Effects of dexamethasone on distribution and function of peripheral mononuclear blood cells in pneumonic calves.

Experimental pneumonic pasteurellosis was used in 30 Holstein calves to compare the effects on the immune response of different treatments: antibiotics alone or antibiotics in combination with either steroidal (SAID) or non-steroidal anti-inflammatory drugs (NSAID). Clinical parameters and the effect of treatments on the mitogen-induced proliferation of peripheral mononuclear blood cells (PMBCs) and on their distribution were evaluated. Calves in all three treated groups showed rapid improvement, but clinical signs were less marked in both groups receiving anti-inflammatory drugs. Limited difference in the effect on the immune system of treatments was observed. No inhibition of lymphocytes proliferation was detected in these experimental conditions in the dexamethasone (DM)-treated group. There was no variation among groups for the CD4+, CD5+, CD8+ and CD21+ populations. The only noteworthy change was a transient increase in the percentage of the monocyte population (CD14+) in the DM-treated group compared to the group treated with NSAID.