T cell redistribution kinetics after secondary infection of BALB/c mice with respiratory syncytial virus

Abstract

SUMMARYBALB/c mice were infected intranasally with live respiratory syncytial virus (RSV) and reinfected 4 weeks later. At regular intervals thereafter groups of animals were killed and T cell subsets were determined in blood, spleen and bronchoalveolar lavage (BAL) with flow cytometry employing T cell subset-specific MoAbs. Total lymphocyte counts in the peripheral blood decreased 1-3 days after infection, returning to preinfection levels on day 8 (/" = 00111). Simultaneously, a marked increase of lymphocytes was noted in the BAL, reaching a maximum at day 8 (/'<0 0001). Both CD4+ and CD8 + T cells decreased in the blood on day 1 -3 (P < 0 0097 and P = 0 003 respectively), and increased in the BAL progressively towards a maximum at day 8 (/'<0 0001). In BAL, CD4+ cells increased 35-fold and CD8+ cells 27-fold during the first week after reinfection. On the other hand, in the spleen a significant decline of CD4+ and CD8+ cells was noted 1 day post-infection (P = 0 0002). It is concluded that a strong T cell redistribution response among systemic and mucosal tissues occurs after reinfection with RSV. The kinetics of this response differ both quantitatively and qualitatively from the T cell response after primary infection. The magnitude of cell traffic is more pronounced in blood, spleen and BAL than after primary infection. CD4+ T cells are more intensively distributed to the lungs than after primary infection.

The Host Response and Molecular Pathogenesis Associated with Respiratory Syncytial Virus Infection

“…Studies have demonstrated that virus clearance is temporally associated with an increase of RSV-specific CD8 cytotoxic T-lymphocyte activity in the lungs [200]. Although T-cell responses to RSV infection predominantly occur in the lungs, it has been demonstrated in a mouse model that T-cell subsets can redistribute to secondary sites following RSV infection [201]. A higher proportion of RSV-specific CD8 + T cells in the peripheral blood have been observed in older infants than younger infants, a feature that might be due to immune immaturity, the Th2-type environment in the lungs or the suppressive effect of maternal antibodies.…”