL) cells plus human anti-HSV-1 serum, and in uninfected CL cells plus guinea pig anti-CL antiserum. Non-cytolytic controls included target cells treated with normal serum in place of sensitized targets and heat shocked lymphocytes instead of normal lymphocytes. By transmission electron microscopy, target cell membranes were either broadly indented by effector cells or locally invaginated by means of effector cell filopodia. In neither case did the indentation appear to break the plasma membrane of the target. Control preparations showed only non-indented areas of simple membrane contact. By scanning electron microscopy, the effector lymphocytes in both the active ADCC and normal serum control preparations had a sparse distribution of short microvilli over their surfaces. The majority of heat shock control lymphocytes appeared normal, but 12-20% demonstrated surface patches devoid of microvilli. The hypothesis that ADCC may involve a three-step process is discussed.