Biochemical features of blood cells

• The basic function and composition of blood is 8% of an adult’s body weight, with females having 4-5 litres and males having 5-6 litres.
• The temperature of blood is 38 degrees Celcius and the pH is 7.35-7.45.
• The viscosity of blood is 4.5-5.5 times as viscous as water.
• The composition of blood includes White Blood Cells (WBCs), Leucocytes, Granulocytes, Agranulocytes, Neutrophils, Lymphocytes, Eosinophils, Monocytes, and Basophils.
• Red Blood Cells (also called erythrocytes) are formed elements of blood, with a shape of a biconcave disc, a volume of 80-100 fL, and an area of about 160 μm2.
• The red blood cell membrane is about 50% protein, 40% lipid bilayer, and 10% carbohydrates that occur only on the external surface.
• The red blood cell membrane proteins include Integral Proteins such as Band-3 and Glycophorine, and Extrinsic Proteins like Spectrin, Band-4.1, and Band-4.2.
• A genetic defect in NADPH oxidase causes chronic granulomatous disease, characterized by severe, persistent, infections and formation of granulomas.
• Neutrophils and monocytes play an important role with both oxygen-independent and oxygen-dependent mechanisms for killing bacteria.
• High lysosomal enzyme activities such as myeloperoxidase and NADPH oxidase are present in neutrophils.
• The oxygen-independent mechanism involves using pH changes in phagolysosomes and lysosomal enzymes to destroy pathogens.
• The rapid consumption of molecular oxygen that accompanies formation of superoxide is referred to as the respiratory burst.
• The glycolysis and pentose phosphate pathway is very active in neutrophils.
• The oxygen-dependent system includes the enzymes, NADPH oxidase and myeloperoxidase (MPO) that work together in killing bacteria.
• Moderate oxidative phosphorylation occurs in neutrophils.
• Spherical erythrocytes that are old and cannot pass through the reticular sinusoid structure in the spleen are destroyed and disposed there.
• CD11/CD18 integrins in the cell membrane exist in neutrophils.
• After internalization of the microorganism has occurred, NADPH oxidase, located in the leukocyte cell membrane, is activated and reduces molecular oxygen from the surrounding tissue into superoxide (O2•), a free radical.
• Specific enzymes and proteins are present in neutrophils.
• Myeloperoxidase catalyzes the formation of bactericidal hypochlorous acid from peroxide and chloride ion.
• NADPH oxidase uses molecular oxygen and NADPH electrons to produce superoxide radicals, which, in turn, can be converted to peroxide by superoxide dismutase.
• Erythrocytes have no nucleus and mitochondria, and energy in the form of ATP is supplied directly from glucose metabolism.
• Band-3 protein, or anion channel, is mainly anion transporter protein of erythrocyte.
• Hereditary Elliptocytosis (HE) is a highly variable red cell membrane disorder with many clinical subtypes, it is autosomal dominant inherited.
• The defect in Hereditary Spherocytosis is a deficiency of the key membrane protein, spectrin, and to a lesser degree, a deficiency of membrane protein ankyrin and the minor membrane proteins Band 3 and Band 4.2.
• Glycophorin is a blood group antigen.
• The sodium ion inflow to erythrocytes is accelerated by abnormal proteins, normal disc-shaped cells become macro-micro spherocytic.
• Band 1 and Band 2 are Spectrin.
• There are four metabolic pathways that are essential for red cell function: Hexose monophosphate shunt pathway, Embden-Meyerhof glycolytic pathway, Luebering-Rapoport shunt, and methemoglobin reductase pathway.
• The most used test for diagnosis of Hereditary Spherocytosis is the Red Cell fragility test, also called erytrocytic osmotic resistance test, which is a simple and easy method.
• Band-7 protein, Stomatin, is a component of the cytoskeleton.
• Band 4.1 and Band 4.2 stabilize the binding between ankyrin and anion channel (Band-3).
• Spectrin molecules form a mesh-like pattern in the red cell membrane.
• Red cell Membrane Proteins are separated by SDS Polyacrylamide Gel Electrophoresis.
• Band-5 protein, Actin, is a component of the cytoskeleton.
• Hereditary Spherocytosis (HS) is characterized by the presence of spherocytes, which are the most common cause of inherited chronic hemolysis in Northern Europe.
• Hereditary Stomatocytosis is a rare hemolytic disorder, the defect is identified as a deficiency in the membrane protein, stomatin (Band 7), leading to increased water in the red cell.
• The red blood cell (RBC) is highly dependent upon glucose as its energy source, glucose is transported through RBC membrane by facilitated diffusion through glucose transporters (GLUT-1).
• The Embden-Meyerhof pathway provides 90% of the cellular ATP because red cell metabolism is essentially anaerobic.
• In normal conditions, erythrocytes behave like osmometers, according to the increasing and decreasing of osmotic pressure in medium, they swell and shrink.