MUCOSAL T-CELLS RECOVERED FROM MICE AFTER INFECTION WITH RESPIRATORY SYNCYTIAL VIRUS DISPLAY A MEMORY ACTIVATION PHENOTYPE

Pgp-1 expression was studied as a marker of memory/activation on systemic and mucosal T cells of BALB/c and C578L/6 mice after infection with respiratory syncytial virus (RSV), using two-color dual fluorescence flow cytometry employing anti-L3T4 (CD4), anti-Ly2 (CD8), and anti-Pgp-1 (CD44) monoclonal antibodies. Pgp-1 was expressed in relatively low densities on T cells of C57BL/6 mice, allowing differentiation of a dual population of Pgp-1(10) and Pgp-1(hi) T cells after antigenic stimulation in vivo. On the contrary, T cells of BALB/c mice were uniformely Pgp-1(hi), making this mouse strain less suitable for studies with this marker. In blood and spleen consistently more CD8(+) than CD4(+) T cells were Pgp-1(hi), while in BAL more CD4(+) than CD8(+) T cells were Pgp-1(hi). After primary but not after secondary infection, CD4(+) Pgp-1(hi) T cells increased significantly in the blood and spleen. After secondary infection both CD4(+) Pgp-1(hi) and CD8(+) Pgp-1(hi) T cells increased in the BAL. It is hypothesized that after primary infection systemic RSV-specific T cells acquire an activation/memory phenotype as characterized by an enhanced expression of Pgp-1, resulting in a faster and stronger influx of these cells in the lungs after secondary infection.