Immunoregulation of T-lymphocyte proliferative activity by alveolar macrophages from mice bearing Lewis lung carcinoma tumors

The immune regulatory abilities of alveolar macrophages from C57B1/6 mice bearing a metastatic variant of Lewis lung carcinoma were determined. During early stages of tumor development, or before tumors metastasized to the lungs, alveolar macrophages did not affect or slightly enhanced T-lymphocyte proliferation; as tumor growth progressed, or following tumor metastasis, alveolar macrophages suppressed the T-cell response. Macrophage suppressor activity was probably not mediated by their production of PGE, since macrophages of tumor-bearing mice secreted less 2 PGE than did macrophages of normal mice. Normal alveolar 2 macrophages or macrophages preincubated in tumor cell supernatant for a short period stimulated T-cell blastogenesis and secreted PGE during in vitro culture. However, with 2 longer exposure to tumor cell supernatant, alveolar macrophages lost the capacity to augment T-cell proliferation and secreted less PGE 2.Ball State UniversityMuncie, IN 47306