Infections

• A pathogen is a disease-causing organism.
• An antibody is a Y-shaped specialised protein that is produced by plasma cells in response to a non-antigen.
• An antigen is any substance capable of causing a specific immune response.
• Self-antigens are large molecules produced in a person's own body that do not cause an immune response.
• Non-self antigens are foreign compounds that do trigger an immune response.