The Effect of Route of Delivery on Neonatal Natural Killer Cytotoxicity and Antibody-Dependent Cellular Cytotoxicity to Herpes Simplex Virus-Infected Cells

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Abstract
Summary: The ability of human neonatal and adult Ficoll-hypaque purified mononuclear cells to mediate natural killer cytotoxicity (NKC) and antibody-dependent cellular-cytotoxicity (ADCC) against 51Cr labeled herpes simplex virus-infected (HSV-infected) and uninfected cells was evaluated in healthy term infants delivered vaginally or by Cesarean (C)-section without labor, and in healthy adult controls. Cord blood NKC to HSV-infected cells (12.5 ± 7.0) was lower (P < 0.01) than adult controls NKC (29.5 ± 7.0). NKC to HSV-infected cells of babies delivered vaginally (16.6 ± 3.4) was lower (P < 0.05) than adult controls (28.4 ± 4.2). NKC to HSV-infected cells of neonates delivered by C-section without labor (7.6 ± 2.8) was also lower (P < 0.001) than adult controls (30.7 ± 4.0) and lower (P < 0.05) than that of neonates delivered vaginally. Cord blood ADCC (43.1 ± 9.0) was lower (P < 0.05) than ADCC of adult controls (58 ± 10). ADCC of neonates delivered vaginally (50 ± 5.9) was similar to ADCC of adult controls (57.4 ± 6.9). ADCC of neonates delivered by C-section without labor (30.4 ± 7.2) was lower than ADCC of adult (58.5 ± 7.4) and was lower (P < 0.05) than ADCC of neonates delivered vaginally. These findings demonstrate that the method of delivery influences subsequent neonatal leukocyte NKC and ADCC. Further experiments will delineate the cause of these variations, which probably include labor or stress related hormonal changes in the mother or neonate. Speculation: Low natural killer cytotoxicity (NKC) and antibody-dependent cellular-cytotoxicity (ADCC) have been suggested to be associated with serious HSV infections in neonates. Past studies have revealed conflicting data concerning levels of NKC and ADCC in the newborn. The present data may help explain disparities of past studies but raise serious questions regarding the use of cord blood ADCC studies to determine the subsequent immunologic competency of newborn infants. Studies on peripheral blood of newborns must be undertaken before the role of ADCC and NKC can be evaluated.