Immune Response

The body’s response to foreign substances entering it, for example bacteria. The body identifies antigens molecules molecules (eg proteins, sugars) belonging to the invading organism. The immune system, for example, can identify proteins on the virus’s envelope and act against them by producing antibodies. In cancer, cancer cells can express very high and abnormal levels of a particular molecule, which is also called antigen (although it is not foreign, it is part of the body). The immune system can identify this aberration and initiate an immune response. For example, breast cancer cells may express higher amounts than the normal HER2 molecule, which stimulates the immune system to respond to the HER2 overexpressing cells. Cancer cells develop various mechanisms that help them avoid the immune system.