Eccrine Sweat as a Biofluid for Profiling Immune Biomarkers. Issue 6 (28th June 2018) - Katchman, Benjamin A.
Abstract : 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 < 0.01). The median concentration for interleukin‐1α is 352 ± 521 pg mL −1, epidermal growth factor is 86.5 ± 147 pg mL −1, and angiogenin is 38.3 ± 96.3 pg mL −1 . Multiple other cytokines are detected at lower levels. Conclusions and Clinical Relevance: Sweat can be used for profiling antibodies and innate immune biomarkers.