The Expressions of Co-Stimulatory Molecules are Altered on Putative Antigen-Presenting Cells in Cord Blood Dorota Darmochwal-Kolarz 1 , Andrzej Serafin 2 , Jacek Tabarkiewicz 2 , Bogdan Kolarz 2 , Jacek Rolinski 2 , Jan Oleszczuk 1 1 Department of Obstetrics and Perinatology, Medical University of Lublin, Lublin, Poland; 2 Department of Clinical Immunology, Medical University of Lublin, Lublin, Poland Keywords B CD19 + lymphocytes, B7-H1, B7-H4, CD200, CD200R, CD14 + cells, cord blood, dendritic cells Correspondence Dorota Darmochwal-Kolarz, Department of Obstetrics and Perinatology, Medical University of Lublin, ul. Jaczewskiego 8, 20- 950 Lublin, Poland. E-mail: dorotak@mp.pl Submission April 17, 2012; accepted September 17, 2012. Citation Darmochwal-Kolarz D, Serafin A, Tabarkiewicz J, Kolarz B, Rolinski J, Oleszczuk J. The expressions of co-stimulatory molecules are altered on putative antigen-presenting cells in cord blood. Am J Reprod Immunol 2013; 69: 180–187 doi:10.1111/aji.12031 Problem The aim of our study was to estimate the expressions of both B7-H1 and B7-H4 as well as CD200 and CD200R co-stimulatory molecules on immature myeloid and lymphoid dendritic cells, B CD19 + lymphocytes and monocytes in umbilical cord blood of healthy neonates and in peripheral blood of healthy adults. Method of study Thirty-nine healthy full-term neonates from physiological single preg- nancies and 27 healthy adults were included in the study. The expres- sions of B7-H1, B7-H4, CD200, CD200R antigens were estimated using flow cytometry. Statistical analysis was performed using a non-paramet- ric Mann–Whitney U-test and parametric Wilcoxon’s test. Results The expressions of B7-H1 and B7-H4 molecules on immature BDCA-1 + myeloid dendritic cells were significantly lower in umbilical cord blood of healthy neonates when compared with those cells in peripheral blood of healthy adults (P < 0.0001). Furthermore, the suppression of B7-H4 molecule on BDCA-2 + lymphoid dendritic cells was observed in cord blood of healthy neonates when compared with peripheral blood of healthy adults (P < 0.02). The expressions of CD200 antigen on BDCA- 1 + cells, CD200R antigen on BDCA-2 + cells and CD200R antigen on B CD19 + cells were significantly lower in cord blood of healthy neonates. On the other hand, the expressions of CD200 and CD200R as well as B7-H4 co-stimulatory molecules on CD14 + cells were significantly higher in cord blood when compared with peripheral blood. Conclusion The increased percentages of CD14 + monocytes with the expressions of CD200 and CD200R as well as B7-H4 co-stimulatory molecules can sug- gest the increased immunomodulatory properties of neonatal monocytes in cord blood. Introduction There are quantitative and functional differences between the developing fetal and neonatal immune system and the immune system of the adults. The differences concern the innate as well as the adaptive immune responses. For example, the defi- ciencies in the innate immune system of neonates consist in a decreased number and function of neu- trophils and NK cells, a decreased production of American Journal of Reproductive Immunology 69 (2013) 180–187 180 ª 2012 John Wiley & Sons A/S ORIGINAL ARTICLE