Effects of stress on leukocyte trafficking and immune responses: implications for vaccination.

Increased susceptibility of animals to infectious disease during the periparturient period results in suffering and economic losses. Stress appears to delay inflammation by reducing efficiency of CD62L-mediated immune surveillance by phagocytes. It is important to note that the effects of stress are not limited to alteration of leukocyte trafficking patterns since various stressors (e.g., transport, parturition, and castration) also decrease IFN-gamma secretion by lymphocytes, and may decrease antigen presentation efficiency by down-regulating class II molecule expression on antigen presenting cells, and delay or impair immune responses to vaccination. Documented immunosuppression in periparturient animals, particularly the bias toward Th2 immune responses, and also changes in general leukocyte trafficking patterns suggest that vaccination intending to elicit cell-mediated immunity may not be efficacious at this point of the production cycle. Based on findings of numerous periparturient studies on immunosuppression in cattle, waiting at least 30 days after parturition before administering routine vaccinations is recommended.