[Protein deficiency, host defense and natural anti-tumor immunity]

Natural immuneffector cells, namely natural killer cells and monocyte/macrophages, have become in recent years an important part of theory and practice of immunotherapy. This is especially the case for therapy of malignant tumors with biological response modifiers (BRMs). Many BRMs increase cytotoxicity against tumor cells and cell numbers of natural immuneffector cells. Protein depletion on the other hand, which often is part of malignant diseases, results in well known negative effects on acquired and specific immunity. The data which are presented here show that depressions of natural immuneffector cells in terms of cytotoxicity and cell numbers also occur after protein depletion. The same is true for their pool, the bone marrow. The potentials of BRM therapy are considerably decreased. Host defense mechanisms in normal and protein depleted nutritional status, immunological tumor defense and BRM therapy are presented in the survey.