Phagocytic Potential of Hairy Cells

Abstract

The hairy‐cells (HC) of 10 patients with hairy‐cell leukaemia were studied with several techniques to evaluate their phagocytic potential. Mononuclear cells from normal donors and from patients with acute monocytic leukaemia served as controls. Light microscopically HC seemed to have ingested bacteria or latex particles. Treatment of the cells with lysostaphin, an enzyme that kills extracellular Staphylococcus aureus, showed that almost all ‘ingested’ bacteria were extracellular. Lanthanum nitrate, added during the fixation procedure for electron microscopy, stained both the outer cell membrane and the membranes of the ‘phagosomes’ of the HC, also indicating that the ‘ingested’ particles were extracellular. HC showed no increased oxygen consumption on exposure to bacteria in the presence of serum. Furthermore, HC showed no lysozyme or peroxidase activity, whereas non‐specific esterase activity was much weaker than in monocytes. These findings, which show that HC are essentially non‐phagocytic, constitute strong evidence against a monocytic origin of the malignant cells of hairy‐cell leukaemia.

Identification of uniquely expressed transcription factors in highly purified B‐cell lymphoma samples

“…Furthermore, TFs with direct or indirect tumor suppressor function were found in each BCL subgroup as well as other individual genes, explaining functional features previously reported to be associated with the specific subgroup. Amongst others, HCL, shown to be a distinct group in all analyses performed, has, for example previously been shown to occupy phagocytic capacity [55,56]. This is reflected in the distinct gene expression profile observed for HCL cells as compared with other BCLs and nonmalignant B-cells using both a focused list of TFs and unselected genes.…”

Hairy cell leukaemia: biological and clinical overview from immunogenetic insights

“…In the past, the tumour clone had been initially thought to be derived from a cell transformed from the reticuloendothelium, since HCs conserved the morphology and functions resembling those of the monocytoid/ macrophage system [7][8][9][10]. HCs were also shown to act as 'accessory cells' that induce proliferation of T cells in vitro [11] and have phagocytic activity and phenotypic features, including the expression of FcRs, CD11c integrin and CD1a, that resemble those of monocytes [10,[12][13][14][15].…”