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Unformatted text preview: pig is simultaneously injected with both LM and MT, it survives. These results tell us that: The reaction elicited by antigen occurs relatively slowly (hence the name "delayed hypersensitivity"). The hypersensitivity is mediated via T-cells and macrophages. The hypersensitivity illustrates both antigen-specific (T-cell) and antigen non-specific (macrophage) characteristics. The details of this reaction can be summarized as follows ( click the image to animate ): 1. Initial introduction of antigen produces a cell-mediated response. Mycobacterium tuberculosis is an intracellular pathogen and recovery requires induction of specific T-cell clones with subsequent activation of macrophages. 2. Memory T-cells respond upon secondary injection of the specific (i.e. MT) antigen, but not the non-specific (i.e. LM) antigen. 3. Induction of the memory T-cells causes activation of macrophages and destruction of both specific (MT) and non-specific (LM) microorganisms....
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- Fall '10