Immediate responses in serum tnfα and acute phase protein concentrations to infection with Pasteurella haemolytica A1 in calves

Abstract The concentrations of tumour necrosis factor-α ( tnf α ), serum amyloid A (sAA) and haptoglobin were determined in serum samples taken from four calves in the 10 hours after their intra-tracheal inoculation with Pasteurella haemolytica serotype A1. The concentration of haptoglobin did not increase but the concentration of saa rose progressively from within two hours of inoculation. The concentration of tnf α reached a peak in all the animals two hours after inoculation but had returned to undetectable levels after a further four hours. tnf α is likely to be an important mediator of the acute phase response in cattle and saa is a more rapid bovine acute phase protein than haptoglobin in its response to infection with P haemolytica .