Reference ranges for<unk> lood tests of white<unk> lood cells, comparing<unk>  amount (shown in violet) with other cells.<unk> s appear in many specific kinds of inflammatory reactions, particularly those that cause allergic symptoms.<unk> s contain anticoagulant heparin , which prevents<unk> lood from clotting too quickly. They also contain the vasodilator histamine, which promotes<unk> lood flow to tissues. They can<unk> e found in unusually high numbers at sites of ectoparasite infection, e.g., ticks. Like eosinophils,<unk> s play a role in<unk> oth parasitic infections and allergies. They are found in tissues where allergic reactions are occurring and probably contribute to the severity of these reactions.<unk> s have protein receptors on their cell surface that<unk> ind IgE, an immunoglobulin involved in macroparasite defense and allergy. It is the<unk> ound IgE antibody that confers a selective response of these cells to environmental substances, for example, pollen proteins or helminth antigens. Recent studies in mice suggest that<unk> s may also regulate the<unk> ehavior of T cells and mediate the magnitude of the secondary immune response. CD200<unk>  function is inhibited<unk> y CD200. Herpesvirus-6, herpesvirus-7, and herpesvirus-8 produce a CD200 homolog which also inhibits<unk>  function. This suggests that<unk> s may play a role in the immune response to these viruses. The role of<unk> s in the immune response to these viruses is further supported<unk> y findings that the CD200 receptor is expressed more frequently in<unk> s than in other circulating leukocytes. Secretions<unk> s arise and mature in<unk> one marrow. When activated,<unk> s degranulate to release histamine, proteoglycans (e.g. heparin and chondroitin), and proteolytic enzymes (e.g. elastase and lysophospholipase). They also secrete lipid mediators like leukotrienes (LTD-4), and several cytokines. Histamine and proteoglycans are pre-stored in the cell's granules while the other secreted substances are newly generated. Each of these substances contributes to inflammation. Recent evidence suggests that<unk> s are an important source of the cytokine, interleukin-4, perhaps more important than T cells. Interleukin-4 is considered one of the critical cytokines in the development of allergies and the production of IgE antibody<unk> y the immune system. There are other substances that can activate<unk> s to secrete which suggests that these cells have other roles in inflammation. The degranulation of<unk> s can<unk> e investigated in vitro<unk> y using flow cytometry and the so-called<unk> -activation-test <unk> AT). Especially, in the diagnosis of allergies including of drug reactions (e.g. induced<unk> y contrast medium), the<unk> AT is of great impact.<unk> asopenia (a low<unk>  count) is difficult to demonstrate as the normal<unk>  count is so low; it has<unk> een reported in association with autoimmune urticaria (a chronic itching condition).<unk> ia is also uncommon<unk> ut may<unk> e seen in some forms of leukemia or lymphoma.
Basophil
Monocyte
Prolymphocyte
Thymocyte
Podocyte
Mast cell
Dendritic cell
Natural killer cell