Antibody-dependent cellular cytotoxicity mediated by polymorphonuclear leukocytes and mononuclear cells against HSV-1 infected primary cultures of rabbit corneal epithelium

The roles of rabbit polymorphonuclear leukocytes (PMNL) and mononuclear cells (MC) for the regulation of ocular herpes simplex virus-1 (HSV-1) infection were studied. The antibody-dependent cellular cytotoxicity (ADCC) mediated by PMNL and MC from normal rabbit peripheral blood was assessed kinetically employing a specific 51cr release assay. The HSV-1 infected primary cultures of rabbit corneal epithelium (PRCE) were used as the target cells to obtain a homologous assay system. The PRCE was prepared by an epithelium outgrowth technique and identified by electron microscopy. The expression of the surface HSV-1 antigens on PRCE was examined by indirect immunofluorescent staining; the cell population stained by fluores-cein increased from 40% at 3 hr postinfection (PI) to 100% at 8 hr PI. To determine how early the cytotoxicity occurs, PRCE were infected with HSV-1 for 2 hrs. After 2 hrs, the ADCC was checked every 10 min for the first 40 min and then at 1, 2 and 4 hr of incubation. The cytotoxicity was apparent at 10 min postincubation and reached 46% by PMNL and 40% by MC at 4 hr postincubation (6 hr PI). Significant cytotoxic effect (26% by PMNL and 16% by MC) occurred as early as 3 hr PI. When the one-step growth cycle of HSV-1 was studied in the PRCE, HSV-1 had an eclipse period of 4 hr and a rise period of 8 hr. This suggests that rabbit PMNL and MC have the potential to eliminate the HSV-1 infected rabbit corneal epithelium before HSV matures in the cells.