DELAYED-HYPERSENSITIVITY AND IMMUNITY IN TUBERCULOSIS

Publisher Website
Google Scholar
Abstract
The in vitro correlates of delayed hypersensitivity [DTH] and immunity, the nature of desenitization in DTH and the classification of lymphocytes into functionally diverse subpopulations are discussed. The phenomena associated with cell-mediated immunity require the action of thymus-derived [T] cells both as initiator and effector cells. During the development of cell-mediated immunity a diverse spectrum of T cell functions is generated. In the present context it is irrelevant whether such diversity is produced by generically separate clones of T cells or whether a single clone of cells can perform various functions at separate stages in its development. Although T cells with differing functions can be isolated from immunized animals, it seems improbable that animals could be immunized in such a way as to promote the expression of a single T cell function. This statement does not preclude the possibility that in certain situations one function may predominate at the expense of others, e.g., a BCG-immunized animal might lack rapid T cell functions, such as migration inhibitory factor [MIF] production and DTH, but possess slow T cell functions, such as blast transformation. After challenge with tubercle bacilli this animal might develop immunity, DTH and MIF-producing cells more rapidly than non-immunized control subjects. Only in the narrowest sense could such an animal be considered nonhypersensitive before reinfection. The practical implication of the hypothesis presented is that nonallergenic immunizing agents in tuberculosis may be hard, if not impossible, to find. No claim should be made for such agents without exhaustively testing several parameters of cellular hypersensitivity so as to ensure that the materials are truly nonsensitizing.