Original Paper Biol Neonate 1992;62:379-384
a B. Gattegno Research Institute, b Neonatology Unit, c Department of Surgery A, d Golda Medical Center, c Connective Tissue Research Unit, Hasharon Hospital, Golda Medical Center, Petah-Tiqva, Tel Aviv University Medical School, Israel
KeyWords
Sialic acid Maternal lymphocytes Neonatal lymphocytes Parity Y correlated histocompati bility antigens
Sialic Acid Level in Maternal and Neonatal Lymphocytes and Sera Correlated to Birth Order and Sex of the Neonate
Abstract
Sialic acid (N-acetylneuraminic acid) was determined 1 h after normal term deliveries on peripheral blood lymphocytes from 42 mother-neonate pairs and in 29 maternal and neonatal sera. Results were evaluated according to maternal parity and sex of the neonate. The cases were divided into two groups: primiparae, and secundi- and multiparae. In primiparae the sialic acid level on lymphocytes from male neonates and from their mothers was by 23-30% decreased as compared to female neonatal and maternal cells. In the higher parity group, a significantly increased sialic acid level was found on lym phocytes from male as compared to female neonates, and maternal serum sialic acid concentration, unrelated to the newborns’ sex, was by 17-20% increased as compared to primiparae. The results suggest that with increasing parity higher levels of sialic acid on male neonatal cells may possibly contribute to mask fetal male-specific histocompatibility anti gens. Increased sialic acid levels in maternal sera from secun di- and multiparae suggest its possible contribution to an increased serum blocking effect.
Introduction
Sialic acid (N-acetylneuraminic acid) is supposed to contribute to mask antigenic sites on cells from various tissues, and enzymatic
removal of sialic acid residues from lympho cytes or other tissue cells was reported to increase their immunogenicity [1-4]. Sialic acid groups on immature peripheral T cells were found to block adhesion molecules
Luise Komlos. P hD B. Gattegno Research Institute Hasharon Hospital PO B 121 Petah-Tiqva 49372 (Israel)
© 1992 S. Karger AG. Basel 0006-3126/92/ 0626-03 79$2.75/0
Downloaded by: Vanderbilt University Library 129.59.95.115 - 1/13/2019 7:19:27 PM
L. Komios3 J. Landmannh J. Notmann a F. Dnlitzkyb S. Kyzerc J. Hartd I. Halbrecht3 H. Levinskyc
380
newborn sex-correlated differences in the level of E-rosettc-forming lymphocytes from male as compared to female newborns, and recently we observed newborn sex- and birth order-correlated differences in the immune response of mixed mother-newborn lympho cyte cultures (MMNLC) between male and female neonatal cells [16], In view of the pos sible role of sialic acid in the inhibition of his tocompatibility antigen-mediated immunospecific reactions [4, 17], we considered that it would be of interest to determine in the present study sialic acid concentrations on maternal and neonatal peripheral lympho cytes and sera and to try to evaluate and com pare the results according to neonates’ birth order and sex.
