[Delayed type hypersensitivity and Immunity (author's transl)]

Delayed type hypersensitivity is a T-cell-mediated phenomenon. It is characterized by the following features: a) development within 24-72 h after antigen challenge in sensitized individuals, b) perivascular infiltration by mononuclear cells at the inflammatory site, c) transfer by lymphocytes, but not by serum. Delayed type hypersensitivity occurs during infections with facultatively intracellular bacteria and certain viruses, tumor diseases and rejection of transplanted foreign tissue. This article samples evidence that delayed type hypersensitivity is an outward phenomenon indicating the presence of specific T-cells and mononuclear phagocytes, both acting together to produce local immunity which results in the elimination or containment of the noxious agent.