OBJECTIVE: To quantify immunoglobulin and C1q on circulating cell-derived microparticles (MPs) in patients with systemic lupus erythematosus (SLE) and to determine whether immunoglobulin and C1q levels are correlated with clinical and serologic parameters. METHODS: Sixty-eight clinically well-characterized SLE patients, 38 healthy controls, 6 patients with systemic sclerosis (SSc), and 6 patients with rheumatoid arthritis (RA) were included. The numbers of annexin V-binding MPs displaying IgG, IgM, or C1q were enumerated by flow cytometry. MP protein levels were determined by mass spectrometry in clinically defined subsets of SLE patients and controls. The MP IgG load was determined by flow cytometric analysis of all samples from SLE patients and healthy controls. RESULTS: SLE patients had significantly increased total and relative numbers of IgG-positive MPs (P = 0.0004), with a much higher average IgG load per MP (P < 0.0001) than healthy controls. Quantitative mass spectrometry of purified MPs verified significantly increased IgG, IgM, and C1q levels in SLE patients. In RA and SSc patients, the average IgG load per MP was significantly lower than in SLE patients (P = 0.006 and P = 0.05, respectively). Also, the IgM load and C1q load per MP were significantly higher in SLE patients than in the control groups (P < 0.05), except for IgM in the RA group. IgG-positive MPs were significantly associated with the presence of anti-double-stranded DNA, anti-extractable nuclear antigen, and antihistone antibodies, with total IgG, and with decreased leukocyte counts. Average IgG load per MP was associated with lower concentrations of MPs, the presence of anti-C1q antibodies, and complement consumption. CONCLUSION: Our findings indicate that circulating cell-derived MPs in SLE patients carry increased loads of IgG, IgM, and C1q and that IgG MPs are associated with autoantibodies and complement activation. The findings link immunologic reactions on MPs with the etiology of SLE.
OBJECTIVE: To quantify immunoglobulin and C1q on circulating cell-derived microparticles (MPs) in patients with systemic lupus erythematosus (SLE) and to determine whether immunoglobulin and C1q levels are correlated with clinical and serologic parameters. METHODS: Sixty-eight clinically well-characterized SLEpatients, 38 healthy controls, 6 patients with systemic sclerosis (SSc), and 6 patients with rheumatoid arthritis (RA) were included. The numbers of annexin V-binding MPs displaying IgG, IgM, or C1q were enumerated by flow cytometry. MP protein levels were determined by mass spectrometry in clinically defined subsets of SLEpatients and controls. The MP IgG load was determined by flow cytometric analysis of all samples from SLEpatients and healthy controls. RESULTS:SLEpatients had significantly increased total and relative numbers of IgG-positive MPs (P = 0.0004), with a much higher average IgG load per MP (P < 0.0001) than healthy controls. Quantitative mass spectrometry of purified MPs verified significantly increased IgG, IgM, and C1q levels in SLEpatients. In RA and SSc patients, the average IgG load per MP was significantly lower than in SLEpatients (P = 0.006 and P = 0.05, respectively). Also, the IgM load and C1q load per MP were significantly higher in SLEpatients than in the control groups (P < 0.05), except for IgM in the RA group. IgG-positive MPs were significantly associated with the presence of anti-double-stranded DNA, anti-extractable nuclear antigen, and antihistone antibodies, with total IgG, and with decreased leukocyte counts. Average IgG load per MP was associated with lower concentrations of MPs, the presence of anti-C1q antibodies, and complement consumption. CONCLUSION: Our findings indicate that circulating cell-derived MPs in SLEpatients carry increased loads of IgG, IgM, and C1q and that IgG MPs are associated with autoantibodies and complement activation. The findings link immunologic reactions on MPs with the etiology of SLE.
Authors: María Yáñez-Mó; Pia R-M Siljander; Zoraida Andreu; Apolonija Bedina Zavec; Francesc E Borràs; Edit I Buzas; Krisztina Buzas; Enriqueta Casal; Francesco Cappello; Joana Carvalho; Eva Colás; Anabela Cordeiro-da Silva; Stefano Fais; Juan M Falcon-Perez; Irene M Ghobrial; Bernd Giebel; Mario Gimona; Michael Graner; Ihsan Gursel; Mayda Gursel; Niels H H Heegaard; An Hendrix; Peter Kierulf; Katsutoshi Kokubun; Maja Kosanovic; Veronika Kralj-Iglic; Eva-Maria Krämer-Albers; Saara Laitinen; Cecilia Lässer; Thomas Lener; Erzsébet Ligeti; Aija Linē; Georg Lipps; Alicia Llorente; Jan Lötvall; Mateja Manček-Keber; Antonio Marcilla; Maria Mittelbrunn; Irina Nazarenko; Esther N M Nolte-'t Hoen; Tuula A Nyman; Lorraine O'Driscoll; Mireia Olivan; Carla Oliveira; Éva Pállinger; Hernando A Del Portillo; Jaume Reventós; Marina Rigau; Eva Rohde; Marei Sammar; Francisco Sánchez-Madrid; N Santarém; Katharina Schallmoser; Marie Stampe Ostenfeld; Willem Stoorvogel; Roman Stukelj; Susanne G Van der Grein; M Helena Vasconcelos; Marca H M Wauben; Olivier De Wever Journal: J Extracell Vesicles Date: 2015-05-14
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