Role of the regional lymph node in cancer metastasis.

At an early phase of tumor growth, T-cell responses, i.e. the proliferation of T cells and the generation of cytotoxic T cells or killer-augmenting T cells are induced in the regional lymph node depending upon the immunological properties of the tumor cells. A small number of tumor cells seems to be rejected in the regional lymph node in situ. A progressive tumor induces suppressor activity in the regional node. Suppressor cells facilitate tumor growth and lead to lymphatic metastasis. Thus, the regional lymph node operates only as a temporary barrier to tumor growth. Experimental studies have demonstrated that eradication of the suppressor cells and effective immunization, or both, lead to tumor rejection by augmenting the immunological activity of the regional lymph node.