Alkaline Phosphatase Activity in Neutrophils of Chronic Myelocytic Leukemia Grown in Liquid Culture

Abstract

Bone marrow cells from 8 Ph¹-positive patients with chronic myelocytic leukemia (CML) have been cultured in vitro. Cellular growth in the presence of the Ph¹-chromosome and neutrophil alkaline phosphatase (NAP) have been evaluated at intervals of time during 19 days of culture. The mean viable neutrophil count reached a peak level on day 8, and the Ph¹-chromosome was present till day 10 suggesting an active proliferation of leukemic stem cells. NAP activity reached a maximun level in the same number of days as the neutrophil peak.Our data suggest that newly formed neutrophils (Ph¹+) in CML are normal as far as NAP activity is concerned. Moreover, they emphasize the hypothesis that in CML there is an accumulation of aged NAP-negative cells, diluting positive neutrophils with a consequent low NAP score.

Evidence for two isozymes of leukocyte alkaline phosphatase in leukemic leukocytes

“…In patients with chronic granulocytic leukemia (CGL) LAP is decreased or absent by histochemical determination in patients with stable-phase disease, but may become normal or elevated in patients entering blast phase [13][14][15][16][17][18]. Stable-phase CGL cells have repeatedly been shown to have increased levels of LAP after being maintained in tissue culture for several days [19][20][21][22]. The mechanism of this induction of LAP activity is unknown.…”