Oligoclonal Immunoglobulin Gene Rearrangements in Philadelphia Chromosome‐positive Common Acute Lymphoblastic Leukemia

The occurrence of more than two rearranged bands of immunoglobulin heavy chain (IgH) genes in B precursor acute lymphoblastic leukemia (ALL) has recently been documented. To elucidate the nature of such leukemias, we studied 30 patients with common ALL, including 6 patients with Philadelphia chromosome (Ph(1))‐positive ALL, by immunophenotyping and genotyping. In 10 of the 30, Southern blotting showed oligoclonal patterns of IgH gene arrangements, which were frequently detected in Ph(1)‐positive ALL. In one patient of the 10, three rearranged bands of Ig k chain genes were detected. Ph(1) abnormality and co‐expression of myeloid associated antigens were found in 5 and 5 of the 10, respectively. Detection of multiple fragments of IgH genes would be suggestive of multipotent progenitor origin of these ALL.