IN-VITRO INTERLEUKIN-1 AND TUMOR-NECROSIS-FACTOR-ALPHA PRODUCTION BY MACROPHAGES FROM CHICKENS INFECTED WITH EITHER EIMERIA-MAXIMA OR EIMERIA-TENELLA

We measured the in vitro production of interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF- ) by macrophages from chickens during and immediately following an infection with one of two different species of Eimeria, E. maxima and E. tenella. Quantitatively, the amounts of IL-1 produced during each infection were nearly identical regardless of the oocyst dose of each parasite. TNF production followed a biphasic pattern of increased production with the first peak associated with the pathogenesis of disease and the second peak associated with the development of protective immunity. These experiments together with others we have reported imply cells taken from chickens infected with coccidia have a greater capacity to produce cytokines upon stimulation in vitro than cells from non-infected birds. The production of significantly greater amounts of TNF during the days 3-6 after inoculation correlates with the appearance of the most characteristic local and systemic pathophysiological changes in the host induced by the coccidia. The excessive release of TNF in response to a heavy coccidial infection may account for many of the pathological features observed with avian coccidiosis probably through the release of other mediators.