Eccrine Sweat as a Biofluid for Profiling Immune Biomarkers

Purpose Sweat is a relatively unexplored biofluid for diagnosis and monitoring of disease states. In this study, the proteomic profiling of immune‐related biomarkers from healthy individuals are presented. Experimental Design Eccrine sweat samples are collected from 50 healthy individuals. LC‐MS/MS is performed on two pools of sweat samples from five male and female participants. Individual sweat samples are analyzed by antibody isotyping microarrays (n = 49), human cytokine arrays (n = 30), and quantitative ELISAs for interleukin‐1α (n = 16), epidermal growth factor (n = 6), and angiogenin (n = 7). Results In sweat, 220 unique proteins are identified by shotgun analysis. Detectable antibody isotypes include IgA (100% positive; median 1230 ± 28 700 pg mL−1), IgD (18%; 22.0 ± 119 pg mL−1), IgG1 (96%; 1640 ± 6750 pg mL−1), IgG2 (37%; 292 ± 6810 pg mL−1), IgG3 (71%; 74.0 ± 119 pg mL−1), IgG4 (69%; 43.0 ± 42.0 pg mL−1), and IgM (41%; 69.0 ± 1630 pg mL−1). Of 42 cytokines, three are readily detected in all sweat samples (p