Natural history of mouse syngeneic lymphoma. Morphologic and immunologic aspects.

The morphologic changes in lymphoreticular tissues and development of antitumor immune reactions of specific pathogen-free mice injected with syngeneic lymphoma cells were sequentially analyzed. The regional (right inguinal) lymph node demonstrated mild changes indicative of immunologic response. Systemic lymph nodes revealed a moderate degree of immune response on morphologic basis. The spleen was the site of marked activity, characterized by the presence of large pyroninophilic cells and germinal centers. Foci of necrosis in the local tumor accompanied by mature lymphocytes suggested cell-mediated immune rejection. Mice developed circulating antibodies 2 days after implantation. No antibodies were demonstrated attached to fresh tumor cells. Lymphocyte cytotoxic activity was demonstrated beginning on day 4. Both cytotoxic activity and circulating antibodies were no longer detectable after the third week following tumor implantation. Tumor-bearing mice also had an impaired capacity to mount a primary immune reaction to sheep red blood cells. The spleen demonstrated a marked loss of lymphocytes and the subsequent appearance of masses of amyloid material. It is suggested that amyloidosis in lymphoreticular organs is the result of a derangement in the immune response of the host following a prolonged and sustained antigenic stimulation. It appears that in syngeneic pathogen-free mice the spleen plays the major role in immune rejection mechanisms while the draining node only plays a modest role.