Serum amyloid A is expressed in histologically normal tissues from horses and cattle

mRNA expression of the acute phase protein serum amyloid A (SAA) in histologically normal tissues derived from horses ( n = 13) and cattle ( n = 4) was investigated by quantitative reverse-transcriptase real-time polymerase-chain reaction. As expected, high constitutive SAA mRNA expression was demonstrated in hepatic tissue in both species. In horses, moderate (>1% of the hepatic expression) SAA mRNA expression was detected in the lung, mammary gland, pancreas, synovial membrane, thymus, thyroid gland and uterus. Other equine tissues and organs sampled included adipose tissue, adrenal gland, aorta, brain, different gastro-intestinal tissues, heart, kidney, lymph node, ovary, testis, prostate, skeletal and cardiac muscle, skin and spleen; all showed low (