A novel alkaline phosphatase isozyme in 4 patients with acute non-lymphocytic leukemia: its nature, origin and clinical significance.

A novel alkaline phosphatase (AP) isozyme has been observed in the serum of 4 patients suffering from acute non-lymphocytic leukemia (ANLL). It resembled the AP of liver/bone origin in most physico-chemical characteristics, but particular electrophoretic characteristics in agar and starch gel and a distinct molecular weight gave this novel AP isozyme its unique character. Its leukemic origin has been demonstrated by isolation from peripheral blood and bone and bone marrow blasts. The appearance of the novel AP isozyme in the patients' sera appeared to be an ominous sign as, in all four, it shortly preceded death. In patients it may have contributed to the observed resistance towards thioguanine therapy.