Ultrastructural histochemical evaluation of the surface of normal human blood and bone marrow cells exposed to the
pyroantimonate-osmium (PAO) reaction indicated the selective binding of
pyroantimonate to certain
cations (
calcium,
magnesium, and possibly
sodium) associated with the plasma membrane of neutrophilic leukocytes and their developmental forms. Other leukocytes and their precursors did not exhibit plasma membrane PAO reactivity. The extent of surface binding was related to cell maturity, with maximal labeling evident in the mid and late promyelocytes; decreased binding occurred with subsequent maturation while myeloblasts were nonreactive. This study was initiated to ascertain if histochemical surface modifications of neutrophilic cells occur in certain
myeloproliferative disorders. In this regard, we have been able to demonstrate a distinctive defect in the plasma membrane PAO binding characteristics of the leukemic cells in
chronic myelocytic leukemia (CML). Limited binding of
pyroantimonate to the plasma membrane of the leukemic cell series in four patients with CML contrasted with that of the normal granulocytic cell series and the neutrophilic cells seen in myelomonocytic
leukemia (two patients),
myelofibrosis (one patient), and
acute myelocytic leukemia (three patients). Comparison of surface PAO reactivity of neutrophilic cells in all stages of maturation in two patients with CML in
blast crisis revealed that, in the patient with 30% circulating blast cells, PAO reactivity was identical to that noted in CML, while in the patient with 80% circulating blast forms, the PAO reactivity of the maturing neutrophilic cells more nearly resembled that observed in neutrophilic cells from normal individuals. Many neutrophilic cells from patients with
myelofibrosis and myelomonocytic
leukemia and from one patient in severe
blast crisis had large surface deposits of
pyroantimonate considered to reflect increased membrane-associated reactive
cation.