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. 2012 Dec 11;5(2):235–249. doi: 10.1002/emmm.201201846

Figure 5. Platelet MPs display citrullinated autoantigens recognized by IgG from RA SF.

Figure 5

  • A,B The presence of citrullinated epitopes on platelet MPs was determined by hs-FCM using anti-citrulline antibody and its corresponding secondary antibody conjugated to Alexa 647. MPs were confirmed of platelet origin using a PE-conjugated anti-CD41 antibody. (A) The presence of citrullinated antigens on platelet MPs was determined in in vitro platelet MPs (left panel) and MPs from RA SF (right panel). The vertical lines were positioned according to the isotypic controls. Pink: Negative population; blue: Positive population. The % of positive platelet MPs is indicated on graphs. (B) Quantification of the citrulline+ CD41+ MPs in RA and PA SF (n = 8 RA and n = 8 PA *p = 0.0148).
  • C,D The proteins from platelet MPs obtained in vitro left unmodified (−PAD4) or citrullinated (+PAD4) were separated on SDS–PAGE and transferred to membranes. The membranes were incubated in presence of RA (C) or PA (D) SF and the recognition of MP-derived autoantigens by autoantibodies from SF was revealed using HRP-conjugated anti-human IgG. Arrows indicate proteins recognized by IgG from SF uniquely when the MPs were citrullinated. Two RA and PA SF are presented to illustrate the existing variability between patients (n = 12 RA and n = 8 PA).