ENDOCYTOSIS AND MHC CLASS-II EXPRESSION BY HUMAN OVIDUCTAL EPITHELIUMACCORDING TO STAGE OF THE MENSTRUAL-CYCLE

The epithelium is the first barrier against pathogens invading the lum en of the human oviduct, Its expression of class II major histocompati bility complex (MHC class II) proteins suggests that it might play a r ole in antigen presentation during the local immune response. To study the role of the oviductal epithelium in antigen processing, its endoc ytic properties and MHC class II expression were examined. For assay o f endocytosis, fluorescein isothiocyanate-labelled bovine serum albumi n (BSA-FITC) or Escherichia coli (E. coli-FITC) was infused into the l umen. One-centimetre pieces of oviduct were incubated for 2 h and proc essed for fluorescence and confocal microscopy, and transmission elect ron microscopy, Incorporation into secretory and ciliated epithelial c ells was observed, which was unrelated to the phase of the menstrual c ycle. Small pieces of the organs were frozen and processed for immunoh istochemistry, Most oviducts expressed MHC class II (HLA.DR) in the ep ithelium and in some cases this was coincident with endocytosis, but t here was no statistically significant association between this express ion and either endocytotic activity or the phase of the menstrual cycl e. Results demonstrate that the epithelium of the human oviduct exhibi ts endocytic properties towards luminal soluble and particle antigens, which is not related either to MHC class LI expression or to the phas e of the menstrual cycle.