IMMEDIATE RESPONSES IN SERUM TNF-ALPHA AND ACUTE-PHASE PROTEIN CONCENTRATIONS TO INFECTION WITH PASTEURELLA-HAEMOLYTICA A1 IN CALVES

The concentrations of tumour necrosis factor-alpha (TNF alpha), serum amyloid A (SAA) and haptoglobin were determined in serum samples taken from four calves in the 10 hours after their intra-tracheal inoculati on with Pasteurella haemolytica serotype A1. The concentration of hapt oglobin did not increase but the concentration of SAA rose progressive ly from within two hours of inoculation. The concentration of TNF alph a reached a peak in all the animals two hours after inoculation but ha d returned to undetectable levels after a further four hours. TNF alph a 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 haptog lobin in its response to infection with P haemolytica.