Specialized Cells and Molecules of the Immune System
Specialized Cells and Molecules of the Immune System
Lymphocytes
Small white blood cells found in all organs and tissues. There are 2 principal types: B lymphocytes (B cells), which mature in the bone marrow, and T lymphocytes (T cells), which mature in the thymus.
B cells
These lymphocytes are responsible for the production of antibodies, an important part of the immune response.
T cells
These lymphocytes include killer (cytotoxic) T cells, which detect and kill cells that are abnormal (such as cancer cells), and helper T cells, which help other lymphocytes mount an immune response.
Antigens
Any substances that can induce an immune response.
Antigen-presenting cells
Specialized cells that engulf antigens and process them so that they can be recognized by lymphocytes.
Neutrophils
All-purpose scavenger cells that ingest and destroy antigens and cell debris.
Macrophages
White blood cells that stimulate healing and remove antigens, injured cells, and neutrophils from tissue.
Eosinophils
White blood cells that ingest bacteria and other foreign cells, participate in allergic reactions, and help destroy cancer cells.
Mast cells
Cells that release histamine and other substances involved in allergic reactions.
Cytokines
The immune system’s messengers, typically small proteins, which help regulate an immune response by delivering signals from one cell to another.
Antibodies
Also called immunoglobulins, antibodies are proteins produced by B cells that interact with specific antigens. They can form immune complexes, label antigens for removal by other cells, or block the ability of a virus to enter its target cell.
