High concentration of bilirubin in post-nodal lymph associated with red blood cell catabolism in lymph nodes of the sheep.
Qualitative and quantitative analysis of post-nodal lymph of the sheep has shown that the distinct yellow colour of this fluid pool is due to the presence of relatively large amounts of bilirubin. In efferent lymph from thepopliteal, prefemoral, prescapular, renal and intestinal lymph nodes total bilirubin concentrations were 3-8 times higher than the corresponding concentrations in blood plasma. In contrast the total bilirubin concentrations in afferent lymph from the lower leg and kidney were less than the corresponding concentrations in blood plasma. Histological examination of several popliteal and mesenteric lymph nodes revealed the presence of free iron and bilirubin in the cytoplasm of cells located near the lymphatic sinuses of the node. In addition, the concentration of bilirubin in efferent lymph from the popliteal node was observed to increase following an induced rise in the number of red blood cells reaching the node by way of the afferent lymphatic duct. These latter observations suggest that the bilirubin in post-nodal lymph is associated with the catabolism of extravascular red cells by reticulo-endothelial cells within the lymph nodes.
D000418:Albumins / Q000032:analysis; D000818:Animals; D001663:Bilirubin / Q000032:analysis* / Q000096:biosynthesis; D004905:Erythrocyte Aging; D004906:Erythrocyte Count; D005260:Female; D006418:Heme / Q000378:metabolism; D006461:Hemolysis; D008196:Lymph / Q000032:analysis* / Q000166:cytology; D008198:Lymph Nodes / Q000502:physiology*; D008264:Macrophages / Q000378:metabolism; D008297:Male; D012756:Sheep
D000418:Albumins; D006418:Heme; D001663:Bilirubin