Different expression of ICAM-1 and LFA-1 alpha by peripheral leukocytes during respiratory syncytial virus and influenza virus infection in young children

We compared the expression of intercellular adhesion molecule (ICAM)-1 and lymphocyte function-associated antigen (LFA)-1 alpha (alpha) on the surface s of peripheral immunocompetent cells of young children infected,vith respi ratory syncytial virus (RSV) and influenza virus. Flow cytometric analysis revealed a significantly higher percentage of CD14+ monocytes/macrophages t hat were strongly ICAM-1-positive in the influenza group than in age-matche d controls, whereas the ICAM-1 expression levels of the RSV and control gro ups did not differ significantly. Analysis of LFA-1 alpha expression by CD3 + T lymphocytes showed a significantly higher percentage of strongly posit ive cells in the influenza group than in the age-matched controls. By contr ast, the percentage of cells that were strongly LFA-1 alpha-positive was si gnificantly lower in the RSV group than in the age-matched controls. These results suggest that no increase of adhesion molecule expression occurs in vivo in patients with RSV infection, and also that there is little activati on of peripheral blood monocytes/macrophages and T lymphocytes in young chi ldren with RSV infection.