Effects of labour and medication on major lymphocyte subsets in cord

It is envisaged that flow cytometric analysis of lymphocyte subsets in cord blood may be used as a biomarker for effects on the immune system of exposure to environmental factors. In order to investigate the possible application of this parameter, we first studied the effects of other factors that may influence the outcome of subset analysis in cord blood. FACS analysis was performed in 112 pairs of umbilical cord blood and of peripheral maternal blood sampled at labour. Whereas in maternal blood no statistically significant effects of medication during labour on T lymphocyte numbers and NK cells were found, in oxytocin- and in oxytocin and prostaglandin-treated mothers B cell numbers showed a statistically significant increase. In cord blood, the course of labour and/or medication during labour were identified as the most important factors determining distribution of major lymphocyte subsets. In cord blood after deliveries without medication or after neuroplegic analgesia (NPA), the mean percentage of cord blood T lymphocytes (CD3 + ) was highest (59%) and that of NK lymphocytes (CD3 ± /CD16 + 56 + ) lowest (20%). The mean percentage of T lymphocytes was significantly lower (52%) and that of NK lymphocytes higher (28%) in cord blood where deliveries were done under NPA in combination with infusion of oxytocin. The combination of NPA with oxytocin and induction of labour by prostaglandin E2 led to a further reduction of T lymphocytes and an increase of NK cells (39% and 38% respectively). The changes in ratio of T and NK lymphocytes were due both to decreasing absolute counts of T lymphocytes and increasing counts of NK lymphocytes. Thus, the effects of labour and/or medication during labour must be taken into account when this parameter is applied as a potential biomarker of effects of environmental factors on the immune system.