Morphologic, cytogenetic and virologic studies in vitro of a malignant lymphoma from an African child

A cell line of human lymphoblasts (AL1), derived from a malignant lymphoma involving the jaw of an African child, has been established in a medium containing 20 per cent fetal bovine serum. The cells grow in aggregates in suspension and are morphologically similar to previously described human lymphoma cell lines grown in media containing human serum. The chromosome number distribution was wide, ranging from 40 to 77. The modal number was 46 with a pseudodiploid karyotype. Electron microscopically, herpes‐like virus particles were found in less than 1 per cent of the cells during the first 4 months of culture, but subsequently no cells containing virus particles have been seen. Although the medium was free of human serum which might contain antibodies to many human viruses, numerous and varied attempts to isolate viruses from the cells were unsuccessful. Following the report of interferon production by other cells lines derived from lymphomas of African children, we were able to demonstrate interferon in the supernatant fluids of AL1 cultures. The interferon was demonstrable even when virus particles could no longer be found in the cells electron microscopically. Attempts to serially pass the antiviral activity in the absence of lymphoma cells were unsuccessful. The significance of the interferon production by the lymphoma cells is not known. Cultures of AL1 cells infected with SV40 became SV40 carrier cultures but there were no morphological changes in the lymphoma cells and there was no increase in herpes‐like particles electron microscopically. AL1 cells infected with herpes simplex virus developed degenerative changes, and typical immature and mature herpes particles were seen by electron microscopy in most of the cells. AL1 cultures infected with adenoviruses 7 and 12, vaccinia, reovirus 3 and cytomegalovirus showed no evidence of growth of these viruses in the lymphoma cells and no increase in numbers of herpes‐like virus particles by electron microscopy.