RADIOMETRIC EAR INDEX TEST AS A MEASURE OF DELAYED-TYPE HYPERSENSITIVITY IN RAT

Google Scholar
  • 1 January 1977
    • journal article
    • research article
    • Vol. 33  (4) , 561-571
Abstract
Intradermal skin tests performed in the pinna of the rat ear appeared to be 100 times more sensitive than classical flank skin tests in measuring Arthus and delayed-type hypersensitivity (DTH) reactions. One of these tests was antigen-induced thickening of the pinna of the ear. It was a sensitive measure of Arthus reactivity at 4 h after irritation with antigen in actively immunized rats and recipients of precipitating immune serum. The other test, radiometric ear index determination, exploits the fact that monocytes and monocyte derived macrophages accumulate at DTH reaction sites. The test was performed by labeling the precursors of these cells with a pulse of [3H]-thymidine and by determining radioactivity in biopsy specimens taken from test sites in the pinna of the ear. At a certain antigen dose range this objective and highly sensitive method measured a purely cell mediated reaction which could be transferred to normal recipients with thoracic duct lymphocytes but not with immune serum. It also behaved as a typical DTH reaction in response to desensitizing injections of the specific antigen. Testing with unnecessarily high antigen doses should be avoided since the strong early inflammation induced by them may interfere with the determination of DTH while using this sensitive assay.