Systemic lupus erythematosus is a complex, multi-organ autoimmune disease . The presence of autoantibodies and circulating immune complexes can cause vasculitis and damage the endothelial cells, leading to multiple organ dysfunctions .The clinical manifestations of SLE include muco cutaneous, musculoskeletal system, cardiac, neurological, renal, hematologic, and vascular system involvement . Nail fold capillaroscopy (NFC) is a non-invasive easily repeatable technique and the best method for morphological analysis of nutritional capillaries in the nail fold area . Nail fold capillary changes are very common in patients with SLE. the major NFC pattern that has been reported in SLE patients was non-specific sub-types, followed by normal pattern and scleroderma pattern. In (SLE) patients are reported a large spectrum of antibodies, including the anti-ribonucleoproteins (RNP) antibodies These antibodies were linked to several clinical manifestations and prognostic in patients with SLE. Anti-U1-RNP antibodies are involved in both innate and adaptive immune responses during pathogenesis of connective tissue diseases 12. U1-RNP complex is an intra nuclear protein that converts pre-mRNA to mature RNA and constitutes three specific proteins A, C, and 70 kDa. High titer RNP antibodies are detected in MCTD patients and correlated with Clinical disease activity index and the frequent complication of pulmonary artery hypertension in those patients . It also has been found that NFC may detect subclinical microvascular changes in SLE in the presence of anti-U1-RNP antibodies and may facilitate early preventive therapy for major organ vasculopathy .
