LYMPHOCYTE RECRUITMENT FOLLOWING SPINAL-CORD INJURY IN MICE IS ALTERED BY PRIOR VIRAL EXPOSURE

The inflammatory response induced by mechanical lesion of the spinal c ord is known to include the recruitment of neutrophils and macrophages , while the involvement of lymphocytes has been largely ignored. We ha ve studied the pattern of lymphocyte recruitment following partial tra nsection of the mouse spinal cord. Using immunohistochemical technique s, all three types of lymphocytes (CD4-positive T-cells, CD8-positive T-cells and B-cells) were found in the vicinity of the lesion site wit hin hours and persisted for up to 7 days. There was a predominance of B-lymphocytes during the first 3 days. A second, late phase of cell in filtration, dominated by CD8-positive T-lymphocytes, occurred in mice that had been raised in a conventional breeding unit and had acquired antibody titres to a common murine virus (mouse hepatitis virus). In c ontrast, mice kept in specific pathogen-free facilities did not show t his late-phase response. These findings suggest a possible role for ly mphocytes in secondary tissue loss, local demyelination, scar formatio n, cytokine-mediated inflammatory responses or trophic processes. They also provide evidence that a virus infection can significantly enhanc e the reaction of T-cells to a spinal cord lesion.