Differential expression of cellular prion protein on human blood and tonsil lymphocytes

Background and Objectives. The expression of cellular prion protein (PrPc) on the surface of peripheral lymphocytes has been previously reported, but little is known about its expression on lymphoid cells from secondary lymph organs. In this report, we compare the surface expression of PrPc on human blood lymphocytes and tonsil lymphocytes. Design and Methods. This analysis was performed by cytometry on live lympho cytes isolated from healthy donors or from the tonsils of adults or childre n. Results. Human peripheral lymphocytes and tonsillar lymphoid cells, but not erythrocytes or granulocytes, express PrPc at their surfaces. Interestingl y, we found significantly less PrPc on freshly Isolated tonsil lymphocytes, both B and T, than on blood cells. Although tonsil cells bear less PrPc th an circulating blood lymphocytes, they are able to express high quantities of PrPc on their surface when placed In culture. However, contrary to previ ous results, mitogen stimulation does not affect this expression on B- or T -cells. Interpretation and Conclusions. We suggest that the PrPc expression by lymp hocytes may be modified by interactions occurring during intratissular migr ation or during cell-to-cell contacts. Whether PrPc plays a role in Intrace llular communication at this location, as it does In the nervous system, re mains an open question. (C) 2000, Ferrata Storti Foundation.