Immunological features of tuberculosis

Some aspects of cell-mediated immunity were explored in a population of 51 patients with active pulmonary tuberculosis in comparison with 30 apparently healthy volunteers randomly taken from the Mexican general population. Evaluation included DNCB sensitization, PPD skin test, determination of LIF, E and EAC-rosette formation and the ability of lymphocytes to survive in culture through periods of up to 48 hours. The results for the in vivo assays showed significant differences between the compared populations since the frequency of a positive PPD skin test was higher in the patients (p = 0.0000004) but only 60.8% of them responded to DNBC (p = 0.006). It was expected that there would be some impairment in the production of LIF and in the number of E-rosettes, however, this did not occur. Survival of lymphocytes in culture demonstrated an altered population of cells, probably weak even before blood samples were taken, in the tuberculosis group (p = 0.05). Furthermore, cell mortality was very notable in patients with cavitated and infiltrative lesions, after 48 hours culture (p = 0.015 and 0.02 respectively) suggesting the presence of a population of cells unable to function optimally.