Hairy Cell Leukaemia: Evidence for the Existence of a Spectrum of Functional Characteristics

Abstract

Functional markers of malignant cells from 14 patients with hairy cell leukaemia were evaluated during a 10 month period to assess the possible existence of sub‐types of the disease. Surface immunoglobulin on the hairy cells from the peripheral blood was studied initially, and again either after trypsinization and culture or after culture alone. Resynthesis of surface immunoglobulin occurred in all 12 patients studied; in four it was clearly monoclonal. Hairy cells from 11 patients were evaluated for their capacity to phagocytose zymosan; in five patients, 25% or more of the hairy cells demonstrated phagocytosis; in five others, less than 10%. One patient had only 13% zymosan phagocytosis initially, but when the study was repeated at a later date, 31% of the hairy cells phagocytosed. There was no phagocytosis of zymosan by malignant cells in 12 patients with a variety of other lymphoproliferative diseases. The percentage of E‐rosettes was correlated inversely with the percentage of circulating hairy cells. EAC‐rosettes were very low in three patients tested, all of whom had a high percentage of hairy cells. The number of tartrate‐resistant acid‐phosphatase‐positive cells varied from patient to patient, and within the same patient at different times. Platelet function was abnormal in six of 11 patients tested, who had a decreased, but not absent, epinephrine response. The significance of these findings in regard to the origin of the hairy cells in hairy cell leukaemia and in regard to the variable clinical course remains to be established.