Non-leukemic dividing cells in the blood of leukemic patients

Spontaneous mitoses in the blood of 67 patients with acute leukemia were enumerated and their identity determined by cytogenetic methods. Most patients were children with acute lymphoblastic leukemia. Simultaneous 16- to 20-hour cultures of blood leukocytes (Bu) and of bone marrow (BM) cells were performed without phytohemagglutinin (PHA). Blood leukocytes were also cultured with PHA for 72 hours (BPHA). Mitoses in Bu cultures were counted, and karyotypic analysis performed on cells from the three culture types. In 21 control subjects, Bu cultures usually yielded no mitoses. Relapse and remission patients both displayed significantly more Bu mitoses than the controls. The karyotypes of Bu, BPHA, and BM mitoses in remission patients were normal. Fifty percent of relapse patients displayed cytogenetically abnormal leukemia cell lines; the percentage of their abnormal karyotypes was significantly higher in BM cells than in Bu or BPHA cells. The majority of the mitotic cells in Bu cultures from both relapse and remission patients appear to be of a nonleukemic origin. The number of mitoses could not be correlated with type of leukemia, hematologic parameters, or prognosis.