ENHANCED ENDOTHELIAL-CELL ADHESION OF HUMAN CEREBROSPINAL-FLUID LYMPHOCYTES

Lymphocyte migration into a tissue depends on properties of both the l ymphocyte and the tissue's vascular endothelium. The central nervous s ystem (CNS) possesses a specialized microvasculature and lymphocytes a ppear to enter the CNS less readily than peripheral tissues. We invest igated whether those lymphocytes that interact with the CNS, as repres ented by cerebrospinal fluid (CSF)-derived lymphocytes, express adhesi ve properties distinct from peripheral blood lymphocytes (PBLs). Adhes ion of human lymphocytes to bovine endothelial cell monolayers was qua ntitated microscopically. A greater number of PBLs adhered to aortic t han to retinal endothelial cell cultures (e.g., 10.9 +/- 0.6 and 4.5 /- 0.2, respectively; P = 0.0023). Preincubation of either endothelial cell type with tumor necrosis factor-alpha (TNF-alpha) enhanced lymph ocyte adhesion. Activation of PBLs with concanavalin A or phytohemaggl utinin increased endothelial cell adhesion and the effect was additive with that of TNF-alpha. The number of CSF lymphocytes adhering to end othelial cell cultures (retinal, 67.5 +/- 9.0; aortic, 83.7 +/- 10.6) was more than 10 times the number of PBLs (retinal, 5.4 +/- 0.8; aorti c, 8.0 +/- 1.3; P < 0.0001), CSF lymphocytes did not, however, adhere preferentially to CNS-derived endothelial cell cultures. These results suggest that CSF may be enriched, compared with peripheral blood, in its content of surveillance lymphocytes, but that these cells might en ter target tissues nonspecifically.