Fig 1: Autoantibodies in COVID-19 patients are functional and correlated with virological and immunological parameters in vivo.a, GM-CSF signaling assay based on STAT5 phosphorylation performed in the presence of various concentrations of purified IgG from a COVID-19 patient with GM-CSF autoantibodies and uninfected control plasma samples. Details of percent max signal calculation can be found in methods. Curves were fit using a sigmoidal 4 parameter logistic curve. Results are averages of 2 technical replicates. b, CXCL1 and c, CXCL7 signaling assay performed in the presence of 0.05 mg/mL purified IgG from a COVID-19 patient with CXCL1 or CXCL7 autoantibodies and uninfected control plasma samples. Results are averages of 3 technical replicates. Significance was determined using a two-sided unpaired t-test (p = 0.0055 in b and 0.0069 in c). d, Hierarchically clustered heatmap of IFNa REAP reactivities across all samples. e, Longitudinal comparisons of SARS-CoV-2 viral load between patients with and without anti-interferon antibodies. Viral loads were estimated by plotting nasopharyngeal, saliva, or by averaging saliva and nasopharyngeal samples where both were present, in order to generate composite viral loads for each patient. Linear regressions for each group are displayed (solid lines). f, Percent B cells among peripheral leukocytes and g, anti-SARS-CoV-2 RBD IgM reactivity as measured by ELISA in samples stratified by COVID-19 disease severity and REAP reactivity (AAb+; REAP score > 2) against B cell displayed proteins (CD38, FcµR, FCRL3). h–j, Percentage among total monocytes of classical monocytes (h), intermediate monocytes (i), and nonclassical monocytes (j) in samples stratified by COVID-19 disease severity and REAP reactivity (AAb+; REAP score > 2) against proteins preferentially displayed on classical and intermediate monocytes (CCR2, CCRL2, FFAR4, SYND4, and CPAMD8). Data from f–j were presented as boxplots with the first quartile, median, third quartile, and individual data points indicated. k, Results from h–j represented as horizontal bar charts. Significance was determined using two-sided, Wilcoxon rank-sum test; *P = 0.05, **P = 0.01, ***P = 0.001, ****P = 0.0001. All error bars in this figure represent standard deviation.