A comparison of serum and plasma cytokine values using a multiplexed assay in cats.

BACKGROUND: Degenerative joint disease (DJD) is highly prevalent in cats, and pain contributes to morbidity. In humans, alterations of cytokine concentrations have been associated with joint deterioration and pain. Similar changes have not been investigated in cats. Cytokine concentrations can be measured using multiplex technology with small samples of serum or plasma, however, serum and plasma are not interchangeable for most bioassays. Correlations for cytokine concentrations between serum and plasma have not been evaluated in cats.

OBJECTIVE: To evaluate the levels of detection and agreement between serum and plasma samples in cats.

ANIMALS: Paired serum and plasma samples obtained from 38 cats.

METHODS: Blood was collected into anti-coagulant free and EDTA Vacutainer® tubes, serum or plasma extracted, and samples frozen at -80°C until testing. Duplicate samples were tested using a 19-plex feline cytokine/chemokine magnetic bead panel.

RESULTS: Agreement between serum and plasma for many analytes was high, however correlation coefficients ranged from -0.01 to 0.97. Results from >50% of samples were below the lower limit of quantification for both serum and plasma for nine analytes, and for an additional three analytes for plasma only.

CONCLUSIONS AND CLINICAL IMPORTANCE: While serum and plasma agreement was generally good, detection was improved using serum samples.