How a Healthy Immune System Works
In a healthy body the immune system can go unnoticed in its duties and functions. In a healthy body all cells should have Major histocompatibility complex (MHC) Class I markers on their external surface. These tell the immune system that they are self cells and not to attack them. However pathogens and antigens don’t have these specialised markers and this lack of MHC markers alters the immune system to remove this pathogen/antigen from the body. Because of the lack of MHC markers non-specific cells known as macrophages will engulf the pathogen/antigen and once ingested will be exposed to lysosomes which release digestive enzymes that break down the pathogen/antigen. In some cases this may not be enough and an antigenic fragment is cut from the pathogen/antigen and displayed on the Class II MHC markers on the external surface of the cell, this is known as antigen presentation. This fragment is then collected by a T-helper cell and presented to an immature B cell. Once the fragment has been read by the B cell it will form a B plasma cell and B memory cell. The B memory cell will be stored in case the same antigen is presented; the B plasma cell however will produce antibodies specifically designed to fight off the antigen.