Source:http://linkedlifedata.com/resource/umls/id/C0034131
NCI: A purified protein extract derived from the bacterium Mycobacterium tuberculosis. Intradermally-administered, PPD stimulates preprimed CD4 T cells in immunologically competent subjects previously exposed to the bacterium Mycobacterium tuberculosis; these activated CD4 T cells secrete various cytokines that attract granulocytes, monocytes, and macrophages in an inflammatory response known as delayed hypersensitivity. (NCI04)