Human autoantibodies to diacyl-phosphatidylethanolamine recognize a specific set of discrete cytoplasmic domains.

The aim of this study was to characterize a novel human autoantibody-autoantigen system represented as cytoplasmic discrete speckles (CDS) in indirect immunofluorescence (IIF). A distinct CDS IIF pattern represented by 3-20 discrete speckles dispersed throughout the cytoplasm was identified among other cytoplasmic speckled IIF patterns. The cytoplasmic domains labelled by human anti-CDS-1 antibodies did not co-localize with endosome/lysosome markers EEA1 and LAMP-2, but showed partial co-localization with glycine-tryptophan bodies (GWB). CDS-1 sera did not react with several cellular extracts in immunoblotting and did not immunoprecipitate recombinant GW182 or EEA1 proteins. The typical CDS-1 IIF labelling pattern was abolished after delipidation of HEp-2 cells. Moreover, CDS-1 sera reacted strongly with a lipid component co-migrating with phosphatidylethanolamine (PE) in high performance thin-layer chromatography (HPTLC)-immunostaining of HEp-2 cell total lipid extracts. The CDS-1 major molecular targets were established by electrospray ionization-mass spectrometry (ESI-MS), HPTLC-immunostaining and chemiluminescent enzyme-linked immunosorbent assay as diacyl-PE species, containing preferentially a cis-C18 : 1 fatty acid chain at C-2 of the glycerol moiety, namely 1,2-cis-C18 : 1-PE and 1-C16 : 0-2-cis-C18 : 1-PE. The clinical association of CDS-1 sera included a variety of systemic and organ-specific autoimmune diseases but they were also observed in patients with no evidence of autoimmune disease.

Antibodies to fibrin-bound tissue-type plasminogen activator in systemic lupus erythematosus are associated with Raynaud's phenomenon and thrombosis.

Fibrinolysis triggered by t-PA bound to fibrin is one of the main antithrombotic mechanisms. Defects in the fibrinolytic system-decreased tissue-type plasminogen activator (t-PA) activity and elevated levels of plasminogen activator inhibitor (PAI-1), in patients with SLE have been associated with an increased tendency to thrombosis. In the present study, 43 patients with SLE fulfilling the ACR criteria for the disease, were studied for the presence of autoantibodies to fibrin-bound t-PA, i.e. the physiological active form of this plasminogen activator. A solution of 200 IU/ml of t-PA was incubated with solid-phase fibrin prepared as previously described (Anal Biochem 1986; 153; 201-210). Sera diluted 1:50 were incubated with fibrin-bound t-PA, the plates were then washed, and bound immunoglobulins were detected using a polyvalent peroxidase-labeled goat anti-human Ig. Plates coated with fibrin alone were used as controls. Sera were considered positive when A490/630 obtained with normal human sera in two independent test was greater than the mean plus 2 SD. Eleven of 43 (26%) SLE sera demonstrated antibody reactivity against fibrin-bound t-PA. Within the anti-t-PA positive group there was a higher proportion of SLE patients with severe Raynaud's phenomenon and thrombotic events when compared to the anti-t-PA negative group: 36% vs 6% and 18% vs 6% respectively. These results suggest that autoantibodies to fibrin-bound t-PA could play a role in the pathogenesis of vascular disease in some SLE patients.

Autoantibodies in Parry-Romberg syndrome: a serologic study of 14 patients.

OBJECTIVE: To determine autoantibody profiles of patients with Parry-Romberg syndrome (PRS). METHODS: Antinuclear antibodies (ANA) in 14 patients with PRS were studied by indirect immunofluorescence (IIF), immunodiffusion and immunoblotting. Antinative DNA antibodies and rheumatoid factor (RF) were also analyzed. RESULTS: ANA were positive in 8 patients (57%). The patterns of staining included nucleolar, nuclear speckled and homogeneous. Anticentromere antibodies were observed in 2 and antihistone antibodies in 3 sera. Rheumatoid factor was found in 5 (36%) sera. Antinative DNA or antibodies that precipitated rabbit thymus extract were not found in any patients. CONCLUSION: The serologic abnormalities observed in this study suggests that autoimmunity could play a pathogenic role in PRS.