Antigens, pathogens and allergens

Immune systems

the body system that helps resist infection and disease through specialised cells and proteins

pathogens

agents that cause diseases in their hosts

Antigen

molecules or parts of a molecule that stimulate an immune response through the adaptive immune response

Self-antigens

recognised by self-receptors as part of the same body, usually tolerated by the immune system

non-self antigens

do not belong to the bodys own cells, can be identified as invaders and attacked by immune system

Plasma membrane of immune cells

carries self-antigens that identify the cell as safe, cell surface receptors for self antigens and foreign antigens

Major histocompatibility complex (MHC)

receptor proteins on the surface of cells that identify self

MHC-I

found on all nucleated cells of the body, identify as self

MCH-II

found on specific white blood cells involved in adaptive immune response

Cellular pathogen

disease causing agent made of cells that can reproduce independently of host

non-cellular pathogen

have the ability to cause disease but are unable to reproduce independently of host cells and lack metabolic activity