T-cell dependent inflammatory responses

Abstract

Delayed type hypersensitivity (DTH) is a T-cell dependent inflammatory response at the site of antigen deposition, usually in the skin. It reaches its peak intensity 24–48 h after initiation and is characterized by a mononuclear cell infiltration. T cells, but not B cells nor immune serum, can transfer the reaction to naive animals. The measurement of the intensity of DTH involves quantifying the inflammatory response at the site of antigen deposition. Redness and induration can be measured in man and in certain animals such as the guinea pig. In mice, ear thickness increase or footpad swelling may be used. Alternatively, a radioactive precursor of DNA ([125I]UdR) can be injected systemically to label the progenitors of the mononuclear cells which enter inflammatory sites. The intensity of the DTH reaction in a defined site, such as an ear where antigen is injected intradermally, will be proportional to the radioactivity obtained. The results may be expressed as the ratio of the radioactivity of the challenged (left, L) ear to the unchallenged (right, R) ear (L/R[125I]UdR uptake)1.