Mononuclear cell function in Mycobacterium tuberculosis infected guinea pigs.

In this study mononuclear cell function was studied in the lymph glands, spleen, and peripheral blood of Mycobacterium tuberculosis infected guinea pigs. Adherent cells from draining lymph nodes and spleens of infected animals spontaneously produced a factor which inhibited normal lymphocyte proliferative responses. As it has previously been shown that this factor activates a population of suppressor T cells, resident lymphocytes in the lymph nodes and spleen were examined and were shown to inhibit normal lymphocyte functions. It is suggested that adherent cells ingesting M. tuberculosis spontaneously release a suppressor cell activating factor (SCAF) which locally activates lymphocytes to become suppressor cells. Even at a time of overwhelming infection, peripheral blood adherent cells could not be shown to release SCAF and peripheral blood suppressor cells could not be identified. Although peripheral blood lymphocyte proliferative responses to PHA were normal in infected animals, their ability to produce the lymphokine macrophage inhibition factor was considerably reduced after the second week of infection. This dissociation between lymphocyte proliferation and lymphokine production is similar to that previously described in humans overwhelming tuberculosis.