HDS: Establishment of a New Cell Line from a Hairy Cell Leukemia Patient with Resistance to Alpha-Interferon Therapy.

A new cell line, designated "HDS", was established in a suspension culture derived from the peripheral blood of a patient with hairy cell leukemia (HCL) who developed clinical resistance to alpha-interferon (aIFN) therapy. The patient exhibited a clinical picture characteristic of HCL, including splenomegaly, cytopenias, and tartrate-resistant acid phosphatase (TRAP)-positive "hairy" cells in blood and marrow. Chromosomal studies revealed that the cultured cells possess the chromosomal abnormality +12. Cytochemical and immunologic studies show the HDS cell line had the phenotype of a B-lymphocyte. HDS cells expressed the HLA-DR and CD19 surface antigens, but were negative for early B (CD10) and T (CD2, CD3) cell markers. The cells are also negative for other T-cell, granulocytic and monocytic markers and for typical HCL markers such as CD11c and CD22. However, the expression of these antigens was induced by in-vitro treatment of the cells with the differentiation-inducing agent tetradecanoyl phorbol acetate (TPA). Ultrastructural analyses of the cultured cells revealed a display of surface microvilli mixed with ruffles in a classical hairy cell pattern. It is therefore highly likely that the HDS cells represent HCL cells in an atypical stage of differentiation.