Expression and localization of the Th2-type cytokine interleukin-13 and its receptor in the placenta during human pregnancy

PROBLEM: To investigate the expression of the Th2-type cytokine interleukin (IL)-13 and its receptor in human placenta during gestation. METHOD OF STUDY: Expression of IL-13 and its receptor was analyzed by reverse transcriptase (RT)-polymerase chain reaction (PCR), in situ hybridization and immunohistochemistry using human placental samples. RESULTS: IL-13 mRNA was detected by RT-PCR in placental extracts from all stages of gestation. In situ hybridization revealed IL-13 mRNA in first trimester cytotrophoblast and syncytiotrophoblast. Few positive cells were found within decidual sections from the same pregnancy. Immunohistochemistry revealed a similar pattern to in situ hybridization. This was largely absent in second- and third-trimester placentae. IL-13 receptor alpha chain (IL-13R alpha) was detected by immunofluorescence on the surface of leukocytes in first-trimester villous core and decidua. CONCLUSIONS: The expression of IL-13 is spatially and temporally regulated in the placenta, and associated with the close proximity of a receptor-bearing target leukocyte population.