Delayed-type hypersensitivity, contact sensitivity, and phytohemagglutinin skin-test responses of heat- and cold-stressed calves.
Three-week-old Holstein bull calves were used to investigate the effect of a 2-week chronic heat (35 C) or cold (-5 C) exposure on delayed-type hypersensitivity (DTH) reactions to purified protein derivative after sensitization with heat-killed Mycobacterium tuberculosis, contact sensitivity (CS) reactions to 1-fluoro-2,4-dinitrobenzene, and phytohemagglutinin (PHA) skin tests. Heat exposure reduced expression of DTH reactions by 42% and CS reactions by 38% at 24 hours after elicitation of the responses. The PHA-induced skin tests were not affected after 1 week of heat exposure, but this reaction was reduced by 20% after 2 weeks of heat exposure. The immune response of calves exposed to cold air temperatures was more complex. Cold exposure suppressed CS reactions by 39% at the end of both the 1st and 2nd weeks. The PHA response was reduced by 39% after 2 weeks of cold exposure. The DTH response depended on duration of cold exposure. The DTH reaction was increased by 42% after 1 week, but was reduced by 14% after 2 weeks. These data are consistent with the hypothesis that environmental stressors alter host resistance by affecting the immune system. Furthermore, these stress-induced changes in immune events depend on the type of immune response, the nature of the environmental stressor, and the length of time that calves are exposed to the stressor.
D000818:Animals; D002417:Cattle / Q000276:immunology*; D003080:Cold Temperature; D004139:Dinitrofluorobenzene / Q000276:immunology; D006358:Hot Temperature; D006968:Hypersensitivity, Delayed / Q000276:immunology / Q000662:veterinary*; D008297:Male; D010835:Phytohemagglutinins / Q000494:pharmacology*; D012882:Skin Tests / Q000662:veterinary*; D013312:Stress, Physiological / Q000276:immunology / Q000662:veterinary*; D014374:Tuberculin Test / Q000662:veterinary
D010835:Phytohemagglutinins; D004139:Dinitrofluorobenzene