Reticuloendothelial system cells

Reticuloendothelial system Cells located throughout the body that can phagocytose particulate matter. 

Conventional liposomes are MLVs made of lipids having neutral or negative charge. These liposomes are large. Because of their surface characteristics they are readily cleared from blood circulation by reticuloendothelial system cells, and hence they have a short biological half-life [2]. Conventional liposomes are most conunonly used in research to investigate the entrapment of compounds and their release profiles. Moreover, they are commonly studied as model biological membranes [1]. 

In normal human subjects, some 25 % of total body iron (800-1000 mg) is present in the storage forms, mostly as ferritin. Whereas it is likely that all mammalian cell types contain some ferritin, haemosiderin in normal subjects is essentially restricted to cells of the reticuloendothelial system. Ferritin turns out to be almost universal in its distribution ferritin and ferritin-like proteins have been found in all organisms except for one or two archaebacteria. In contrast, haemosiderin has not been found to any extent outside of iron-loaded animals, except for a brief report of a phytosiderin in pea seeds (Laulhere et ah, 1989). 

Red blood cells are amongst the most numerous of the human cell lines an average healthy 70 kg male having a total of approximately 25 x cells in his 51 of blood. A typical red cell contains in excess of 600 million haemoglobin molecules which equates to a total of about 300 g of haemoglobin, an amount that is far greater than for any other protein in the body. The lack of a nucleus clearly indicates that red cells cannot divide and at the end of their life, worn out RBCs are removed by the cells of the reticuloendothelial system. Approximately 2% (5 x 1011) of the red cell number are removed and replaced by new ones each day. Haem synthesis is outlined later in this chapter and its catabolism is discussed in Chapter 6. 

Malignancies of various types— multiple myelomatosis, Waldenstrom macroglobulinemia, chronic lymphocytic leukemia, reticulum cell sarcoma, Hodgkin s disease, Burkitt s lymphoma and other malignancies of the reticuloendothelial system... 

Physiologically, body stores are maintained by extracting approximately 10% of the iron provided in a balanced diet and this corresponds to 1.5 mg each day for males and slightly more for females to compensate for pregnancy and menses. The trace element is derived from food by peptic digestion and after reduction the ferrous form crosses the enterocyte to be released at the serosal pole via the ferroportin-hepcidin mechanism to be transported, by plasma transferrin, to developing red cells in the marrow for haemoglobin synthesis. At the end of their life span effete erythrocytes are removed by the reticuloendothelial system in the spleen, bone marrow and the liver. 

Physiologically red cells are removed from circulation at the end of their lifespan by the reticuloendothelial system. This is thought to occur as the genetic machinery required to maintain intracellular mechanisms for defence from oxidative stress ceases to function and membrane integrity is lost. 

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