Immuno-fluorescence and immuno-electron microscopy on EBV-associated membrane antigen of a nasopharyngeal carcinoma derived lymphoblastoid cell line (LY-28)

The Epstein-Barr virus-induced, cell membrane antigen (MA), was localized on a nasopharyngeal carcinoma (NPC)-derived lymphoblastoid cell line by indirect immuno-fluorescence and immuno-electron microscopy after applying a Burkitt serum (Abwao), with anti-MA and anti-VCA reactivity. The immuno-fluorescence and immuno-electron microscopic observations indicated a dotted, patchy or segmental labelling of the surface of cells incubated with Abwao serum under conditions (4°C) minimizing redistribution of membrane-bound antibodies. At the ultrastructural level, the most extensive surface labelling was seen in a small percentage of cells, which had characteristically altered nuclei and contained intranuclear and/or cytoplasmic viral particles. A larger number of cells showed smaller patches of membrane labelling, and in these cells no viral particles or degenerative changes were observed. Extracellular viral particles, usually associated with the surface of cells, were more heavily labelled in preparations treated with the Abwao serum as compared to treatment with a heterologous antiserum. Some cells appeared to engage in active uptake of membrane associated virus particles by endocytosis.