Hairy cell leukemia: cellular characteristics including surface immunoglobulin dynamics and biosynthesis.

Hairy cell leukemia (HCL) is caused by the proliferation and accumulation of morphologically characteristic cells whose cell line of origin (lymphocyte versus monocyte) has not been determined. In an attempt to determine the cell line from which these cells are derived. we studied the cells from the peripheral blood and spleens of 6 patients with HCL for their cytochemical. immunologic, surface. and functional properties. Clinically the patients were similar to others reported with HCL. with some beneficial responses to splenectomy. Both the peripheral blood cells and spleen cells from these patients had tartrate-resistant acid phosphatase and lacked nonspecific esterase. They failed to rosette with sheep red blood cells (SRBC). C3-coated RBC. or anti-D-coated SRBC. Intense surface fluorescence was produced by fluoresceinlabeled anti-immunoglobulin reagents. and capping rapidly occurred . Reincubation following capping or trypsinization and restaining with anti-immunoglobulin reagents showed the reappearance of monoclonal immunoglobulin. The pattern of immunoglobulin synthesis and release was demonstrated directly by 3H-leucine incorporation into specific immune coprecipitable immunoglobulin and was similar to that of normal B lymphocytes. The cells had a low labeling index but had modest phagocytic ability. The unequivocal demonstration of endogenous immunoglobulin synthesis establishes these cells as Blymphoid in nature. However, they may represent a particular B-lymphocyte subset originating in the spleen and having phagocytic ability.