Effect of development and aging on the response of canine lymphocytes to phytohemagglutinin

The stage of development and age were found to effect the responsiveness of dog T-lymphocytes to phytohemagglutinin. T-lymphocytes from beagles 0 to 4 weeks of age showed significantly less response to phytohemagglutinin (P < 0.001) than T-lymphocytes from these same dogs at 6 to 12 weeks of age. Peak response to phytohemagglutinin occurred between 6 weeks to 6 months of age, after which there was a significant correlation (P < 0.02) between increase in age and decrease in phytohemagglutinin responsiveness.