ACUTE MYELOID-LEUKEMIA (AML) CAN BE OLIGOCLONAL

Acute myeloid leukemia (AML) is usually thought to represent a monoclo nal disease. Among 45 cases of newly diagnosed AML we found rearranged bands in 14 cases using the Southern blot methodology and immunoglobu lin (Ig) joining region (J(H)) or T-cell receptor (TCR beta) probes. I n three patients, the findings indicated an oligoclonal disease. One c ase was characterized by several bands in the J(H), blot, some of whic h reappeared at different time points during remission. A second case had monoclonally rearranged Ig-J(H) sequences in the bone marrow but e xclusively germline configuration in DNA from peripheral blood cells d espite the presence of 84% blasts. A third case was characterized by t wo different, Ig-J(H) and c mu gene rearranged cell populations at dia gnosis but relapsed with a germline pattern without reappearance of th e previous clones. These data indicate that AML may differentiate alon g different lineages with predominant appearance of one or the other s ubclone in the course of the disease.