Treatment of aplastic anaemia by antilymphocyte globulin with or without marrow infusion.

Forty-one patients, suffering from severe aplastic anaemia were treated either with ALG alone (27 patients) or ALG followed by infusion of allogeneic bone marrow (14 patients). Eighteen patients (67 per cent) are presently alive after ALG alone at over 100 to over 550 days. Fourteen (52 per cent) showed sustained improvement of haematopoiesis, two are alive without change, one recovered autologous haematopoiesis after cyclophosphamide conditioning and transfusion of HLA identical marrow and one is lost to follow-up. Eight patients (57 per cent) are currently alive after ALG and transfusion of haplotype identical marrow with self-sustaining autologous haematopoiesis at over 200 days to over four and a half years. No lethal complications occurred and none of the bone marrow infusions led to permanent engraftment or graft-versus-host disease. The mechanism of action is not known, but our results support the hypothesis that unspecified autoimmune reactions block the normal outgrowth of haematopoietic precursor cells in a substantial number of patients with aplastic anaemia. This therapeutic approach seems to offer good chances of survival, especially for those patients who do not have an HLA identical sibling. Its value should be further investigated.