Studies on Red Cell Aplasia . III . Treatment With Horse Antihuman

A case of pure red cell aplasia, which did not respond to corticosteroids, splenectomy, or cyclophosphamide, has been described. In vitro studies performed with the patient’s marrow showed a much smalter response to erythropoietin than that observed with previous patients who did respond to cyclophosphamide. The patient’s plasma and -yG-globulin fraction inhibited the rate of heme synthesis of normal marrow cells in vitro. The yMglobulins did not inhibit heme synthesis in the same system. The patient was treated with cyclophosphamide and horse antihuman thymocyte gamma globulin (HAHTGG) and had a definite increase in red cell production, but a severe febrile reaction occurred that prevented further use of the HAHTGG. This study indicates that HAHTGG may be of aid in treating severe cases of red cell aptasia when more effective means of minimizing hypersensitivity reactions are devised.