Possible transformation of nasopharyngeal epithelial cells in culture with Epstein-Barr virus from B95-8 cells

D P Huang,H C Ho,M Lui,M H Ng

doi:10.1038/bjc.1977.98

Abstract

Explants of fresh biopsy specimens from non-neoplastic nasopharyngeal (NP) mucosa, nasopharyngeal carcinoma (NPC), other tumours (OT) of the head and neck and freshly removed tonsils were treated with an Epstein-Barr virus (EBV) preparation from B95-8 cells and cultured. The mainly epitheloid outgrowths from these infected explants were then compared with those from their respective uninfected controls at 14 days. Growth stimulation occurred with a significantly higher frequency, and the degree of stimulation was generally higher with the infected NP explants than those of the similarly infected explants of other origins. Furthermore, after treatment with the virus preparation, several of the outgrowths from the NP explants showed growth characteristics and cellular morphology typical of those of transformed cells. Light microscopy has shown the changed NP cells to have epithelial characteristics. This is now being verified by electron microscopy, which has so far shown the presence of keratin fibrils and desmosomes in one specimen examined. They are also being examined for the presence of EBV-DNA and EBNA, and other features of transformation, including malignant tendency, by passage through athymic nude mice.

Highlights

Summary.-Explants of fresh biopsy specimens from non-neoplastic nasopharyngeal (NP) mucosa, nasopharyngeal carcinoma (NPC), other tumours (OT) of the head and neck and freshly removed tonsils were treated with an Epstein-Barr virus (EBV) preparation from B95-8 cells and cultured
In an attempt to probe this role we studied the effects of EBV infection in vitro on explants from nonneoplastic nasopharyngeal (NP) mucosal biopsy specimens, using controls consisting of tonsillar mucosa which, like NP mucosa, overlies lymphoid tissue in the Waldeyer's ring, and biopsy specimens from NPC and other tumours (OT) of the upper respiratory and alimentary tracts, all but one of which were carcinomas
Fresh biopsy specimens were obtained from the NP of 20 patients in whom neoplasm had been excluded on clinical and histological grounds, from the primary tumours of 10 patients with NPC and 7 patients with OT (1 adenocarcinoma and 1 well differentiated squamous carcinoma of the floor of the mouth, 1 moderately-to-poorly differentiated squamous carcinoma of the hard palate, 1 well differentiated squamous carcinoma of the soft palate, 1 well differentiated squamous carcinoma of the tonsil, 1 adenoid cystic carcinoma of the pharyngeal surface of the soft palate and 1 Stewart's granuloma of the nasal fossa)

Summary

MATERIALS AND METHODS

(1973) from the culture fluid of B95-8 cells and kept at -70°C for not more than 4 months, was used throughout Infectivity of this virus preparation during the course of the study was assessed at regular intervals by its stimulatory effect on the rate of [ 3H] thymidine incorporation by cord leucocytes and subsequent formation of cell lines. That this effect is virus-mediated is shown by its abolition if the infection was carried out in the presence of human sera with anti-EBV-VCA reactivity, or if the leucocytes were treated overnight before the infection with, and subsequently cultured in the presence of, 100 standard units of human foreskin cell interferon. The mean sizes of the cell outgrowths (mm diameter) from the EBV-infected and control fragments from each specimen were determined after 2-3 weeks in culture

RESULTS

Mean growth

DISCUSSION