Interaction of Epstein‐Barr virus with leukaemic B cells in vitro . II. Cell line establishment from prolymphocytic leukaemia and from Waldenström's macroglobulinaemia

Leukaemic B‐cell populations were prepared from six patients with high‐count prolymphocytic leukaemia (PLL) as well as from one patient with Waldenström's macroglobulinaemia (WM) in frankly leukaemic phase, and their response to in vitro Epstein‐Barr (EB) virus infection was monitored in terms of expression of the virus‐associated nuclear antigen EBNA and of virus‐induced transformation to continuous cell lines. The individual leukaemic populations, tested on several occasions, gave reproducibly different responses one from another which were not obviously related to differences either of surface immunoglobulin phenotype or of immunoglobulin secretor status in vivo . After infection, four out of six PLL populations showed either transient or a more persistent expression of EBNA, always involving a minority of the cells, with no evidence of any virus‐induced transformation up to six weeks. In contrast, two out of six PLL samples as well as the WM sample rapidly gave rise to EBNA‐positive cell lines which, on the evidence both of restricted immunoglobulin class expression and of abnormal marker chromosomes, were clearly derived from the leukaemic cells. Further comparative studies of such leukaemic B‐cell populations may help to define host cell components necessary for the triggering of EB‐virus‐induced cellular transformation.