The effect of suppression and cytotoxic drugs on dinitrochlorobenzene induced delayed type hypersensitivity in the chicken.
Unresponsiveness to dinitrochlorobenzene (DNCB) in chickens sensitised with a supraoptimal dose of DNCB (2.5 mg/bird) is an active process mediated by spleen lymphoid cells. Preparations of spleen lymphocytes/monocytes, or non-adherent spleen lymphocytes alone, from supraoptimally sensitised chickens, when transferred into optimally sensitised outbred chickens (1 mg DNCB/bird) suppressed the normal delayed type hypersensitivity (DTH) reaction to DNCB. The suppressive effect of these MHC unrestricted suppressor cells was abrogated in supraoptimally sensitised birds by pretreatment with dexamethasone, cyclophosphamide or 6-mercaptopurine. The effects of these cytotoxic drugs depended on the sensitising dose and the timing of drug administration in relation to sensitisation. Only DTH responses in chickens sensitised to supraoptimal doses of DNCB were enhanced by drug treatment prior to sensitisation. The responses of optimally sensitised birds was not affected. Cyclophosphamide or 6-mercaptopurine, but not dexamethasone, decreased the response of optimally sensitised birds treated after sensitisation.
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Department of Biochemistry, Microbiology and Nutrition, University of New England, Armidale, N.S.W., Australia.
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