Immunogenicity of Lewis lung carcinoma in C57BL/6 mice. I. Tumor-associated antigen(s) in peripheral blood, thymus and spleen of tumor-bearing mice.

Some aspects of the immunogenicity of the Lewis lung (3LL) carcinoma in C57BL/6 mice are reported. Immediately after i.m. tumor transplant, and for approximately 24 h, tumor antigens were found in the blood stream. They were observed again on the 5th-6th day, when circulating tumor cells could also be noticed. Soluble immune complexes were detected in the blood sera of tumor-bearing mice from the 11th day, indicating that the host had reacted to the neoplastic antigen stimulation with immunoglobulin synthesis. Furthermore, tumor antigens were observed on some circulating lymphocytes, as well as in the thymus and in the spleen. In spleen sections, atypical mitoses also showed the presence of tumor cells. We obtained the in vitro binding of 3LL-antigens, present in 3 M KCl-solubilized extracts, to normal T lymphocytes prepared from healthy C57BL/6 mice. The possibility that circulating T lymphocytes aspecifically bind tumor antigens, carrying them to the thymus, is discussed.