Study of responsible mechanisms for accumulation of the lymphocytes during the induced pleurisy for Mycobacterium bovis- BCG
In this study we evaluated the mechanism by which T cells accumulate in pleural cavity at different phases of BCG-induced inflammatory response. In the first part of this study we investigated the role of adhesion molecules from selectin family in the lymphocyte accumulation at pleural cavity after BCG stimulus. The intrathoracic (i.t.) injection of BCG (4.5 x 105 viable bacteria/cavity) induced a progressive accumulation of total leukocytes, mononuclear cells, granulocytes and T lymphocytes in C57BL/6 mice pleural cavity. The pretreatment with fucoidan was able to inhibit granulocyte accumulation at 24 hours and 15 days after stimulus, but failed to inhibit T lymphocytes accumulation at 15 days. Adoptive transfer of FITC-labeled cells to infected mice showed that lymphocyte migrated 24 hours but not 15 days after BCG-induced pleurisy. Furthermore, the expression of molecules involved in lymphocyte proliferation such as IL-2, its counter receptor CD25 and a monomer that compose the AP-1 complex, c-Fos, were evaluated 7 days after BCG stimulation. The content of IL-2 in pleural washes recovered from BCG-injected mice was higher than observe in control group. The expression of CD25 and c-Fos in pleural lymphocytes recovered from BCG stimulated mice were also higher than observed in saline-stimulated group. Moreover, pleural washes recovered 7 days after BCG-stimulation was able to induce lymphocyte proliferation due to IL-2 and IFN-. action. Taken together, these results suggest that T lymphocyte accumulation in pleural cavity observed at 15 days after BCG is due to a proliferative event. The second part of this study was dedicated to evaluate the lymphocyte chemotatic activity of CCL2/CCR2 during BCG-induced pleurisy. The i.t. injection of BCG increases the production of CCL2 by pleural cells within 24 hours that started to decrease within 7 days, and returned to basal levels at 15 days. .d T cells recovered from pleural cavity of BCG-stimulated mice expressed higher levels of CCR2 when compared to control mice, only at 24 hours after BCG injection. The role of CCL2/CCR2 on early .d T cell accumulation was confirmed in C57BL/6-CCR2-/- mice, which showed impaired .d T cell accumulation into the pleural space 24 hours after BCG-stimulation. The role of CCL2 in the acute phase of inflammatory response induced by BCG stimulus was assured by in vitro .d T cell migration towards cell-free pleural washes recovered from BCG-injected mice (BPW) within 24 hours (but not in response to 7- or 15-day BPW) as well as through adoptive transfer of labeled .d T cells that showed a pronounced .d T cell mobilization from peripheral blood into the inflamed tissue within 24 hours, but not 7 or 15 days after BCG i.t. stimulation. Together our results suggest that lymphocyte accumulation during the acute and late phase of inflammatory response to BCG stimulus derived from distinct but complementary mechanisms.
Advisor:Maria das Graças Muller de Oliveira Henriques
School:Faculdades Oswaldo Cruz
Source Type:Master's Thesis
Keywords:Quimiocinas Mycobacterium bovis Pleurisia Tuberculosis Pleural Cell Movement Chemokines T-Lymphocytes Pleurisy
Date of Publication:08/31/2006