It is well recognized that lymphocytes and lymphopoietic tissue, as a whole, play an important role in antibody formation to antigenic stimuli whether bacterial or transplantation in origin.1 Methods known to suppress the graft rejection such as irradiation, steroids, and antimetabolites all decrease the leukocyte count, especially the lymphocyte population of the body.
Lymphocytes presumably formed in different tissues of the body (lymph nodes, spleen, thymus) are brought to the general circulation at least in part via the thoracic duct and accessory lymphatic channels. Kay commented that "presumably, lymphoid stem cells which are constantly poured from the thoracic duct into the blood stream are the active agents (for immune response)."2 Thus, creation of a thoracic duct fistula, thereby preventing the lymphocytes from gaining entrance to the venous circulation, could be utilized to decrease the lymphocyte population of the blood and result in decreasing or preventing their immunologic response.
Singh LM, Vega RE, Makin GS, Howard JM. External Thoracic Duct Fistula and Canine Renal Homograft. JAMA. 1965;191(12):1009-1011. doi:10.1001/jama.1965.03080120043011