Cells of the Immune System

In this section we will consider the different cells that play a role in the immune system.

Leucocytes, also known as white blood cells, are immune cells that circulate within the blood and lymphatic system. There are 5 main types: neutrophils, monocytes, eosinophils, basophils and lymphocytes. We will begin with a basic overview of these general types, followed by more detailed articles considering their production, role and subtypes.

Phagocytes are a type of white blood cell that use phagocytosis to engulf bacteria, foreign particles, and dying cells to protect the body. They bind to pathogens and internalise them in a phagosome, which acidifies and fuses with lysosomes in order to destroy the contents.

They are a key component of the innate immune system. There are three main groups of phagocytes: monocytes and macrophages, granulocytes, and dendritic cells, all of which have a slightly different function in the body.

We will then consider B and T cells.

The B lymphocyte (B cell) is one of the most important cells of the body. They form a part of the adaptive immune response by producing antibodies and presenting antigens to T cells. Once activated they will either mature into plasma cells or memory B cells.

T cells (also called T lymphocytes) are one of the major components of the adaptive immune system. Their roles include directly killing infected host cells, activating other immune cells, producing cytokines and regulating the immune response.