lactoferrin and Polycythemia-Vera

Neutrophil granule subsets and dynamics were studied in 4 patients with polycythemia vera/myelofibrosis and 2 patients with chronic myelogenous leukemia. Alkaline phosphatase, a marker for the membrane of secretory vesicles (the most readily mobilizable pool of intracellular membranes in neutrophils) was highly elevated in the PV/MF patients and significantly reduced in the CML patients. In spite of this, the amount of secretory vesicles was normal as judged by the content of albumin, and of the membrane protein cytochrome b-245 and CD11b, both partially localized in secretory vesicles. Gelatinase granules were present in all patients. The azurophil granules were lighter than normal in both CML patients. SDS-PAGE protein profiles indicated absence of defensins from azurophil granules from 1 CML patient. In addition, a 41-42 kD doublet protein band was absent from 2 PV and 1 CML patient, and reduced in the other CML patient. No difference in mobilization of granules was observed between patient neutrophils and control neutrophils. Also, stimulation with 10(-8) mol/l N-formyl-methionyl-leucyl-phenylalanine induced normal increases in intracellular Ca2+ in patient neutrophils. These results indicate that stimulus-response coupling leading to granule exocytosis is intact in neutrophils from patients with myeloproliferative disorders.

Topics: Aged; Alkaline Phosphatase; Cell Fractionation; Centrifugation, Density Gradient; Cytoplasmic Granules; Endopeptidases; Female; Gelatinases; Humans; Lactoferrin; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Male; Middle Aged; Myeloproliferative Disorders; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Polycythemia Vera; Primary Myelofibrosis; Transcobalamins

We have previously reported that the chemiluminescence (CL) response of neutrophils (PMN) from patients with polycythemia vera (PV) was abnormally low when induced by surface receptor-dependent stimuli, fMLP and leukotriene B4, but normal when elicited by phorbol myristate acetate (PMA). This study documents that this discrepancy of the CL response to fMLP and PMA remained over a wide range of stimuli concentrations, was not due to iron-deficient PV cells and was also observed with the nitroblue tetrazolium assay. Moreover, another surface receptor-dependent agonist, platelet-activating factor, conferred a significantly lower CL response in PV PMN relative to controls. Treatment with alpha interferon or GM-CSF, to increase fMLP receptors, resulted in a similar enhancement of fMLP-induced CL in PV and controls. CL was normal when induced by a number of non-surface receptor-dependent stimuli. Release of lactoferrin in response to fMLP (and PMA) was normal (as was previously reported fMLP-induced chemotaxis and adherence). Thus, this defect is highly specific for oxidative metabolism, and localized to discrete step(s) of the stimulus-response coupling for fMLP, leukotriene B4 and PAF, but conceivably not due to impairment of the dynamic interaction of fMLP with its receptor.

Topics: Aged; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; In Vitro Techniques; Interferon-alpha; Lactoferrin; Luminescent Measurements; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Polycythemia Vera; Reference Values; Respiratory Burst; Tetradecanoylphorbol Acetate