Labour increases the surface expression of two toll-like receptors in the cord blood monocytes of healthy term newborns

Aim: Mode of delivery may influence the innate immune system in newborns. We investigated the effect of maternal labour on the expression of two toll-like receptors, TLR2 and TLR4, in monocytes obtained from healthy full-term newborns. Methods: Monocytes were obtained from cord blood of 48 newborns that have been vaginally delivered (VD) and 14 newborns delivered by elective caesarean section (CS) without labour. Peripheral blood was also obtained from 17 healthy adults. Surface expression of TLR2 and TLR4 in the monocytes was measured by antihuman TLR2 or TLR4 monoclonal antibody and immunofluorescence flow cytometry. TLR2 and TLR4 mRNA levels were evaluated by real-time PCR. Results: CS newborns had a significantly lower level of TLR2 and TLR4 surface expression on monocytes than VD newborns. No significant difference was found between the surface expression of VD newborns and healthy adults. TLR2 and TLR4 mRNA levels in monocytes did not vary among the three study groups. Conclusion: Labour may up-regulate TLR2 and TLR4 on the cord blood monocytes of newborns at the protein level. Since TLRs are an important part of the innate immune system, our findings suggest that labour may be immunologically beneficial to normal newborns.