Autoreactive cells as mediators of the natural defense against malignant tumors

The present paper suggests that the natural defense mechanisms against tumors are part and a logical consequence of the natural mechanisms that maintain tissue uniformity. We further suggest that biologic errors steadily are accumulated in cells with increasing age, and that the number of cells with insufficient functional capacity (aberrant cells) increases with age. Since this increasing number of aberrant cells threatens the uniformity and function of the cell population, aberrant cells must be removed in order to maintain tissue uniformity. The aberrant cells may be removed by autonomous destruction or by cytotoxic attack by autoreactive cells. Such autoreactive cells are present in the normal organism throughout life, may be suppressed by thymus-derived cells, and may be activated by immune adjuvants. We suggest from theoretic and experimental reasons that the major function of autoreactive cells is the maintenance of tissue uniformity and tissue homeostasis within a cell population.