What response does the immune system have to antigens from malignant cells?

The immune system's response to antigens from malignant cells is referred to as immunologic surveillance. This concept describes the body's ability to detect and eliminate cancer cells that present abnormal antigens. Through this mechanism, the immune system continuously monitors for changes in cells that could indicate tumorigenesis. It recognizes these tumor-associated antigens (TAAs) and mounts a response to eliminate cells displaying these potentially harmful markers.

In immunologic surveillance, T cells, particularly cytotoxic T lymphocytes, play a crucial role by identifying and destroying cells that express abnormal antigens that arise from mutations or the altered expression of genes in malignant cells. Natural killer (NK) cells also contribute to this process by recognizing and killing cells that are downregulating or losing major histocompatibility complex (MHC) class I molecules, which often occurs in cancerous cells.

Understanding immunologic surveillance is critical in cancer treatment, as therapies that enhance the immune system's response to these antigens—such as immune checkpoint inhibitors or cancer vaccines—aim to strengthen this natural defense against malignancy and improve patient outcomes.