BIPHASIC GRAFT VS HOST RESPONSE IN AGING CHICKENS

The graft vs host (GvH) and phytohemagglutinin (PHA) wattle responses were the parameters chosen to evaluate cell-mediated immunity in aging chickens. At 6 and 24 months of age female spleen cells were significantly more effective in eliciting a GvH response than spleen cells from 1-, 2-, 12-, and 18-month-old females. The biphasic GvH response produced by female spleen cells was not observed for male spleens. On the other hand, peripheral blood lymphocytes from both males and females exhibited a single peak, 3-6 months, in their ability to produce a GvH response. The thymic-dependent PHA wattle response of males was significantly greatest at 1 month of age and declined thereafter. Once again the females exhibited a different pattern than the males. At 1 month of age the female's wattle response was significantly greater than at 3 months, but rather than declining with age the wattles of aging females responded like 1-month-old females. Several mechanisms are offered to explain the apparent age-related regression-regeneration of cell-mediated immunity in the female. © 1979.