Materials and Methods Heparinized venous blood was collected from 42 healthy neonates and from their mothers 1 h after nor mal term deliveries. The neonates included in this study were all born by vaginal delivery. Gestational age was assessed from the date of the last menstrual period and was confirmed in most cases by ultrasound examination in early pregnancy. The range was from 38 to 42 weeks. Infants small for gestational age were excluded. The birth weight of the infants included in this study ranged from 2.700 to 4.000 g. No intrauter ine infections or congenital abnormalities were ob served. Their Apgar score w'as within the normal range. Nineteen male neonates and their mothers, and 23 female neonates and their mothers w'ere included in this study. In 29 cases maternal and neonatal nonheparinized blood for serum separation was also ob tained. From the heparinized blood, lymphocytes were separated by centrifugation on Hypaque-Ficoll gra dient [18]. After repeated washings in saline, aliquots of counted lymphocytes were prepared for the determi nation of bound sialic acid. Sialic Acid Determination in Lymphocytes Washed lymphocytes (10-15 X 106) in 1 ml dis tilled water were frozen and thawed 3 times before being incubated for hydrolysis at 80 °C for 1 h in the presence of 0.1 Y HCl. The released sialic acid was determined by the thiobarbituric acid method of War-
Komlos/Landmann/Notmann/ Dulitzky/Kyzer/Hart/Halbrecht/
Levinsky
Sialic Acid Level in Lymphocytes
Downloaded by: Vanderbilt University Library 129.59.95.115 - 1/13/2019 7:19:27 PM
which have a regulatory function for antigenpresenting cells [5], In human pregnancy, cho rionic gonadotropin receptors were not de tectable on term placental tissue unless the tis sues were pretreated with neuraminidase, in dicating that term pregnancy placenta con tains human chorionic gonadotropin recep tors masked by sialic acid residues [6], Sialic acid residues seem to be involved also in major histocompatibility complex (MHC) ex pression and a decrease in sialic acid content of class I and II HLA antigens was found to be correlated to an increased binding capacity of anti-MHC antibodies [7], In previous studies [6-10], we have deter mined sialic acid levels on umbilical cord blood lymphocytes in term [8, 10] and pre term [9] deliveries and compared the results to maternal and unrelated control lympho cytes. Significantly increased sialic acid levels and sialyltransferase activity [8, 10] were found after term deliveries on umbilical cord lymphocytes as compared to maternal and adult lymphocytes, and the possibility that sialic acid may contribute to paternal histo compatibility masking of fetal lymphocytes and may protect them from immunologic rec ognition by maternal immunocompetent cells was suggested. MHC has been found to be involved in the expression of male-specific Y-chromosomeassociated histocompatibility antigens, and the strength of cell-mediated immunoreactions stimulated by H-Y antigens in female mice was found to be correlated to specific histocompatibility haplotypes [11, 12], Sexcorrelated differences in cell surface sialic acid content have been reported between Xand Y-chromosome-bearing sperm [ 13] and it was suggested that Y-chromosome-bearing sperm has a decreased cell surface sialic acid content as compared to X-bearing cells. In previous studies [14-16] on immune reactions in mother and newborn we found
Table 1. Comparison of sialic acid levels between neonatal and maternal peripheral lymphocytes
Birth order
Cases compared1 female neonates vs. mothers
p value
male neonates vs. mothers
p value
1 II-VII
11-11 12-12
0.05 NS
4-4 15-15
NS
a B. Gattegno Research Institute, b Neonatology Unit, c Department of Surgery A, d Golda Medical Center, c Connective Tissue Research Unit, Hasharon Hospital, Golda Medical Center, Petah-Tiqva, Tel Aviv University Medical School, Israel
KeyWords
Sialic acid Maternal lymphocytes Neonatal lymphocytes Parity Y correlated histocompati bility antigens
Sialic Acid Level in Maternal and Neonatal Lymphocytes and Sera Correlated to Birth Order and Sex of the Neonate
Abstract
Sialic acid (N-acetylneuraminic acid) was determined 1 h after normal term deliveries on peripheral blood lymphocytes from 42 mother-neonate pairs and in 29 maternal and neonatal sera. Results were evaluated according to maternal parity and sex of the neonate. The cases were divided into two groups: primiparae, and secundi- and multiparae. In primiparae the sialic acid level on lymphocytes from male neonates and from their mothers was by 23-30% decreased as compared to female neonatal and maternal cells. In the higher parity group, a significantly increased sialic acid level was found on lym phocytes from male as compared to female neonates, and maternal serum sialic acid concentration, unrelated to the newborns’ sex, was by 17-20% increased as compared to primiparae. The results suggest that with increasing parity higher levels of sialic acid on male neonatal cells may possibly contribute to mask fetal male-specific histocompatibility anti gens. Increased sialic acid levels in maternal sera from secun di- and multiparae suggest its possible contribution to an increased serum blocking effect.
