LYMPHOCYTE RECRUITMENT AND THE KINETICS OF ADHESION RECEPTOR EXPRESSION DURING THE PULMONARY IMMUNE-RESPONSE TO PARTICULATE ANTIGEN

The selectins and beta 2 integrins participate in the recruitment of n eutrophils in acute pulmonary inflammation, However, the cell adhesion receptors that mediate lymphocyte trafficking into the lung have not been defined, This study examined the relationship between cell adhesi on molecules on the pulmonary vasculature and on lymphocytes recovered from the lung during a pulmonary immune response to intratracheal (IT ) sheep red blood cells (SRBCs) in sensitized C57BL/6J mice, Silver-en hanced immunogold staining and reverse transcriptase polymerase chain reaction of lung tissues revealed sustained induction of VCAM-1, E-sel ectin, and P-selectin on the pulmonary vasculature for up to 7 days af ter IT-SRBC challenge. Neither the MECA 79 nor MECA 367 antigens were induced on the pulmonary vasculature during this period, In the periph eral blood, both CD4 and CD8 T-cell subsets showed an initial increase in P-selectin ligand expression after IT-SRBC challenge, The number o f P-selectin ligand-positive T cells in the peripheral blood fell as T cells with both P-selectin and, to a lesser extent, E-selectin ligand s accumulated in the bronchoalveolar lavage fluid, We conclude that IT -SRBC challenge in sensitized mice elicits prolonged synthesis of P-se lectin, E-selectin, and VCAM-1 by the lung vasculature as well as sele ctin Ligand synthesis by responding T cells, Furthermore, the entry of selectin-ligand-positive T cells into the circulation and their accum ulation in the bronchoalveolar lavage fluid indicates that these recep tors may contribute to T cell recruitment, Finally, VCAM-1 on the vasc ulature may also participate; however, the vascular addressins, requir ed for homing to peripheral and mucosal lymphoid organs, are not essen tial for T-cell entry into the lung following IT-SRBC challenge.