Nasal polyps (NP) in Chronic Rhinosinusitis with NP (CRSwNP) contain increased fibrin deposition and auto-antibodies, similar to what is found in the antiphospholipid syndrome, where antiphospholipid antibodies (APA) cause prolongation of the activated partial thrombin time (aPTT) in vitro but hypercoagulability in vivo. We hypothesized that functional APA would be elevated in CRSwNP.
NP from CRSwNP (n=34) and ethmoid tissue (ET) from CRSwNP (n=15), CRS without NP (CRSsNP) (n=15), and control (n=17) patients were analyzed by ELISA for total, anti-dsDNA, and anti-cardiolipin IgG. Antibodies from NP homogenates (n=8), APA-negative normal plasma, and APA-positive lupus plasma were isolated using A/G agarose beads. A modified aPTT using these isolated antibodies added to normal plasma was used to compare APA function between APA-negative and positive plasma with NP.
Anti-cardiolipin IgG was significantly increased (p=0.0002) in NP (449.3 GPLU/mg protein) compared to ET from control (89.9 GPLU/mg protein), CRSsNP (187.9 GPLU/mg protein), and CRSwNP (207.4 GPLU/mg protein), and was strongly correlated with anti-dsDNA IgG levels (r=0.75, p<0.0001, n=65). APA from lupus plasma exhibited a significant dose-dependent increase in modified aPTT times compared to normal plasma. NP-derived antibodies significantly prolonged the modified aPTT times compared to APA-positive and -negative plasma-derived antibodies (37.8 vs. 31.1 vs. 30.0 seconds respectively, p<0.0001). Modified aPTT times were also strongly correlated with anti-cardiolipin IgG levels measured in NP extracts (r=0.79, p=0.03, n=8).
Anti-cardiolipin IgG APA are significantly elevated in NP tissue, and may contribute to the increased fibrin deposition in NP.