Changes

* Intense activation of T cells, [[Cytokines - WikiBlood|cytokine]] release and [[Macrophages - WikiBlood|macrophage]] activation cause necrosis of surrounding tissue, granuloma formation leading to destruction of host tissue.

* Intense activation of T cells, [[Cytokines - WikiBlood|cytokine]] release and [[Macrophages - WikiBlood|macrophage]] activation cause necrosis of surrounding tissue, granuloma formation leading to destruction of host tissue.

* Composed of epithelial cell, [[Macrophages - WikiBlood#Giant cells|giant cells]] and [[Macrophages - WikiBlood|macrophage]] in response to infection, for example:

* Composed of epithelial cell, [[Macrophages - WikiBlood#Giant cells|giant cells]] and [[Macrophages - WikiBlood|macrophage]] in response to infection, for example:

** [[Mycobacteria spp.|''Mycobacterium tubercle'']]

** [[:Category:Mycobacterium species|''Mycobacterium tubercle'']]

** Schistosome eggs

** Schistosome eggs

* Granulomas can obstruct normal organ function:

* Granulomas can obstruct normal organ function:

* Injection of intradermal antigen into the skin.

* Injection of intradermal antigen into the skin.

* A skin reaction (infiltration of lymphocytes and [[Monocytes - WikiBlood]]) peaking at 48-72 hours indicates prior exposure to the antigen or ongoing infection.

* A skin reaction (infiltration of lymphocytes and [[Monocytes - WikiBlood]]) peaking at 48-72 hours indicates prior exposure to the antigen or ongoing infection.

* It is used for TB testing cattle; the antigen is purified protein derivative-PPD from [[Mycobacteria spp.|''Mycobacterium tuberculosis'']].

* It is used for TB testing cattle; the antigen is purified protein derivative-PPD from [[:Category:Mycobacterium species|''Mycobacterium tuberculosis'']].

* Presently in the UK the animal is culled if it has a positive skin reaction.

* Presently in the UK the animal is culled if it has a positive skin reaction.