Use of phytohemagglutinin to stimulate hematopoiesis in humans.

By DONALD NI. HAYES AND CHARLES L. SPURn P HYTOHEMAGGLUTININ ( PHA),#{176} a mucoprotein extract of the bean Phaseolus vulgaris, has been shown to have mitosis-stimulating effect on cells in tissue culture.1 Although cells from the peripheral blood of normal human do not usually proliferate in tissue culture, the addition of PHA to such cultures causes the initiation of intense mitotic activity among cells of the bymphocytic and monocytic series.2 Administration of PHA to rats by differing routes and dose schedules causes no measurable change in hematocrit, WBC, percentage of lymphocytes in peripheral blood, serum globulin concentration, or histologic pattern of the liver and spleen.3 Many studies have demonstrated the presence in the bone marrow of a pluripotent stem cell which is morphologically indistinguishable from the lymphocyte.4 Because of the presence of lymphocytes which could have pluripotency in the marrow of patients with aplastic anemia, Humble5 elected a trial of PHA in humans with this disease. Initial reports showed a 100 per cent response rate in four patients with marrow hypoplasia secondary to known causes. Because of this report, the following preliminary study was undertaken. This report includes the results of four courses of PHA therapy in three patients: two with aplastic anemia and one with myelofibrosis. While it is recognized that one might question the inclusion of two diseases whch probably differ in their pathogeneses, we felt this was justified in the present study l)ecause all patients satisfied a criterion suggested by the studies mentioned above. Marrow specimens from all 3 patients were examined to insure that barge numbers of lymphocytes and reticulum cells were present. We then felt that mitogenic potency could be demonstrated regardless of the basic cause of marrow depression.