Cytofluorometric analysis of the neutrophil-specific BH2-Ag on cells from neonates to adults

Monoclonal antibody (MAB) BH2C6 recognizes a plasma membrane antigen, the B H2-Ag, specifically expressed by human neutrophils. While studies with peri pheral blood and bone marrow from healthy adults clearly demonstrate the ab sence of BH2-Ag from other cellular components except neutrophils, they als o indicate that the BH2-Ag is expressed more strongly by mature than immatu re neutrophils. The purpose of this study was to determine the expression o f the BH2-Ag by peripheral blood neutrophils from premature newborns to adu lts. Seventy-two donors were studied in six age groups: newborns <36 weeks of gestational age; newborns >36 weeks of gestational age; 0.5-2 years; 4-8 years; 12-17 years; >30 years. Expression of the BH2-Ag by peripheral bloo d neutrophils was examined by cytofluorography using MAB BH2-C6 directly la beled with fluorescein isothiocyanate (FITC). Neutrophils were reacted in p arallel with FITC-MAB directed against CD11b, the a-chain of the CD11b/CD18 antigen (CR3). BH2-Ag is expressed by 98.3-99.6% of the neutrophils in all groups, and is absent on other blood cells, including those of very premat ure newborns. Statistical comparisons with respect to the mean fluorescence intensity of the FITC-MAB BH2C6 bound did not support a significant differ ence in the expression of BH2-Ag in any age group. CD11b expression was als o detected in every individual studied and its mean fluorescence intensity correlated significantly with that of BH2Ag (p <0.001). The uniform presenc e of BH2Ag in every individual including a very premature infant suggests t hat BH2-Ag is likely to be an essential component of neutrophil development in humans. A highly significant correlation between the mean fluorescence intensify obtained with MAB BH2C6 and MAB CD11b suggests a possible interac tive role of the two antigens in neutrophil development and/or function.