Delayed type hypersensitivity and immunity against aerogenic tuberculosis in guinea pigs

Abstract

The view that acquired resistance in tuberculosis is effected by cellular mechanisms of delayed type hypersensitivity was first clearly formulated by Romer in 1908. Over the past decade intimate relationships have been experimentally established between delayed tuberculin type hypersensitivity (DTH), thymus derived or thymus influenced lymphocytes (T cells) and the 'activation' of macrophages, the host cells of facultative intracellular parasites. It was concluded that immunological protection against infection with such parasites (e.g., Listeria and M. tuberculosis) and DTH, because they appear to be mediated by the same population of T cells, are causally related. These studies were carried out with mice, and the evidence is largely based on morphological grounds and on temporal parallelism between the development of hypersensitivity reactions in the footpads and evidences of antibacterial immunity in vivo. The purpose of this report is to describe the results of studies on the relationship between DTH and immunity against aerogenic challenge with virulent M. tuberculosis in guinea pigs vaccinated with M. bovis BCG or rendered hypersensitive to tuberculoproteins by other means. It was observed that guinea pigs with delayed type hypersensitivity to tuberculoproteins under various experimental conditions, with or without passive transfer of serum from immune donors, manifested no acquired immunity against aerogenically induced tuberculosis. These results are discussed in relation to previous observations of other investigators and to the general problem of cellular hypersensitivity and immunity against facultative intracellular bacteria.