Distribution of cellular isoform of prion protein in T lymphocytes and bone marrow, analyzed by wild-type and prion protein gene-deficient mice

In this study, the authors investigated normal cellular prion protein (PrP(C)) expression on murine immune systems using prion protein gene-deficient mouse as negative control. Immunocytes expressing PrP(C) in adult and fetal mice were detected by flow cytometry with the monoclonal antibody against PrP(C), 6H4. Cells from thymus and bone marrow reacted positively with 6H4, while spleen cells, peritoneal cells, peripheral blood leukocytes, and intestinal intraepithelial lymphocytes were nonreactive. In thymus, PrP(C) was observed in CD4(-)CD8(-) double-negative thymocytes. PrP(C+) cells of double-negative thymocytes belonged to the CD3(-) subset, but not to the CD3(+) subset. Triple-negative PrP(C+) thymocytes expressed CD44 or CD25 antigens. Furthermore, PrP(C) was observed in c-kit(+) bone marrow cells. In fetuses, PrP(C+) cells were observed in the liver and thymus at day 16.0 and 15.0 of gestation, respectively. These results demonstrated that PrP(C) is expressed on immature immunocytes.