Neutrophils, circulating

Figure 2. (1) Neutrophils circulating passively in blood capillary. (2) Chemoattractants may be detected by the circulating neutrophils, by the endothelial cells lining the lumen, or both in order that the neutrophils become adhesive. This adhesion is mediated by selectins, a group of cell surface proteins. Neutrophils roll on the surface of the endothelial cells and then actively locomote seeking out spaces between the endothelial cells. (3) The adhesive neutrophils begin to squeeze between endothelial cells. (4) Cells move through the extracellular matrix towards the site of infection. Here adhesion is low and may not be necessary for locomotion. (5) At the site of infection, neutrophils become trapped by increased adhesion where they phagocytose bacteria and liberate the contents of their granules. After Lackie (1982,1986).

Neutropenia is an abnormally reduced number of neutrophils circulating in peripheral blood. Although exact definitions of neutropenia often vary, an absolute neutrophil count (ANC) of fewer than 1000 cells/mm indicates a reduction sufficient to predispose patients to infection. The ANC is the sum of the absolute numbers of both mature neutrophils (polymorphonuclear cells [PMNs], also called polys or segs) and immature neutrophils (bands). The absolute number of PMNs and bands is determined by dividing the percentage of these cells (obtained from the white blood cell [WBC] differential) by 100 and then multiplying the quotient obtained by the total number of WBCs. 

Neutropenia— An abnormally reduced number of neutrophils circulating in peripheral blood although exact definitions of neutropenia often vary, an absolute neutrophil count of < 1000 ceUs/mm indicates a reduction sufficient to predispose patients to infection. 

Niu, X., Smith, C.W., Kubes, P., 1994. Intracellular oxidative stress induced by nitric oxide synthesis inhibition increases endothelial cell adhesion to neutrophils. Circulation Research 74, 1133-1140. 

In the very early phases of the acute inflammatory response most of the cells invading the damaged area are polymorphonuclear neutrophils, also denoted as PMNs, which serve as initial line of defense and source of proinflammatory cytokines. These cells, which usually live for 4-5 days, circulate in the blood until they are attracted by chemokines into injured tissues. Whereas physical injury does not recruit many neutrophils, infections with bacteria or fungi elicit a striking neutrophil response. The characteristic pus of a bacterial abscess is composed mainly of apoptotic (apoptosis) and necrotic PMNs. Emigration of neutrophils from the blood starts with a process denoted as margination where neutrophils come to lie at the periphery of flowing blood cells and adhere to endothelial cells (Fig. 1). L-Selectin is expressed... 

Melanocortin peptides have been proposed as potent modulators of many pathologies including inflammatory (asthma, arthritis) and cardiovascular disease. They have been shown to be directed against resident cells within tissue such as macrophages, endothelial cells and also circulating leukocytes (neutrophils and lymphocytes). Therefore harnessing their therapeutic potential could lead to the development of novel therapeutics. 

Cardiovascular disease affects 2.7 million British people and is a major cause of mortality with circulating neutrophils being proposed as contributing factors in ischaemic damage, though damage can still occur in vitro in the absence of blood. Melanocortins have... 

Neutropenia is a drop in the number of circulating leukocytes, especially neutrophils. It can be induced by a variety of drugs. Treatment with cytotoxic antineo-plastic drags usually results in severe neutropenia, which can be treated with colony-stimulating factors (G-CSF, GM-CSF). 

Suratt BT, Petty JM, Young SK, Malcolm KC, Lieber JG, Nick JA, Gonzalo JA, Henson PM, Worthen GS (2004) Role of the CXCR4/SDF-1 chemokine axis in circulating neutrophil homeostasis. Blood 104 565-571... 

Some forms of invasive candidiasis are dominated by deep organ infection and may never be detected by blood cultures. Chronic disseminated candidiasis or hepatosplenic candidiasis is a unique form of candidemia seen after recovery from neutropenia. Candidemia during the period of neutropenia may be initially localized to the portal circulation with dissemination to contiguous organs. After recovery of neutrophils, an inflammatory response is seen against areas of focal infection in the liver and spleen. This inflammatory response produces abdominal pain that is associated with... 

Hematopoiesis is defined as the development and maturation of blood cells and their precursors. In utero, hematopoiesis may occur in the liver, spleen, and bone marrow. However, after birth, it occurs exclusively in the bone marrow. All blood cells are generated from a common hematopoietic precursor, or stem cell. These stem cells are self-renewing and pluripotent and thus are able to commit to any one of the different lines of maturation that give rise to platelet-producing megakaryocytes, lymphoid, erythroid, and myeloid cells. The myeloid cell line produces monocytes, basophils, neutrophils, and eosinophils, whereas the lymphoid stem cell differentiates to form circulating B and T lymphocytes. In contrast to the ordered development of normal cells, the development of leukemia seems to represent an arrest in differentiation at an early phase in the continuum of stem cell to mature cell.1... 

There have been significant advances in the treatment of CML. The success of therapy depends in part on the clinical phase of the disease. Nearly all patients with CML are treated initially with imatinib. Hydroxyurea may be used after diagnosis to rapidly reduce high white blood cell (WBC) counts and to prevent complications associated with large numbers of circulating neutrophils. Imatinib also can reduce peripheral WBC counts over... 

---