Stability of five candidate reference genes in PBMC samples using geNorm and NormFinder analysis. Abbreviations. PBMC, peripheral blood mononuclear cells. Abbreviations for reference genes, see Table 1. PBMCs were cultured with medium (unstimulated condition) or stimulated with 5 μg/ml of Concanavalin A (stimulated condition) for 36 h. Stability of the five reference genes were calculated in bovine (A), caprine (B) and ovine (C) PBMC samples using geNorm application and NormFinder software. Stability values were calculated as M-value in geNorm and ρ-value in NormFinder. The reference genes were presented in ranked list of the most stable gene to the least stable gene. The pairwise variation (V-score) was performed with geNorm application to determine the optimal number of required reference genes for relative expression in bovine (A), caprine (B) and ovine (C) PBMC samples.