Serum concentrations of canine interleukin-1 receptor antagonist protein in healthy dogs after incubation using an autologous serum processing system

•Autologous serum systems that enrich IL-1RA may prove useful for treating canine osteoarthritis.•A linear, accurate, precise, and repeatable canine IL-1RA ELISA has yet to be described.•We report the optimization and validation of a canine IL-1RA ELISA for use on canine serum.•Using this ELISA, IL-1 RA levels in healthy canine blood are 396.6 ± 208.0 pg/mL (mean ± SD).•IL-1 levels increased to 15,955.0 ± 6421.0 pg/mL after treatment with an autologous serum system.

The objectives of this study were to optimize and validate a canine IL-1RA ELISA using commercially available reagents and to determine the effect of an autologous serum processing system (IRAP II) on IL-1RA concentrations in canine serum. The clinical detection limit of the optimized ELISA was 188.8 to 39,965.6 pg/mL. The observed-to-expected ratio (O:E) for three serial dilutions for four serum samples ranged from 109.6 to 132.2%. The O:E for four serum samples spiked with four concentrations of canine IL-1 RA ranged from 98.7 to 114.3%. Coefficients of variances for intra- and interassay variability ranged from 1.4 to 3.0 and 6.3 to 9.8, respectively. The ELISA was sensitive, linear, accurate, precise, and reproducible. Mean ± SD serum concentration of IL-1RA in 12 healthy dogs was 396.6 ± 208.0 pg/mL. There was a significant increase in IL-1RA when blood was incubated in the IRAP II system (15,955.0 ± 6421.0 pg/mL, P < 0.0001).