Immune reactivity of lymphoid tissues adjacent to carcinoma of the ascending colon

The immunologic reactivity of lymphoid tissues neighboring carcinoma of the right colon was studied in 9 patients by the lymphocyte blastogenic response method, stimulation with phytohemagglutinin, pokeweed mitogen, streptolysin O, 10 ⁶ allogeneic leukocytes irradiated with 4,000 roentgens of foreign tissue antigens, and 10 ⁴ to 10 ⁶ irradiated autochthonous tumor cells in half log dose intervals. The various lymphoid tissues varied in their nonspecific responses to mitogens and antigens and in their specific responses to autochthonous tumor cells. These different responses probably reflect different bone marrow derived and thymus dependent cell subpopulations among these tissues and, in some instances, an immunosuppressive effect exerted by the tumor.