Cellular immunity in tuberculosis

The role of cellular immunity was studied using in vitro techniques for observing rates of phagocytosis and cytopepsis. Peritoneal exudates were stimulated using standard techniques and alveolar phagocytes were harvested by a technically less difficult method than used by others. This procedure yielded higher cell counts than those obtained by existing methods. Alveolar and peritoneal phagocytes were harvested from normal and BCG immunized guinea pigs. The hypothesis examined was that cells from immunized guinea pigs would have increased capacities for phagocytosis and cytopepsis of virulent (H37Rv) and avirulent (H37Ra) strains of tubercle bacilli. Various types of culture media and conditions were screened in order to select the optimal conditions for the planned experiments. Suspensions of tubercle bacilli dispersed by wetting agents were unsatisfactory for use in determining rates of phagocytosis. Those suspensions prepared by filtration, when exposed to normal and immune phagocytes, yielded results that indicated there may be differences between normal and immune phagocytes. The area of the body from which the phagocytes are harvested may also impart differences in rates of phagocytosis and cytopepsis. Preliminary studies were carried out concerning the role of antibody in the systems previously described. Although the antibody had no observable effect on the immune cells, normal cells seemed to benefit from the presence of antibody by showing increased rates of cytopepsis. Further work is needed in this area of investigation which is designed to yield information concerning mechanisms of resistance to mycobacterial disease.