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6 pages, 4 figures, supporting information https://www.pnas.org/content/115/46/11706/tab-figures-data, Some commonly referenced thermal-mechanical models of current subduction zones imply temperatures that are 100-500 °C colder at 30-80-km depth than pressure-temperature conditions determined thermobarometrically from exhumed metamorphic rocks. Accurately inferring subduction zone thermal structure, whether from models or rocks, is crucial for predicting metamorphic reactions and associated fluid release, subarc melting conditions, rheologies, and fault-slip phenomena. Here, we compile surface heat flow data from subduction zones worldwide and show that values are higher than can be explained for a frictionless subduction interface often assumed for modeling. An additional heat source--likely shear heating--is required to explain these forearc heat flow values. A friction coefficient of at least 0.03 and possibly as high as 0.1 in some cases explains these data, and we recommend a provisional average value of 0.05 ± 0.015 for modeling. Even small coefficients of friction can contribute several hundred degrees of heating at depths of 30-80 km. Adding such shear stresses to thermal models quantitatively reproduces the pressure-temperature conditions recorded by exhumed metamorphic rocks. Comparatively higher temperatures generally drive rock dehydration and densification, so, at a given depth, hotter rocks are denser than colder rocks, and harder to exhume through buoyancy mechanisms. Consequently--conversely to previous proposals--exhumed metamorphic rocks might overrepresent old-cold subduction where rocks at the slab interface are wetter and more buoyant than in young-hot subduction zones, Support was provided by NSF Grants EAR1419865 and OISE1545903 (to M.J.K.), EAR1447468 and EAR1750674 (to F.S.S.), and the Spanish Ministry of Science under “Acción de Programación Conjunta Internacional” Grant PCIN-2015-053 (to C.R.R.)

Background Anti-neutrophil cytoplasmic antibodies (ANCAs) are directed against the primary granules of neutrophils and monocytes and are essential in the diagnosis of vasculitis pauciimmune. The positivity of anti nuclear antibodies (ANAs) interferes with the interpretation of ANCAs leading to false positives. Objectives Evaluate the interference of ANAs in the interpretation of ANCAs in a population with manifestations of autoimmune disease Methods 3330 patient data involving ANCA requests between 2013 and 2015 were analyzed. Indirect immunofluorescence (IIF) was used to determine whether the samples had interference with ANAs through the L-ANCA system (Inmmunoconcepts®). Results were evaluated by the Generic assay kit ELISA® and CytoBead® ANCA (Generic Assays) to confirm positivity to MPO and/or PR3.The technical performance was evaluated by correlation analysis with Kappa values for data in which ANCAs was assessed at least by two techniques. Subsequently positivity of ANCAs was determined in a small sample of patients with clinical manifestations of autoimmune disease Results Positive ANCAS were found in 10.21% (340/3330) of the data, 40% (136/340) were C-ANCA and 60% (204/340) P-ANCA. Only 67 requests included specific anti-MPO and anti-PR3 assays, and 62.7% of these (42/67) were positive for ANCAs. ANAs were requested in 538 data resulting positive in 68.21% (367), predominantly homogeneous pattern. 12,64% of ANCAs positive data were also positive for ANAs, with P-ANCA in 83.72% of cases. The technique comparison included 44 samples positive for ANCAs evaluated by L-ANCA, CytoBead ANCA and ELISA. The correlation analysis showed high concordance between CytoBead and ELISA for PR3 (K=1.00 p CytoBead ANCA and ANCA-L, a very low concordance (K=0.17 p Conclusions The results suggest there is interference of ANAs in the positive P-ANCA results. IIF is an excellent technique for screening the presence of ANCAs while other methods such as anti-PR3 and anti- MPO by ELISA or microparticles assays are required for confirmation References Jennette JC, Falk RJ. Pathogenesis of antineutrophil cytoplasmic autoantibody-mediated disease. Nat. Rev. Rheumatol. 10, 463–473 (2014). Csernok E, Moosig F. Current and emerging techniques for ANCA detection in vasculitis. Nat. Rev. Rheumatol. 2014;10(8):494–501. Radice A, Bianchi L, Sinico RA. Anti-neutrophil cytoplasmic autoantibodies: Methodological aspects and clinical significance in systemic vasculitis. Autoimmun Rev 2013;12:487–95. Disclosure of Interest None declared