V-Chain Preference of Gamma ⁄ Delta T-Cell Receptors in Peripheral Blood During Term Labor Aliz Barakonyi 1 , Eva Miko 1 , Peter Varga 2 , Julia Szekeres-Bartho 1 1 Department of Medical Microbiology and Immunology, Medical School, Pecs University, Pecs, Hungary; 2 Department of Obstetrics and Gynecology, County Hospital, Pecs, Hungary Introduction Maternal immune responsiveness is altered during pregnancy, to create a favorable environment for the developing fetus. Coming up to term, new regula- tory mechanisms set in, to initiate labor. The transi- tion from the state of uterine quiescence to activation is accompanied by increased expression of oxitocin and endothelin receptors, formation of gap junctions, increased concentration of uterotonic agents 1 and altered cytokine production. 2–4 Increas- ing evidence supports the concept that human parturition represents an inflammatory response. The process of cervical dilatation is associated with augmented expression of interleukin (IL)-1b, IL-6, and IL-8 mRNAs in the lower uterine segment. 5 The concentration of IL-1b and IL-6 increases in cervico- vaginal secretions during spontaneous term labor peaking at the time of complete cervical dilatation. 6,7 Although the level of IL-1a in vaginal 8 or amniotic fluid and in the peripheral blood does not signifi- cantly differ between pregnant women and those in labor, human placental explant cultures from deliv- ery release increased amounts of IL-1a. 9 Tumor Keywords Parturition, pregnancy, T-cell phenotype Correspondence Julia Szekeres-Bartho, Department of Medical Microbiology and Immunology, Medical School, Pecs University, 7624-Pecs, Szigeti u. 12, Hungary. E-mail: julia.szekeres@aok.pte.hu Submitted October 10, 2007; accepted October 30, 2007. Citation Barakonyi A, Miko E, Varga P, Szekeres- Bartho J. V-chain preference of gamma ⁄ delta T-cell receptors in peripheral blood during term labor. Am J Reprod Immunol 2008; 59: 201–205 doi:10.1111/j.1600-0897.2007.00555.x Problem An altered function of the maternal immune system creates a favorable environment for the developing fetus during pregnancy. At term, new regulatory mechanisms are activated, to initiate labor. Earlier we showed that in peripheral blood of pregnant women gamma ⁄ delta T cells of cytotoxic phenotype are replaced by those of a non-cytotoxic phenotype. Here we studied the Vgamma and Vdelta chain usage of peripheral gamma ⁄ delta T cells from women in labor. Method of study Vgamma and Vdelta chain expression on peripheral blood lymphocytes obtained at the 3rd trimester of pregnancy and during parturition were examined by immuncytochemistry and flow cytometry. Results Increased % of Vgamma9 ⁄ Vdelta2 and decreased % of Vgamma4 ⁄ V- delta1 T cells were found in peripheral blood during labor, together with unaltered percentages of single Vgamma+ or Vdelta+ cells. The initially high Vgamma4 ⁄ Vdelta1 to Vgamma9 ⁄ Vdelta2 ratio decreased during labor. Conclusion The initiation of labor is characterized by an altered V-chain usage of gamma ⁄ delta T cells. ORIGINAL ARTICLE American Journal of Reproductive Immunology 59 (2008) 201–205 ª 2008 The Authors Journal compilation ª 2008 Blackwell Munksgaard 201