PMID- 31420068 OWN - NLM STAT- MEDLINE DCOM- 20191104 LR - 20191210 IS - 1873-2534 (Electronic) IS - 0165-2427 (Linking) VI - 215 DP - 2019 Sep TI - Development, analytical validation, and initial clinical evaluation of a radioimmunoassay for the measurement of soluble CD25 concentrations in canine serum. PG - 109904 LID - S0165-2427(19)30212-0 [pii] LID - 10.1016/j.vetimm.2019.109904 [doi] AB - During immune activation, CD25 is expressed by T cells, and its soluble form (sCD25) is released into the extracellular matrix and the bloodstream. In humans, serum sCD25 concentrations are used as a surrogate marker for autoimmune diseases, malignancies, and transplant rejection. However, a canine-specific assay for the measurement of sCD25 in dog serum has not previously been described. Therefore, the aims of this study were to develop and analytically validate a radioimmunoassay to measure sCD25 in canine serum, to establish a reference interval for canine sCD25, and to test the clinical utility of this assay with serum samples for dogs with various diseases. A competitive radioimmunoassay (RIA) was developed and analytically validated. Analytical validation consisted of lower limit of detection (LLOD), dilutional parallelism, spiking recovery, and intra- and inter-assay variability using pooled surplus canine serum samples. A reference interval was established in healthy dogs and serum samples from dogs with various types of neoplasia, IBD, liver disease, suspected pancreatitis, or suspected small intestinal disease and serum samples with an increased C-reactive protein concentration (CRP) were analyzed to test the clinical utility of the assay. LLOD was calculated to be 0.5 ng/mL. The mean (+/-SD) observed-to-expected ratio (O/E) for serial dilutions was 101.7 +/- 14.0%, and the mean (+/- SD) O/E for spiking recovery was 93.2 +/- 4.2%. Coefficients of variation (CVs) for intra-assay variability were