Anti-CD3-induced and anti-Fas-induced apoptosis in systemic lupus erythematosus (SLE)

Disturbances in apoptosis or in the clearance of apoptotic material might r esult in increased presentation of autoantigens which could be relevant to the pathogenesis of SLE. Data concerning defects in apoptosis in SLE are co nflicting. To determine whether intrinsic defects in apoptosis induction oc cur in SLE irrespective of disease activity, we examined anti-CD3 and anti- Fas-induced apoptosis in vitro in SLE patients with inactive disease. Isola ted peripheral blood lymphocytes (PBL) from 13 SLE patients and 14 healthy controls were incubated with anti-CD3, and, subsequently, after up-regulati on of membrane Fas following anti-CD3 incubation, with anti-Fas. Expression of Fas and levels of apoptosis as detected by annexin V and propidium iodi de staining were assessed by flow cytometry before and after the respective incubations. Fas expression on freshly isolated lymphocytes of SLE patient s was increased whereas levels of circulating apoptotic cells were comparab le between patients and controls. Stimulation with anti-CD3 resulted in up- regulation of membrane Fas in patients and in controls. In vitro induction of apoptosis by anti-CD3 as well as by anti-Fas occurred both in SLE patien ts and controls, and was higher in SLE patients after incubation with anti- CD3 as well as with anti-Fas. We conclude that Fas expression and in vitro induction of apoptosis are increased in SLE even in the absence of disease activity.