Characterisation of a new cell line (CJ18) from a patient with 'hairy' cell leukaemia

A cell line (CJ18) has been established from the peripheral blood of a patient with hairy cell leukaemia (HCL) in a leukaemic phase. They grow slowly in large clumps with a doubling time of 3-4 d. 8% show positivity for surface immunoglobulin G and a small percentage (5%) are positive for intracytoplasmic immunoglobulin. They are B1,Ia1 positive and CALL, TdT and OKM1 negative. Although they are Epstein Barr Virus Nuclear Antigen (EBNA) positive they have several features not found in other EBNA positive B lymphoblastoid cell lines which suggest they may be derived from the patient's leukaemic hairy cells. They are strongly positive for tartrate resistant acid phosphatase, esterase positive, contain numerous lysosomes and are able to phagocytose sheep red blood cells after exposure to tetradecanoyl-12, 13-phorbol acetate (TPA). Following exposure to retinoic acid and TPA they adhere to plastic with numerous slender processes, a feature seen in HCL cells.