A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include T cells, B cells, and innate lymphoid cells, of which natural killer cells are an important subtype. They are the main type of cell found in lymph, which prompted the name "lymphocyte". Lymphocytes make up between 18% and 42% of circulating white blood cells.
Scanning electron micrograph of a human T cell
A stained lymphocyte surrounded by red blood cells viewed using a light microscope
A scanning electron microscope image of normal circulating human blood showing red blood cells, several types of white blood cells including lymphocytes, a monocyte, a neutrophil and many small disc-shaped platelets
Several lymphocytes seen collected around a tuberculous granuloma
White blood cells, also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. White blood cells include three main subtypes: granulocytes, lymphocytes and monocytes.
A scanning electron microscope image of normal circulating human blood. In addition to the irregularly shaped leukocytes, both red blood cells and many small disc-shaped platelets are visible.
Neutrophil engulfing anthrax bacteria
