Long-term study of chimaerism in bone marrow transplantation recipients for severe aplastic anaemia.

We used minisatellite probes to analyse by DNA fingerprints the long-term engraftment (median 4.3 years, range 1-2) of 21 bone marrow transplantation recipients for severe aplastic anaemia. Patients received their graft from histocompatible siblings. They were conditioned with cyclophosphamide (150 mg/kg) and a 6GY thoracoabdominal irradiation and did not have ex-vivo T cell depletion of marrow donor. DNA was extracted peripheral mononuclear cells and analysed by Southern blotting with 32P-labelled single-stranded RNA probes. Seven out of 21 donor-recipient pairs were sex-mismatched and additionally studied with a probe detecting a male specific repeated sequence on the Y chromosome. Red cell surface phenotype was also used as marker of engraftment in most cases. Long-term engraftment appeared complete for all patients studied with respect to the three methods.