title: Mechanisms of T-lymphocyte accumulation during experimental pleural infection induced by Mycobacterium bovis BCG.
abstract: Tuberculous pleurisy is a frequent extrapulmonary manifestation characterized by accumulation of fluid and inflammatory cells in the pleural space. Here, we investigated the mechanisms of T-lymphocyte accumulation in the pleural space by using a murine model of pleurisy induced by Mycobacterium bovis BCG. Intrathoracic (i.t.) injection of BCG (4.5 x 10(5) bacteria/cavity) induced accumulation of T lymphocytes in the pleural cavities of C57BL/6 mice. We observed the presence of CFU in pleural washes conducted 1, 2, 3, 7, and 15 days after pleurisy induction. Pretreatment with fucoidan inhibited T-lymphocyte accumulation at 1 day, but not at 15 days, after BCG-induced pleurisy. Accordingly, adoptive transfer of fluorescein isothiocyanate-labeled blood mononuclear cells to infected mice showed that T lymphocytes migrated into the pleural cavity 1 day (but not 15 days) after BCG injection. Cell-free pleural wash fluids recovered from mice 1 day after BCG i.t. stimulation (day 1 BCG-PW), but not day 7 or day 15 BCG-PW, induced in vitro T-cell transmigration, which was dependent on L-, P-, and E-selectins. In contrast, day 7 BCG-PW (but not day 1 BCG-PW) induced in vitro T-lymphocyte proliferation via interleukin-2 (IL-2) and gamma interferon (IFN-gamma). Accordingly, in vivo IL-2 or IFN-gamma neutralization abolished T-lymphocyte accumulation 7 days after pleurisy induction. Our results demonstrate that pleural infection induced by BCG leads to T-lymphocyte accumulation in two waves. The acute phase depends on selectin-mediated migration, while the second wave of T-lymphocyte accumulation seems to depend on a local proliferation induced by cytokines produced in situ.
authors.affiliation: Laboratório de Farmacologia Aplicada, Departamento de Farmacologia Aplicada, Farmanguinhos, Fundação Oswaldo Cruz, Rua Sizenando Nabuco 100, Manguinhos, Rio de Janeiro 21041-250, Brazil.
authors.forename: Mariana C
authors.initials: MC
authors.lastname: Souza
authors.forename: Carmen
authors.initials: C
authors.lastname: Penido
authors.forename: Maria F S
authors.initials: MF
authors.lastname: Costa
authors.forename: Maria Graças
authors.initials: MG
authors.lastname: Henriques
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D002634:Chemotaxis, Leukocyte / Q000276:immunology*; D016207:Cytokines / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009163:Mycobacterium bovis / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D013995:Time; D014396:Tuberculosis, Pleural / Q000276:immunology*
chemical_list: D016207:Cytokines