The neutrophil-specific antigen NB1 is expressed by neutrophils from 97% of healthy adults. However, membrane expression of this molecule is unique in that it is found on only a subpopulation of neutrophils present in NB1-positive adults. We have investigated the ontogeny of NB1 antigen expression by haematopoietic progenitor cells to determine the stage and pattern of antigen expression during granulocytic cell differentiation. In addition, we examined whether the ontogeny and frequency of granulocytic cells expressing the NB1 antigen might vary in subjects according to age. A monoclonal antibody (MoAb) specific for NB1 (1B5) and flow cytometry was used to assess the frequency and characteristics of the NB1-positive cells found in umbilical cord blood (n = 11), children (n = 37), healthy adults (n = 46) and patients with chronic myelogenous leukaemia (n = 8). We also used flow cytometry to isolate NB1-positive and NB1-negative bone marrow and peripheral blood cells from various tissue sources. The separated subpopulations were then analysed by Wright stain and light microscopy. The size of the NB1-positive neutrophil subpopulation in 46 healthy adults (56 +/- 19%) was identical to that found for neutrophils from 36 children ranging in age from 8 months to 18 years (56 +/- 11%). In contrast, expression of the NB1 antigen by the neutrophils present in umbilical cord blood (91 +/- 3%, n = 11) was significantly greater than that in adults (P < 0.002) or children (P < 0.002). We also examined the size of the NB1-positive subpopulation among neutrophils from eight patients with chronic myelogenous leukaemia (CML). The NB1-positive subset in CML subjects (29.5 +/- 22.4%) was significantly less that in healthy adults (P < 0.02) or children (P < 0.02). Marrow cells from eight adults were similarly separated and analysed. We found that 69 +/- 17% of segmented and band forms of neutrophils, 70 +/- 2% of metamyelocytes and 61 +/- 23% of myelocytes were NB1-positive. In fetal bone marrow, 86 +/- 9% of the segmented and band forms, 82 +/- 10% of the metamyelocytes and 3 +/- 4% of myelocytes were NB1-positive. In conclusion, neutrophil-specific antigen NB1 is first expressed at the myelocyte stage of myeloid differentiation. In adult bone marrow, the percentages of myelocytes, metamyelocytes and segmented or band cells that expressed this antigen were similar and comparable in magnitude to the frequency of NB1-positive neutrophils found in the circulation. Although the size of the NB1-positive neutrophil subpopulation was the same in healthy adults and children, it was significantly increased in umbilical cord blood, and in fetal marrow cells.

When peripheral blood stem cell (PBSC) concentrates are used for allogeneic transplants, two or more apheresis procedures must often be performed. To determine how many cells could be collected from healthy people by two back-to-back apheresis procedures and what effect these collections would have on donors, we gave 19 healthy people 5 micrograms kg-1 day-1 and 21 people 10 micrograms kg-1 day-1 of granulocyte colony stimulating factor, filgrastim, for 5 days. We then collected two PBSC concentrates, one on day 5 and one on day 6. A third group of six people was given filgrastim 10 micrograms kg-1 day-1 for 5 days but had no PBSC concentrates collected. PBSC concentrate cell counts and donor cell counts, symptoms, and blood chemistries were assessed for up to 1 year. On day 5, three times more CD34+ cells were collected from donors given 10 micrograms kg-1 day-1 than those given 5 micrograms kg-1 day-1 (P = 0.009) but on day 6 the quantity of cells collected was the same (P = 0.23). The total number of CD34+ cells collected was two times greater in donors given the higher dose of filgrastim (median = 579 x 10(6); range = 174-1639 x 10(6) compared to 237 x 10(6); 103-1670 x 10(6); P = 0.061). Platelet counts fell after each PBSC concentrate collection, but there were no differences between the two groups of donors in platelet counts measured immediately after each collection. The platelet counts also fell in people who did not donate PBSC concentrates. The lowest counts in all three groups of people also occurred on day 10. In PBSC donors given 10 micrograms kg-1 day-1 of filgrastim the absolute neutrophil count (ANC) fell below premobilization counts on day 14. In donors given 5 micrograms kg-1 day-1 the ANC fell below premobilization counts on days 21, 28 and 49, CD34+ cell counts were significantly lower than premobilization counts on days 14 and 28 in donors given 10 micrograms kg-1 day-1 of filgrastim and on day 14 in those given 5 micrograms kg-1 day-1. No decrease in neutrophil or CD34+ cell counts occurred after filgrastim was given in the people who did not donate PBSC concentrates. The incidence of symptoms was similar in both groups of PBSC concentrate donors, except that those given 10 micrograms kg-1 day-1 were more than twice as likely to experience myalgias as those receiving the lower dose (P = 0.029). Several blood chemistries changed. Levels of alkaline phosphatase, LDH, SGPT, SGOT, uric acid and sodium increased. Levels of bilirubin, total protein, potassium, calcium and chloride decreased. In conclusion, twice as many CD34+ cells were collected from donors given 10 micrograms kg-1 day-1 of filgrastim. Platelet, neutrophil and CD34+ cell counts fell after the PBSC concentrate collections. The fall in platelet counts was due to both the collection and the administration of filgrastim. The falls in neutrophil and CD34+ cell counts were due to the loss of haematopoietic progenitor cells in the PBSC concentrates. Allogeneic PBSC concentrate donors should be given 10 micrograms kg-1 day-1 of filgras...