Th-1- and Th-2-type cytokine expression by activated T lymphocytes from the lung and spleen during the inflammatory response to respiratory syncytialvirus

RSV is an important cause of lower respiratory tract illness in infants and the elderly worldwide. The components involved in immunity and those that contribute to inflammation of RSV-induced disease are not clearly understoo d. To address the relationship between activation antigen and cytokine expr ession, intracellular levels of IL-2, IL-4, IL-5 and IFN-gamma were determi ned for CD3, CD44, CD49d, CD54, CD62L and CD102 lymphocytes from the bronch oalveolar lavage and spleen. To examine activation at the DNA level, lympho cytes expressing IL-2, IL-4, IL-5 or IFN-gamma were analysed for G2 + M DNA content or phosphatidylserine expression (apoptosis). Trafficking of lymph ocytes to the BAL was detected at day 5 p.i., peaked day 7 p.i., and predom inately involved CD54(+) and CD102(+) lymphocytes expressing high levels of IL-2, IL-4, IL-5 and IFN-gamma. Lymphocytes expressing CD44(+), CD49d(+) a nd CD62L(lo) were also observed, however they expressed these cytokines to a lesser extent. DNA analysis of lymphocytes expressing IL-2 or IFN-gamma r evealed higher G2'M levels compared to lymphocytes expressing IL-4 or IL-5, suggesting greater activation of Th-1-type lymphocytes in the lung. These data demonstrate that RSV-induced pulmonary inflammation involves extensive cellular activation and cytokine expression, particularly by CD54+ and CD1 02(+) lymphocytes in the lung. (C) 2000 Academic Press.