Host defense deficiency in hairy cell leukemia and its correction by leukocyte transfusion.

A similar defect host defense mechanisms in hairy cell leukemia was defined in two patients. Surface-adherent monocytes were not detected in the peripheral blood nor were monocytes that mediate antibody-dependent cell-mediated cytotoxicity (ADCC) to isoantibody-coated human erythrocytes. In addition, lymphocytes of both patients failed to show blastogenic responses to concanavalin A (Con-A) and pokeweed mitogen (PWM) but showed a vigorous response to phytohemagglutinin (PHA). Other immunologic abnormalities were present but were either moderate in degree or were not present in both patients. In vitro lymphocyte blastogenic responses were fully restored by incubation of patients' leukocytes with a normal donor's adherent monocytes. One patient received daily allogeneic leukocyte transfusion for 4 days. This resulted in complete normalization of monocyte adherence and ADCC that persisted for several months after transfusion and was associated with hemotalogic improvement. Therapy in case 1 resulted in correction of the blastogenic responses to Con-A and PWM. Thus, a host defense defect in hairy cell leukemia has been defined in 2 patients and a preliminary result suggests that therapy with leukocyte transfusions may be useful in the postsplenectomy patient with an infectious complication and should be explored further.