Human mitochondrial diseases associated with tRNA wobble modification deficiency.

BACKGROUND

The precise mechanisms involved in the pathogenesis of hypersensitivity pneumonitis (HP) have not been identified. HP is characterized by inflammatory lymphocytic alveolitis and a remarkable increase in T-lymphocytes detected in bronchoalveolar lavage fluid (BALF). It is suggested that both CD4+ and CD8+ T cells may contribute to the pathogenesis of HP. Experiments on animal models suggest that cell mediated immunity (CMI) is more important for the pathogenesis of HP than complex-mediated immunity, but the relationship between the subsets of BALF lymphocytes and humoral or cell-mediated allergic reactions is still not clear. The aim of our study was distinguish CD4+ and CD8+ T cells in BALF lymphocytes during a delayed-type hypersensitivity (DTH) reaction in the lung.

MATERIAL AND

METHODS

The experiment was performed on guinea pigs sensitized with BCG vaccine and subjected to a single inhalation of tubercle bacilli antigens (tuberculin). 24 hours after tuberculin provocation (at the time of maximum lymphocyte infiltration), bronchoalveolar lavage was performed on both sensitized and non-sensitized (control) animals. The total cell count was estimated, and a differential microscopical examination of BAL-fluid cells was performed, along with the phenotyping of BALF lymphocytes (by flow cytometry).

RESULTS

In the BALF of the sensitized animals, as compared to the controls, there was a statistically significant increase in the percentage and absolute count of T-lymphocytes, CD4+ and CD8+. The CD4 / CD8 ratio in both groups did not differ significantly and was individually variable (2.94I0.72 SEM in the experimental group, vs 4.41I1.29 SEM in the control group).

CONCLUSIONS

Both CD4+ and CD8+ lymphocytes (with some predominance of helper cells) participate in the efferent phase of the delayed type hypersensitivity reaction in the lung induced by antigen inhalation.