Perspectives for antitumor therapy based on the recognition mechanism by which macrophages identify undesirable...

Though immunotherapy appears to be a promising therapy for tumors with antigenicity, it may have only a limited usefulness, because tumor cells do not reveal tumor-specific antigens. In contrast, macrophages may be able to distinguish and remove tumor cells because they can recognize and remove both undesirable foreign and native substances, and can do this independently of MHC or antigenicity. For the development of a new antitumor therapy based on the molecular mechanism to enhance the elimination of tumor cells, it is considered important to clarify the recognition mechanism of undesirable foreign and native substances by macrophages. Advanced data in this field of research have been rapidly accumulated recently. The macrophage recognition system for undesirable foreign and native substances is based on multiple receptors which bind to various kinds of foreign substances, suggesting a complicated mechanism. Much of this system is still undescribed and further study is needed. Even in the most advanced research areas (the recognition system of bacteria and their products by macrophages), the data still suggest the existence of unknown receptors. We therefore believe that research into the nature of these unknown receptors can provide information which may be used to develop novel antitumor therapies in the future.