Changes in cell adhesion molecule expression on T cells associated with systemic virus infection.

Virus-induced changes in adhesion molecule expression on T cells were investigated to understand how antiviral effector cells migrate into infectious foci. FACS analysis revealed that after systemic infection with lymphocytic choriomeningitis virus a number of cell adhesion molecules, including VLA-4, LFA-1, and ICAM-1, are up-regulated on CD8+ cells, whereas the lymph node homing receptor MEL-14 is down-regulated during the infection; only marginal changes were observed for CD4+ cells. Basically similar but less marked results were obtained in mice infected with Pichinde virus. Further analyses showed that T cells with a changed adhesion molecule profile tended to present other cell surface markers indicating a state of cellular activation, e.g., IL-2R, and included all virus-specific CTL effectors. Regarding the physiologic significance of these changes in adhesion molecule expression, it was found that up-regulation of VLA-4 expression on splenic T cells correlated with influx of inflammatory cells into the cerebrospinal fluid of intracerebrally infected animals, and that the number of CD8+VLA-4hi cells increased from lymph nodes and spleen to blood and cerebrospinal fluid. These results support the hypothesis that up-regulation of VLA-4 is important for effector T cell homing to sites of inflammation.