Intralymphatic Introduction of Radioactive Colloids into the Lymph Nodes

With the possibility in mind that it might be desirable to convey certain materials for therapeutic purposes directly to lymph nodes, preliminary experiments have been carried out on the dog's hind leg. The behavior of a lymph node toward foreign particles injected directly into the lymph trunk has received very little study. Drinker, Field, and Ward (1934) observed efficient filtration of red blood cells and bacteria by a single popliteal node and by a regional lymphatic system in the dog (1). Walker (1950) injected yttrium hydroxy citrate colloids in a trunk afferent to the popliteal node of the rabbit and then measured filtration or retention by the popliteal and pelvic nodes (2). His experiments were based on single injections with very small (0.05 to 0.20 ml.) volumes of fluid, and the measurements of radioactivity were made on nodes dissected one to nine days after injection. The first node in the filtering system retained a major portion of the injected colloid; secondary or tertiary nodes usually contained far less and never as much as the primary node. The retention of the colloid in the nodes was related to the size of the colloid particles and to the fluid volume. Of two preparations, that with the larger particles was retained in greater amount in the primary node and in lesser amount in the secondary nodes. Retention was greatest when the fluid volume was least. Retention of a particulate material within the lymph node depends upon several factors : (a) temporary filling of the node channels by the flow of fluid into and through the node; (b) phagocytosis of particles by reticuloendothelial cells of the node; (c) mechanical trapping of large particles in the finer structure of the node ; (d) temporary adherence of the particle to node structures by a physicochemical process. Disappearance of the particles from a node would be dependent upon: (a) flow of lymph or other solutions through the node, mechanically washing out the particulate matter ; (b) passage of material by extra-lymphatic paths into capillaries or into adjacent tissue; (c) release of particles by phagocytes; (d) movement of phagocytic cells still containing the engulfed particles from the node. In order for intralymphatically injected radioactive colloids to be effective in treating diseases of the lymph nodes, a more balanced distribution of the colloids than found by Walker would be desirable. Accordingly, the behavior of the popliteal and pelvic nodes of the dog in relation to the direct lymphatic injection of radioactive colloidal gold2 was brought under study. Technic A No. 10 polyethylene catheter was placed in the lower leg lymph trunk of a mongrel dog under Nembutal anesthesia. The trunk selected was several centimeters peripheral or afferent to the popliteal node.