Phorbol esters and hairy cell leukemia: effects on cell morphology and surface membrane features and comparison with other B cell leukemias.

Hairy cell leukemia (HCL) mononuclear cells were incubated with the phorbol ester TPA in an attempt to induce further maturation and were compared with B cell chronic lymphocytic leukemia, prolymphocytic leukemia, and non-Hodgkin's lymphoma cells. Morphology, surface features, membrane markers, tartrate-resistant acid phosphatase, and Ig secretion were examined. HCL cells spread and adhered firmly after TPA, producing elongated filopodia. Cells still retained ribosomal lamellar complexes, and increased numbers of dense bodies were seen. TPA enhanced the adherent and phagocytic properties of HCL cells, producing a modest increase in the expression of membrane Ig, GP-70, and Leu-M5 markers, tartrate-resistant acid phosphatase, and Ig secretion. Other neoplastic B cells behaved differently, forming readily detachable clumps without elongated filopodia. Maturation to plasma cells and hairy cell features were readily evident in all cases. These differences in growth patterns were consistent and may be used to distinguish HCL from other B cell neoplasias.