Neonatal lymphocytes dominate against lymphocytes of their own mother but not against allogenic maternal or adult lymphocytes in bidirectional mixed lymphocyte cultures.
OBJECTIVE
Recent studies have shown a regular prenatal transfer of maternal immunocompetent cells into the fetal circulation. However, these cells engraft and proliferate only in a few exceptional cases if the fetus reaches an immunocompetent state. Thus the fetus has to have an immunologic defense mechanism against the engraftment of maternal cells. In the current study we investigated whether the fetus has such an immune defense and whether this defense mechanism specifically attacks cells of the mother.


METHODS
Blood samples were obtained from 15 mothers and 15 newborns directly after delivery. We compared individual vitality and spontaneous cytotoxicity between fetal and maternal lymphocytes in a cell ratio of 1:1 in nonstimulated bidirectional mixed lymphocyte cultures (MLC). The distribution of each cell population within the MLC was visualized by fluorescence in situ hybridization and X/Y-DNA probes. This was compared to MLCs between unrelated fetal and maternal as well as between unrelated adult lymphocytes.


RESULTS
After 72 h, a significant cell shift was observed only in the MLC with neonatal lymphocytes mixed with cells of their own mother; there was a significantly higher number of neonatal cells (0.71 vs. 0.29) present. All other groups continued to have a cell distribution of 1:1.


CONCLUSIONS
Our results show that neonatal lymphocytes specifically dominate against maternal but not allogenous maternal or adult lymphocytes in nonstimulated bidirectional MLCs.
Brune
Thomas
T
Department of Pediatrics, Otto von Guericke University, Magdeburg, Germany. thbrune@muenster.de
Beier
Kirsten
K
Exeler
Rita
R
Harms
Erik
E
Louwen
Frank
F
D000328:Adult; D041321:Chromosomes, Human, X / Q000235:genetics; D041322:Chromosomes, Human, Y / Q000235:genetics; D003602:Cytotoxicity, Immunologic; D005260:Female; D005312:Fetal Blood / Q000166:cytology / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular; D017404:In Situ Hybridization, Fluorescence; D066298:In Vitro Techniques; D007231:Infant, Newborn; D007519:Isoantigens; D007959:Lymphocyte Culture Test, Mixed; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D008431:Maternal-Fetal Exchange / Q000276:immunology*; D010920:Placenta / Q000276:immunology; D011247:Pregnancy
D007519:Isoantigens