Intradermal mitogen response in dogs: correlation with outcome of infection by canine distemper virus.

Gnotobiotic and conventional dogs of different ages were examined for intradermal skin test responses and in virtro peripheral blood lymphocyte responses to the phytomitogens, phytohemagglutinin-P (PHA-P) and pokeweed mitogen (PWM). All adult dogs skin tested with these mitogens demonstrated a positive skin reaction consisting of erythema and induration within 24 hours. In contrast, a positive reaction was obtained only with PHA-P when both mitogens were tested in conventional and gnotobiotic neonatal dogs. Lymphocytes from both adult and neonatal dogs underwent blastogenesis if cultured with PHA-P and PWM. Infection of gnotobiotic dogs with canine distemper virus (CDV) resulted in depression of PHA-P skin test response along with in vitro depression of lymphocyte blastogenesis. Persistent loss of skin test response correlated with eventual death due to CDV-associated encephalitis, whereas dogs which responded to PHA-P 14 to 21 days after viral inoculation survived CDV infection. The results of this study indicated that intradermal mitogen tests can be used as a rapid method for in vivo assessment of cell-mediated immunity in this species.