Interleukin-3, GM-CSF, and G-CSF receptor expression on cell lines and primary leukemia cells: receptor heterogeneity and relationship to growth factor responsiveness

Recombinant human granulocyte-macrophage (GM) colony-stimulating factor (GM-CSF), G-CSF, and interleukin-3 (IL-3) labeled with 125I were used to study the characteristics and distribution of receptors for these factors on in vitro cell lines and on cells from patients with acute nonlymphocytic leukemia (ANL) and acute lymphocytic leukemia (ALL). Receptors for GM-CSF and G-CSF were restricted to a subset of myelomonocytic cell lines whereas IL-3 receptors were also found on pre- B- or early B-cell lines. Receptors for all three CSFs were broadly distributed on ANL cells, with considerable variability in levels of expression. Measurement of the colony-forming ability of ANL cells in response to the CSFs showed that there was no direct correlation between the ability of the cells to respond to a growth factor and the absolute number of receptors expressed for that growth factor. Binding of radiolabeled IL-3 and GM-CSF to ANL cells produced complex biphasic curves. Further analysis showed that both IL-3 and GM-CSF were able to partially compete for specific binding of the heterologous radiolabeled ligand to cells from several ANL patients, suggesting that heterogeneity may exist in human CSF receptors. These results provide new insights into the complex role that CSFs may play in ANL.     

Age-related changes in proliferative markers in labial salivary glands: a study of argyrophilic nucleolar organizer regions (AgNORs) and Ki-67

The aim of the present study was to examine age-related changes in the proliferative capacity of acinar and ductal cells in labial salivary glands of healthy subjects as reflected by AgNOR and Ki-67 parameters. The study was conducted on 24 postmortem samples of labial salivary glands free from salivary gland tumors/diseases. Samples were equally divided into three age groups: young (mean age 17 yr), adult (mean age 38 yr) and old (mean age 84 yr). The number of profiles of AgNOR (nNOR) and AgNOR profile area per nucleus (TVNOR) were histomorphometrically assessed by CUE-3 automatic image analyzer on 30 nuclei of acinar and intercalated ductal cells in each age group. The percentage of Ki-67 positively stained acinar and ductal cells was evaluated histomorphometrically. Statistical analysis was carried out by one-way ANOVA and Kruskal-Wallis tests. In the acinar cells, nNOR increased significantly with aging (p<0.00001), while TVNOR did not change significantly. In the ductal cells, both nNOR and TVNOR increased significantly (p<0.00001) with a relatively higher increase in TVNOR. Since only isolated acinar and ductal cells demonstrating Ki-67 positive nuclei were found in the different age groups, the overall proliferation index was estimated to be 0%. Thus, it is suggested that age-related changes in AgNOR parameters could reflect changes in the metabolic cell activity rather than changes in their proliferative capacity. In this context, AgNOR results are in accordance with the histomorphometric and physiologic age-related changes occurring in labial salivary glands.     

Coordinate glycosylation and cell surface expression of glycophorin A during normal human erythropoiesis

The expression of two epitopes on glycophorin A (GPA) during erythroid development was examined on normal human bone marrow using quantitative flow cytometry. The highly correlated binding of two monoclonal antibodies, one sensitive and the other insensitive to glycosylation, indicated that the two epitopes were coordinately expressed during erythroid development. Both antigens reached a maximum expression during the early normoblast stage and were maintained at a constant amount per cell throughout further maturation to erythrocytes. These data suggest that glycosylation of GPA, as detected by antibodies recognizing blood group (M) and (N) antigens, does not increase during erythroid maturation.     

Rapid engraftment by peripheral blood progenitor cells mobilized by recombinant human stem cell factor and recombinant human granulocyte colony-stimulating factor in nonhuman primates

We have previously shown that administration of low-dose recombinant human stem cell factor (rhSCF) plus recombinant human granulocyte colony-stimulating factor (rhG-CSF) to baboons mobilizes greater numbers of progenitor cells in the blood than does administration of rhG-CSF alone. The purpose of the present study was to determine whether marrow repopulating cells are present in the blood of nonhuman primates administered low-dose rhSCF plus rhG-CSF, and if present, whether these cells engraft lethally irradiated recipients as rapidly as blood cells mobilized by treatment with rhG-CSF alone. One group of baboons was administered low-dose rhSCF (25 micrograms/kg/d) plus rhG- CSF (100 micrograms/kg/d) while a second group received rhG-CSF alone (100 micrograms/kg/d). Each animal underwent a single 2-hour leukapheresis occurring the day when the number of progenitor cells per volume of blood was maximal. For baboons administered low-dose rhSCF plus rhG-CSF, the leukapheresis products contained 1.8-fold more mononuclear cells and 14.0-fold more progenitor cells compared to the leukapheresis products from animals treated with rhG-CSF alone. All animals successfully engrafted after transplantation of cryopreserved autologous blood cells. In animals transplanted with low-dose rhSCF plus rhG-CSF mobilized blood cells, we observed a time to a platelet count of > 20,000 was 8 days +/- 0, to a white blood cell count (WBC) of > 1,000 was 11 +/- 1 days, and to an absolute neutrophil count (ANC) of > 500 was 12 +/- 1 days. These results compared with 42 +/- 12, 16 +/- 1, and 24 +/- 4 days to achieve platelets > 20,000, WBC > 1,000, and ANC > 500, respectively, for baboons transplanted with rhG-CSF mobilized blood cells. Animals transplanted with low-dose rhSCF plus rhG-CSF mobilized blood cells had blood counts equivalent to pretransplant values within 3 weeks after transplant. The results suggest that the combination of low-dose rhSCF plus rhG-CSF mobilizes greater numbers of progenitor cells that can be collected by leukapheresis than does rhG-CSF alone, that blood cells mobilized by low-dose rhSCF plus rhG-CSF contain marrow repopulating cells, and finally that using a single 2-hour leukapheresis to collect cells, the blood cells mobilized by low-dose rhSCF plus rhG-CSF engraft lethally irradiated recipients more rapidly than do blood cells mobilized by rhG- CSF alone.     

Durability of responses to interferon alfa-2b in advanced hairy cell leukemia

Previous studies have demonstrated that significant hematologic improvement occurs in the majority of patients with hairy cell leukemia (HCL) treated with partially purified or recombinant interferon (IFN). Fifty-three patients received IFN alfa-2b for at least 3 months in a dose of 2 X 10(6) U/m2 subcutaneously thrice weekly. Of the 49 patients evaluable for response (at least 6 months of IFN therapy), there were ten complete responses and 29 partial responses for a total response rate of 80%. The peripheral blood counts and bone marrow continued to improve over the course of a full year of therapy. IFN was well tolerated, with no patients discontinuing therapy because of toxicity. Transient myelosuppression occurred in most patients during the first 1 to 2 months of therapy, occasionally precipitating a transfusion requirement. After IFN treatment was discontinued, there was a marked decrease in normal marrow elements and a relative increase in marrow hairy cells. This was associated with a transient increase in normal elements in the peripheral blood. Only one of 24 patients followed after receiving IFN for a median of 8.5 months (range, 3 to 16 months) has required further therapy. We conclude that low-dose IFN alfa-2b is highly effective in advanced HCL; responding patients should be treated for at least 1 year. The decision to initiate a second course of IFN therapy should be based primarily on peripheral blood counts and the clinical status of the patient rather than on the bone marrow.