MIGRATION OF PHAGOCYTIC-CELLS INTO THE RAT AFFERENT HEPATIC LYMPH SYSTEM

Blood-borne foreign particulates are primarily removed from the circul ation in the liver by ''resident'' macrophages or Kupffer cells. To ex amine phagocytosis and the movement of phagocytic cells, foreign parti culates (1.3 mu m diameter fluorescent latex beads or fixed bacteria) were injected aseptically into the portal vein of Sprague-Dawley rats and, after 1-7 days, liver, afferent hepatic lymph, and hepatic and me senteric lymph nodes were sampled. Intracellular beads and bacteria we re detected by transmission electron microscopy in hepatic sinusoids, parenchyma and lymph nodes. Phagocytic cells containing 50 to 100 bead s were frequently observed. Intracellular fluorescent particles were d emonstrated by flow cytometry in afferent hepatic lymph and in hepatic but not mesenteric lymph nodes. These findings are consistent with ph agocytic cell migration from the liver via afferent lymph to hepatic l ymph nodes. Viruses, bacteria and cancer cells may also translocate fr om the bloodstream into the hepatic lymph system via this pathway.