EXPRESSION OF DECAY-ACCELERATING FACTOR AND CD59 IN LYMPHOCYTE SUBSETS OF HEALTHY-INDIVIDUALS AND PAROXYSMAL-NOCTURNAL HEMOGLOBINURIA PATIENTS

The expression of phosphatidylinositol (PI)-anchored complement-regula tory membrane proteins on circulating blood cells has been well clarif ied; however, the PI proteins on lymphocyte subsets have not been full y analyzed yet. We examined the expression of decay-accelerating facto r (DAF) and CD59 on the T lymphocytes (CD2+, CD3+, CD4+, and CD8+) and CD20+ B lymphocytes in ten healthy volunteers and 12 paroxysmal noctu rnal hemoglobinuria (PNH) patients by cytofluorometry. In healthy cont rols, each subset of lymphocytes showed a small population of cells we akly positive and a large population of cells strongly positive for DA F and CD59, while erythrocytes showed a single population of cells pos itive for the PI proteins. The two-population expression of DAF was mo st distinctive in CD8 T cells among the subsets. In PNH, each subset o f lymphocytes showed a moderately higher population of cells weakly po sitive and a smaller population of cells strongly positive for the mem brane 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 v alue in PNH patients who receive blood transfusion after hemolytic att ack of affected erythrocytes. Furthermore, the two-population expressi on of PI proteins in normal lymphocytes suggests that membrane PI prot ein would be a new subset marker of lymphocytes.