Recovery of hematologic competence without engraftment following attempted bone marrow transplantation for aplastic anemia: Report of a case with diffusion chamber studies.

An 18-year-old male with severe aplastic anemia associated with hepatitis was prepared for bone marrow transplantation with cyclophosphamide (50 mg/kg/day) for 4 consecutive days. He then received 3.47 X 10(8) nucleated bone marrow cells per kilogram of body weight from his HL-A identical sister by intravenous infusion. Although subsequent karyotyping showed that engraftment was not achieved, prompt hematologic recovery ensued by the third week post-transplant. Diffusion chamber culture of the patient's bone marrow stroma, obtained prior to cyclophosphamide therapy, was carried out. A prompt increase in the number of cells in the chambers was observed. A differential cell count of the contents was similar to that seen when normal bone marrow is cultured in a similar manner.