BLOOD-TO-LYMPH MIGRATION OF SMALL LYMPHOCYTES THROUGH THE LIVER OF THE SHEEP

The process of lymphocyte migration is required for the systemic disse mination of immunological memory and immune surveillance. We report he re experiments to quantitate the normal traffic of lymphocytes that oc curs from blood to lymph through the liver and hepatic node in the she ep. Comparisons were made with known lymphocyte homing pools. Individu al afferent hepatic lymphatics had cell outputs of 1.4 +/- 0.1 x 10(6) cells/hr, suggesting that the total combined lymphocyte output from t he liver was no greater than about 1 x 10(7) cells/hr. The lymphocyte output in efferent hepatic lymph was 6.2 +/- 0.4 x 10(7) cells/hr, com parable to the cell outputs recorded from other lymph nodes of similar size. When the specificity of lymphocytes homing through the liver or hepatic node was examined, we found similarities to both the peripher al lymph node and intestinal lymph node homing patterns. Migration int o afferent hepatic lymph was found to be different from that into inte stinal or subcutaneous efferent lymph, and the kinetics of migration i nto hepatic afferent lymph was faster than that observed into efferent compartments. Intravenously injected endotoxin was found to alter the normal lymph how through the liver tissue and the hepatic node; it ap peared to enhance the migration of macrophages out of the liver by way of the afferent lymph. These studies suggest unique features of lymph ocyte traffic through the liver and the need for further experiments o n hepatic lymphocyte traffic, particularly in pathological states with substantial mononuclear cell infiltration.