Hairy cell leukaemia: effects of phorbol ester on cell morphology and adherence and comparison with other B-cell neoplasias.

This report documents phorbol ester-induced changes in cell morphology in 9 patients with hairy cell leukaemia (HCL) and contrasts them with those obtained in cells from 20 patients with B-type chronic lymphocytic leukaemia (CLL) and non-Hodgkin's lymphoma in leukaemic phase (NHL). The phorbol ester caused hairy cells to adhere strongly and produce thin elongated cytoplasmic extensions. Other cells showed marked surface ruffling, and contained increased numbers of phagolysosomes, although cells still retained ribosomal lamellar complexes. This in vitro growth pattern differed from that observed in B-CLL and NHL cells, which readily detached in clumps with minimal adherence. CLL and NHL-cells did not show macrophage features but developed plasmacytoid and hairy cell-like features. It is suggested that these different growth patterns may aid in distinguishing HCL from other B-cell neoplasias.