THIRD LINE OF DEFENCE
The third line of defence is the last resort, if it fails then the outcome is death. There are two main comportments, the B cells and the T cells which work together to recognise and fend of antigens. With the presence of MHC class markers, T cells and B cells are able to recognise self and non-self cells. On finding a foreign antigen B cells trigger a cascade of events where they multiply into plasma membranes that are specific to an antigen. There are two different types of responses, humoral/anti-body mediated and cell mediated.