Immunopathology of Pulmonary Granulomas

Abstract

Granulomatous-type inflammations can be divided into two general categories: (a) nonimmunologic or foreign body type and (b) immunologic or hypersensitivity type. The foreign body type granulomas are readily produced experimentally with substances like carrageenan, plastic beads, bentonite, talc and certain microbial cell-wall products, such as mycobacterial cord factor. The major principle involved in these types of granulomas is that the irritant is usually water insoluble and slowly digestible or nondigestible. Accordingly, it represents the basic cellular response of chronic inflammation which is dominated by macrophage mobilization to the site of the irritant. As a rule, the lymphocyte response is minimal and the level of macrophage activation is limited. The characteristic response in this case is that repeated injections of these types of irritants produce the same time course in the evolution of the lesion (1).