The Human Defence System

B cell

A type of white blood cell (lymphocyte) that helps fight infection by producing antibodies. B cells can also become plasma cells or memory B cells.

T cell

A type of lymphocyte that helps defend the body by attacking infected cells or helping coordinate immune responses.

Plasma cell

A specialized B cell that produces large amounts of antibodies to fight pathogens.

Memory B cell

A B cell that “remembers” a pathogen after infection, allowing the immune system to respond faster if the pathogen returns.

antigen-presenting cell

A cell that captures pathogens and displays pieces of them (antigens) to activate T cells and start an immune response.

Lymphocyte

A type of white blood cell involved in immunity. Includes B cells and T cells.

Leukocyte

Another name for a white blood cell that helps protect the body from disease and infection.

antigen

A substance (usually on a pathogen) that triggers an immune response and causes the body to produce antibodies

anitbody

A protein made by plasma cells that attaches to antigens to help destroy pathogens.

pathogen

A disease-causing microorganism, such as bacteria, viruses, fungi, or parasites.