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Historically, white blood cells were classified by their physical characteristics (granulocytes and agranulocytes), but this classification system is less frequently used now. Produced in the bone marrow, white blood cells defend the body against infections and disease. An excess of white blood cells is usually due to infection or inflammation.
This is a list of immune cells, also known as white blood cells, white cells, leukocytes, or leucocytes. They are cells involved in protecting the body against both infectious disease and foreign invaders .
Leukocytes can be broken into two major forms: granulocytes and non-granulocytes (monocytes and lymphocytes). Subcategories This category has the following 4 subcategories, out of 4 total.
Monocytes are a type of leukocyte or white blood cell. They are the largest type of leukocyte in blood and can differentiate into macrophages and monocyte-derived dendritic cells. As a part of the vertebrate innate immune system monocytes also influence adaptive immune responses and exert tissue repair functions.
Neutrophils are the most abundant white blood cells in the human body (approximately 10 11 are produced daily); they account for approximately 50–70% of all white blood cells (leukocytes). The stated normal range for human blood counts varies between laboratories, but a neutrophil count of 2.5–7.5 × 10 9 /L is a standard normal range.
The condition of having too few white blood cells is leukopenia, while having too many is leukocytosis. There are individual terms for the lack or overabundance of specific types of white blood cells. The number of white blood cells in circulation is commonly increased in the incidence of infection. [5]
Macrophages can express paracrine functions within organs that are specific to the function of that organ. In the testis , for example, macrophages have been shown to be able to interact with Leydig cells by secreting 25-hydroxycholesterol , an oxysterol that can be converted to testosterone by neighbouring Leydig cells. [ 15 ]
These cells also have a limited ability to participate in phagocytosis, [20] they are professional antigen-presenting cells, they regulate other immune cell functions (e.g., CD4+ T cell, dendritic cell, B cell, mast cell, neutrophil, and basophil functions), [21] they are involved in the destruction of tumor cells, [17] and they promote the ...