Effect of Pasteurella multocida vaccination on buffalo polymorphonuclear hydrogen peroxide and nitric oxide production

An attempt was made to investigate the effect of Pasteurella multocida on certain microbicidal reactive oxygen and nitrogen intermediates released by the polymorphonuclear cells (PMNs) from the vaccinated animals. The PMNs from the peripheral blood of both control and experimental buffaloes vaccinated against haemorrhagic septicaemia were isolated. PMNs from control animals upon activation with P. multocida lipopolysaccharide (LPS) and live P. multocida cells generated higher levels of hydrogen peroxide (H2O2) and nitric oxide (NO−) than the non-activated cells (P < 0.01). In the presence of P. multocida LPS, PMNs from animals vaccinated against haemorrhagic septicaemia generated significantly higher H2O2 (P < 0.05) and NO− (P < 0.01) than the PMNs from control animals. l-Arginine when added to the activation medium enhanced the production of NO− in a dose-dependent manner. This indicated the role of arginine in NO− production. The study suggested that buffalo PMNs possessed a potent oxidant defence system even in the presence of P. multocida, an antiphagocytic bacterium.