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Keywords:

  • DAF;
  • T cell;
  • PNH

Abstract

The expression of phosphatidylinositol (PI)-anchored complement-regulatory membrane proteins on circulating blood cells has been well clarified; however, the PI proteins on lymphocyte subsets have not been fully analyzed yet. We examined the expression of decay-accelerating factor (DAF) and CD59 on the T lymphocytes (CD2, CD3+, CD4, and CD8) and CD20+ B lymphocytes in ten healthy volunteers and 12 paroxysmal nocturnal hemoglobinuria (PNH) patients by cytofluorometry. In healthy controls, each subset of lymphocytes showed a small population of cells weakly positive and a large population of cells strongly positive for DAF and CD59, while erythrocytes showed a single population of cells positive for the PI proteins. The two-population expression of DAF was most distinctive in CD8 T cells among the subsets. In PNH, each subset of lymphocytes showed a moderately higher population of cells weakly positive and a smaller population of cells strongly positive for the membrane proteins compared with those in the healthy controls. Moreover, in some PNH cases, a negative population for the proteins was found in all subsets. Thus the analysis of PI-anchored proteins on lymphocyte subsets (especially CD8 T cells) was considered to be of diagnostic value in PNH patients who receive blood transfusion after hemolytic attack of affected erythrocytes. Furthermore, the two-population expression of PI proteins in normal lymphocytes suggests that membrane PI protein would be a new subset marker of lymphocytes.