Maternal cigarette smoking and its effect on neonatal lymphocyte subpopulations and replication.

Background: Significant immunomodulatory effects have been described as result of cigarette smoking in adults and pregnant women. However, the effect of cigarette smoking during pregnancy on the lymphocyte subpopulations in newborns has been discussed, controversially.

Methods: In a prospective birth cohort, we analyzed the peripheral lymphocyte subpopulations of smoking (SM) and non-smoking mothers (NSM) and their newborns and the replicative history of neonatal, mostly naive CD4 + CD45RA + T cells by measurements of T-cell-receptor-excision-circles (TRECs), relative telomere lengths (RTL) and the serum cytokine concentrations.

Results: SM had higher lymphocyte counts than NSM. Comparing SM and NSM and SM newborns with NSM newborns, no significant differences in proportions of lymphocyte subpopulations were seen. Regardless of their smoking habits, mothers had significantly lower naive T cells and higher memory and effector T cells than newborns. NSM had significantly lower percentages of CD4 + CD25++ T cells compared to their newborns, which was not significant in SM. There were no differences regarding cytokine concentrations in newborns of SM and NSM. However, NSM had significantly higher Interleukin-7 concentrations than their newborns. Regardless of smoking habits of mothers, newborns had significantly longer telomeres and higher TRECs than their mothers. Newborns of SM had significantly longer telomeres than newborns of NSM.

Conclusions: Apart from higher lymphocyte counts in SM, our results did not reveal differences between lymphocyte subpopulations of SM and NSM and their newborns, respectively. Our finding of significantly longer RTL in newborns of SM may reflect potential harm on lymphocytes, such as cytogenetic damage induced by smoking.