Relevance of colony forming assays to bone marrow transplanation with particular reference to grafting for aplastic anaemia.

The value of bone marrow colony-forming assays in monitoring transplanted patients has been assessed by comparing results from two pairs of bone marrow recipients. One pair received marrow from their identical twins for acute lymphoblastic leukaemia; the other pair were grafted with allogeneic marrow from their siblings for aplastic anaemia. One of each pair showed successful engraftment while in the others the grafts failed. The colony-forming assay was then used to investigate marrow function in five grafted aplastic patients. Of these, four rejected their first grafts and required further immunosuppression before engraftment could be accomplished. The remaining patient was immunosuppressed at the outset with antithymocyte globulin (ATG) and her first graft was successful. Sera from all five patients inhibited colony formation by normal human marrow and it is suggested that this activity was related to graft rejection as well as to the pathogenesis of the condition.