Introduction
Sialic acid (N-acetylneuraminic acid) is supposed to contribute to mask antigenic sites on cells from various tissues, and enzymatic
removal of sialic acid residues from lympho cytes or other tissue cells was reported to increase their immunogenicity [1-4]. Sialic acid groups on immature peripheral T cells were found to block adhesion molecules
Luise Komlos. P hD B. Gattegno Research Institute Hasharon Hospital PO B 121 Petah-Tiqva 49372 (Israel)
© 1992 S. Karger AG. Basel 0006-3126/92/ 0626-03 79$2.75/0
Downloaded by: Vanderbilt University Library 129.59.95.115 - 1/13/2019 7:19:27 PM
L. Komios3 J. Landmannh J. Notmann a F. Dnlitzkyb S. Kyzerc J. Hartd I. Halbrecht3 H. Levinskyc
380
newborn sex-correlated differences in the level of E-rosettc-forming lymphocytes from male as compared to female newborns, and recently we observed newborn sex- and birth order-correlated differences in the immune response of mixed mother-newborn lympho cyte cultures (MMNLC) between male and female neonatal cells [16], In view of the pos sible role of sialic acid in the inhibition of his tocompatibility antigen-mediated immunospecific reactions [4, 17], we considered that it would be of interest to determine in the present study sialic acid concentrations on maternal and neonatal peripheral lympho cytes and sera and to try to evaluate and com pare the results according to neonates’ birth order and sex.
Materials and Methods Heparinized venous blood was collected from 42 healthy neonates and from their mothers 1 h after nor mal term deliveries. The neonates included in this study were all born by vaginal delivery. Gestational age was assessed from the date of the last menstrual period and was confirmed in most cases by ultrasound examination in early pregnancy. The range was from 38 to 42 weeks. Infants small for gestational age were excluded. The birth weight of the infants included in this study ranged from 2.700 to 4.000 g. No intrauter ine infections or congenital abnormalities were ob served. Their Apgar score w'as within the normal range. Nineteen male neonates and their mothers, and 23 female neonates and their mothers w'ere included in this study. In 29 cases maternal and neonatal nonheparinized blood for serum separation was also ob tained. From the heparinized blood, lymphocytes were separated by centrifugation on Hypaque-Ficoll gra dient [18]. After repeated washings in saline, aliquots of counted lymphocytes were prepared for the determi nation of bound sialic acid. Sialic Acid Determination in Lymphocytes Washed lymphocytes (10-15 X 106) in 1 ml dis tilled water were frozen and thawed 3 times before being incubated for hydrolysis at 80 °C for 1 h in the presence of 0.1 Y HCl. The released sialic acid was determined by the thiobarbituric acid method of War-
Komlos/Landmann/Notmann/ Dulitzky/Kyzer/Hart/Halbrecht/
Levinsky
Sialic Acid Level in Lymphocytes
Downloaded by: Vanderbilt University Library 129.59.95.115 - 1/13/2019 7:19:27 PM
which have a regulatory function for antigenpresenting cells [5], In human pregnancy, cho rionic gonadotropin receptors were not de tectable on term placental tissue unless the tis sues were pretreated with neuraminidase, in dicating that term pregnancy placenta con tains human chorionic gonadotropin recep tors masked by sialic acid residues [6], Sialic acid residues seem to be involved also in major histocompatibility complex (MHC) ex pression and a decrease in sialic acid content of class I and II HLA antigens was found to be correlated to an increased binding capacity of anti-MHC antibodies [7], In previous studies [6-10], we have deter mined sialic acid levels on umbilical cord blood lymphocytes in term [8, 10] and pre term [9] deliveries and compared the results to maternal and unrelated control lympho cytes. Significantly increased sialic acid levels and sialyltransferase activity [8, 10] were found after term deliveries on umbilical cord lymphocytes as compared to maternal and adult lymphocytes, and the possibility that sialic acid may contribute to paternal histo compatibility masking of fetal lymphocytes and may protect them from immunologic rec ognition by maternal immunocompetent cells was suggested. MHC has been found to be involved in the expression of male-specific Y-chromosomeassociated histocompatibility antigens, and the strength of cell-mediated immunoreactions stimulated by H-Y antigens in female mice was found to be correlated to specific histocompatibility haplotypes [11, 12], Sexcorrelated differences in cell surface sialic acid content have been reported between Xand Y-chromosome-bearing sperm [ 13] and it was suggested that Y-chromosome-bearing sperm has a decreased cell surface sialic acid content as compared to X-bearing cells. In previous studies [14-16] on immune reactions in mother and newborn we found
Table 1. Comparison of sialic acid levels between neonatal and maternal peripheral lymphocytes
Birth order
Cases compared1 female neonates vs. mothers
p value
male neonates vs. mothers
p value
1 II-VII
11-11 12-12
0.05 NS
4-4 15-15
NS
