A patient with Philadelphia chromosome (Ph) chronic myelogenous leukemia (CML), in chronic phase, was treated with recombinant γ‐interferon (rγ‐IFN) in a phase I clinical trial. Prior to treatment, analysis of in vitro agar culture parameters indicated hyporesponsiveness of granulocyte‐macrophage colony‐forming cells (CFU‐GM) to inhibition by prostaglandin E and acidic isoferritins and diminished expression of class II major histocompatibility complex (MHC) antigens (HLA‐DR). Treatment was associated with no change in bone marrow cellularity or in the percentage of Ph cells. However, in vitro cultures of bone marrow cells showed a return to normal levels of both expression of CFU‐GM class II antigen and of sensitivity to inhibition by prostaglandin E and acidic isoferritins which predicted and/or confirmed clinical response. Throughout the course of interferon therapy, white blood cell counts (WBC) and the percentage of bone marrow blast cells were maintained at normal levels. Onset of aggressive‐phase disease was associated with increased WBC, an increase in bone marrow blast cells, a secondary chromosomal abnormality, loss of CFU‐GM sensitivity to inhibition by putative negative growth regulators, and markedly diminished MHC class II antigen expression. Following a bone marrow transplant from a matched sibling, all hematologic parameters studied were found to be normal. These findings indicate that treatment with rγ‐IFN can modulate some of the abnormal growth characteristics of CFU‐GM observed in CML.
- MHC class II antigens
- chronic myeloid leukemia (CML)
- in vitro growth response
ASJC Scopus subject areas