Pentoxifylline treatment of mice with chronic pulmonary tuberculosis accelerates the development of destructive pathology

It is well established in animal models that production of the cytokine tumour necrosis factor-alpha (TNF-alpha) is essential to the proper expression of acquired specific resistance following infection with Mycobacterium tuberculosis. This gives rise to an apparent state of chronic disease which over the next 100-200 days is characterized by slowly worsening pathological changes in the lung. To determine whether continued TNF-alpha production was harmful during this phase mice were treated with a TNF-alpha inhibitor, pentoxifylline. It was observed that although this therapy did not alter the numbers of bacteria recovered from the lungs of the infected mice, tissue damage within the lung was accelerated. These data thus demonstrate that production of TNF-alpha, already known to be important during the early expression of resistance to tuberculosis, remains important and beneficial during the chronic stage of the disease.

Tuberculosis in aged gammadelta T cell gene disrupted mice

In young mice exposed to aerosol infection with Mycobacterium tuberculosis removal of the gammadelta T cell population by targeted gene disruption does not affect the expression of host resistance, but does influence the integrity of the early granulomatous response. The current study demonstrates that in aged gammadelta T cell gene disrupted mice similar immunopathologic changes ensued in both gene knockout and wild type control mice. Changes in cell surface marker expression, evident in other gene knockout models, was not observed in the aged gammadelta T cell knockout mice. These data imply that gammadelta T cell functions previously observed in young mice become much less important as the animal ages.