ABSTRACT
The aim of this study was to detect the expression and cell cycle specificity of Fas, TNFRI and TNFRII in human peripheral blood lymphocytes (PBL), and to study the potential role of Fas, TNFRIand TNFRII in cell cycle specific apoptosis. The improved double-parameter flow cytometry was used to detect the expressions of Fas, TNFRI and TNFRII and cell cycle specificity in PBL which were incubated for 24 hours in the presence or absence of phytohaematoagglutinin (PHA) respectively. Apoptosis induced by IgM type anti-Fas and TNF-alpha was detected by API method. The results showed that compared with PBL treated in the absence of PHA in G(0) phase, the ratio of Fas, TNFRI and TNFRII expressions in PHA-stimulated PBL entering cell cycle increased (35.55 +/- 6.63)%, (30.63 +/- 2.66)%, (26.62 +/- 5.14)% respectively (P < 0.01), and mainly appeared at G(1)-phase; no apoptosis was induced by anti-Fas and TNF-alpha in G(0)-phase PBL cultured in the absence of PHA. On the contrary, the apoptosis was induced by anti-Fas and TNF-alpha in PBL which entered cell cycle after stimulation with PHA and mainly initiated at G(1)-Phase. It is concluded that there is evident dose-effect relationship between apoptotic receptor and receptor-mediated apoptosis. Moreover, the cell cycle specificity of receptor-mediated apoptosis is correlated with the cell cycle specific expressions of apoptotic receptor. The induction of apoptosis by apoptotic factors (anti-Fas and TNF-alpha) depends on whether cell entering cell cycle or not.