A Study of Receptor Expression in Leukocytes by Quantitative Fluorescence Measurement

PURPOSE: It is well known that the receptors for Fcgamma moiety of IgG(FcgammaR) are instrumental in antibody-mediated clearance of microorganisms by granulocytes and monocytes, and immune regulation in lymphocytes. Furthermore, complement receptor-3(CR3) is also important in neutrophilic adhesion, diapedesis, and phagocytic functions. In an attempt to examine their roles in neonates, we compared the expressions of FcgammaRs and CR3 in cord blood leukocytes with those expressed in leukocytes in samples of blood obtained from adult subjects. METHODS: Cord blood was obtained from 30 full-term newborn and peripheral blood from 30 adult volunteers. In both groups, we measured three Fcgamma receptors and one adhesion molecule, CR3 on granulocytes, monocytes and lymphocytes using a whole blood method with flow cytometry and quantitative bead standards to enumerate the cell surface receptors. RESULTS:Compared to those observed in adult blood, the proportions of FcgammaRI+ granulocytes were significantly higher in cord blood. By contrast, the proportions of FcgammaRII+ or FcgammaRIII+ granulocytes and the number of FcgammaRIII were significantly lower in cord blood. The proportions of FcgammaRI+, FcgammaRII+, and CD18+ bearing monocytes and the number of FcgammaRII in lymphocytes were also significantly lower in cord blood as compared to adult blood. CONCLUSION: There were differences in the proportions of cells expressing FcgammaRs and CR3 and in the number of FcgammaRs and CR3 in granulocytes, monocytes, and lymphocytes between cord blood and peripheral blood from adult subjects. These may contribute to the difference in immune capability that is known to exist between neonates and adult subjects.

Phenotypic and Functional Differentiation of Promyelocytic Cell Line HL-60 by N-N-dimethylformamide

PURPOSE: HL-60 is a promyelocytic cell line. Fc receptors and complement receptor 3 (CR3) play important role in the protective response of granulocytes and monocytes against microbial infection. We quantified the expression of Fc I, Fc II, Fc III, and CD11b/CD18 during differentiation using HL-60 cells by N-N-dimethylformamide (DMF). Functional studies, such as phagocytic activity, respiratory burst and ADCC, were also performed. METHODS: HL-60 cells were induced to differentiate by adding 0.8% DMF. On the 4th and 7th day after stimulation as well as before stimulation, the cells were analyzed for phenotypic and functional differentiaton. Phenotypic analysis was performed by flow cytometry after staining the cells with PE-conjugated anti-human CD64, CD32, CD16, CD11b, CD18, and isotype controls. And the measured fluorescent intensity was transformed into Molecules of Equivalent Soluble Fluorochromes (MESF). Phagocytic activity was also measured by flow cytometry after incubation with fluorochrome-conjugated beads. Respiratory burst was measured by chemiluminescence assay of cells incubated with luminol after stimulation with PMA. ADCC was measured by hemoglobin release assay. RESULTS: The expression of CD11b, CD18 and CD64 on HL-60 cells markedly increased on the 4th day and slightly decreased on the 7th day. Expression of CD32 was already induced before differentiation induction and slightly increased by DMF. CD16 was not expressed during differentiation. In phagocytic assay, the phagocytic cell fraction increased by stimulation on 4th and 7th day. Chemiluminescence showed the DMF increased the respiratory burst of HL-60 cells on the 4th and 7th day. In ADCC, DMF increased the target cell lysis continuously. CONCLUSION: HL-60 cells which were differentiated with DMF for are good models for studying opsonophagocytic assay of immunized sera.