All issues > Volume 40(12); 1997

Original Article

J Korean Pediatr Soc. 1997;40(12):1660-1669. Published online December 15, 1997.

The Espression of Fcγ Receptors and Mac-1 in Cord and Adult Blood Monocytes and Lymphocytes and Production of Interleukin-8 by Cord and Adult Blood Mononeuclear Cells Stimulated by Lipopolysacchride

Kyung Hyo KH Kim¹, Gyoung Hee GH Kim¹

¹Department of Pediatrics College of Medicine, Ewha Woman`s University, Seoul, Korea

Abstract

Purpose
: The immature neonatal immune system is thought to result in increased risk of infection. Receptors for the Fcmoiety of IgG(FcγR) are important in antibodymediated clearance of microbes by monocytes/macrophages and immune regulation in lymphocytes. As an approach to understanding their role in neonatal life, we have compared the constitutive expression of the three Fc receptors-FcγRI(CD64), FcγRII(CD32) and FcγRIII(CD16)-by neonatal and adult blood monocytes and lymphocytes. Cells of monocyte lineage produce substances chemotactic for neutrophils, including interleukin-8 (IL-8). Neonatal monocytes have diminished function compared with adult cells. This study was designed as an in vitro evaluation of the hypothesis that LPS would induce IL-8 from monocytes and that neonatal production of this molecule would be impaired.
Methods
: Using quantitative immunofluorescence by flow cytometry, we have compared the constitutive expression of the three Fc receptors-FcγRI(CD64), FcγRII (CD32) and FcγRIII(CD16)- and Mac-1(CD11b/CD18) by neonatal and adult blood monocytes and lymphocytes. The levels of IL-8 released from mononuclear cells after LPS stimulation from adult and cord blood were checked with sandwich ELISA method and compared.
Results
: The proportions of FcγRI, FcγRII, and Mac-1 positive monocytes were significanly low in cord blood compared to those of adult. However, in lymphocytes, the expression of those molecules were not different between cord blood and adult. Adult mononuclear cell supernatants contained significantly more IL-8 than did neonatal supernatants in response to LPS.
Conclusion
: There were differences in the expression of Fcγ receptors on monocytes between cord blood and adult peripheral blood and the effects of LPS on the release of IL-8 from mononuclear cells were different in adult and cord. This results suggest that the differences in Fcγ receptor expression may be contributed to the differences in functional activity and decreased production of IL-8 may contribute to the neonate' s poor host response to infection.

Keywords :Fcγ receptor, Mac-1, IL-8, Cord blood