Lymphotoxin-beta receptor immune interaction promotes tumor growth by inducing angiogenesis.

Growth of solid fibrosarcoma tumors in mice was inhibited by the release of a solublelymphotoxin-beta receptor inhibitor (LTbetaR-immunoglobulin fusion protein) from the tumor cells. Tumor growth arrest in mice deficient in the ligand LTalpha1beta2 demonstrated the requirement for activation of the LTbetaR on the tumor cells by host cell-derived LTalpha1beta2. Activation of the LTbetaR resulted in enhanced release of macrophage inflammatory protein-2. Blocked angiogenesis was revealed in LTbetaR inhibitor-producing tumor nodules by immunohistochemistry and in vivo microscopy. The growth arrest of LTbetaR inhibitor-producing fibrosarcomas was overcome by forced MIP-2 expression in the tumor cells. Thus, LTbetaR activation on tumor cells by activated host lymphocytes can initiate a novel proangiogenic pathway leading to organized tumor tissue development.