THE PHYTOHEMAGGLUTININ [PHA] SKIN-TEST AS AN INDICATOR OF STRESS-INDUCED CHANGES IN IMMUNE REACTIVITY IN PIGS

The present study describes two experiments to standardize the phytoha emagglutinin (PHA) skin test as an indicator of lymphocyte reactivity in pigs after exposure to stressful situations in practical pig husban dry, The first experiment was a dose-response experiment, No time do se interaction was found, so the pattern of the reaction was the same for all doses used, although the magnitude of the reaction differed, T he second experiment was carried out to determine stress-induced chang es in lymphocyte reactivity, One half of a group of 48 pigs was expose d to stress (mixing, moving, and an increased stocking density), The i mmune reactivity to intradermally injected PHA of stressed animals dif fered significantly (P < 0.01) from that of unstressed controls, The r eaction of stressed animals can be characterized by a delayed reaction with a lower peak. It can be concluded that frequent measurements are preferable to single measurements when the effects of stress on immun ological processes are studied.