Cell lines derived from a human myelomonocytic leukaemia

Summary. Two cell lines have been isolated from separate samples, taken at the same time, from the peripheral blood of a case of myelomonocytic leukaemia. One of these (CESS-B) is a typical B cell line obtained after treatment of the peripheral blood white cells with Epstein-Barr virus (EBV). The second line (RC-2) is a monocyte-macro-phage type, originally isolated by 5 months continuous culture in the presence of colony stimulating factor (CSF). Subsequently, after further culture, this line has become autonomous (RC-2A), no longer requiring CSF for maintenance of proliferation, whilst retaining the characteristics of the original line.