Background Systemic lupus erythematosus (SLE) persists as a chronic inflammatory autoimmune disease. It is characterized by the production of autoantibodies and immune complexes that affect multiple organs (Seitz, 2010). The etiology of SLE is not known, but aberrant apoptosis and/or insufficient clearance of apoptotic material have been assigned a pivotal role (Fransen, 2010). Dendritic cells (DCs) represent an important component of the immune system connecting the innate and adaptive immune responses (Gerl, 2010). SLE patients have increase in number of the plasmacytoid (pDCs) per peripheral blood mononuclear cells but have low number of myeloid myeloid (mDCs) (Lande and Gilliet, 2010).

Objectives To investigate dendrtic cells (DCs) types, plasmacytoid (pDCs) and myeloid (mDCs) in the peripheral blood of SLE patients and prove a role of a ratio of apoptotic cell/DCs in pathogenesis of SLE

Methods This study included 29 SLE patients, 28 females and 1 male with a mean age of 27.13±7.46, who were classified into two groups, SLE patients in activity (16 patients) and SLE patients in remission (13 patients). They were compared with 20 normal controls. All patients were submitted to full history taking, clinical examination using SLEDAI, routine laboratory investigations by complete blood and urine analysis. Blood samples analysis was done using FACS Caliber. Flow cytometric analysis of DCs types, lineage cells and apoptosis (early and late), calculation of (apoptosis/mDCs) ratios were performed in a unit of South Egypt Cancer Institute.

Results mDCs and activated mDCs percentage are decreased in SLE patients and SLE in activity. Late apoptosis percentage is increased. pDCs and activated pDCs percentage are increased in SLE patients but they are decreased during SLE activity. Mature APCs (including DCs) had increased expression of CD86 but low expression of HLA DR. Percentage of early apoptosis is increased in SLE patients; this may be due to impaired clearance of apoptotic cells due to a decrease in mDCs percentage. Increase of the early apoptosis percentage in SLE in remission may be considered impending factor to activity. Percentage of late apoptosis is increased in SLE patients in activity may be due to decrease in activated mDCs percentage in SLE in activity and impaired phagocytic function of activated mDCs. Early apoptosis/whole mDCs ratio is increased in SLE patients than normal controls. This explains the increase of apoptosis percentage in SLE patients and that may be an important factor in SLE pathogenesis

Conclusions The increase of apoptosis percentage in SLE patients may be an important factor in SLE pathogenesis. A ratio of apoptotic cell/DCs has an important role in pathogenesis of SLE.

1. Dendritic cells in SLE. Seitz HM, Int Rev Immunol 01-APR-2010; 29(2): 184-209.

2. The role of dendritic cells in the pathogenesis of SLE. Fransen JH, Arthritis Res Ther 01-JAN-2010; 12(2): 207.

3. Blood dendritic cells in SLE exhibit altered activation state and chemokine receptor function. Gerl V, Ann Rheum Dis 01-JUL-2010; 69(7): 1370-7.

4. Plasmacytoid dendritic cells: key players in the initiation and regulation of immune responses. Lande and Gilliet, Ann N Y Acad Sci 2010; 1183:89-103.

Disclosure of Interest None Declared