Abstract

An in vivo culture system, the agar diffusion chamber technique, has been used to measure the population of colony-forming precursor cells in the bone marrow of patients receiving immunotherapy during acute myeloid leukaemia in remission. The results of these assays indicate that (1) the level of committed granulocytic stem cells usually remains below the range found in normal marrow throughout remission, and (2) the maintenance of adequate cell counts in the blood may be due to increased cell production by these early granulocytic precursor cells. The relevance of these findings to the possible protective effect of immunotherapy against cytotoxic chemotherapy is discussed.