Blood Components and Blood Groups (I-16.3.1.1) 2024-2025 PDF

Blood components and blood groups (I-16.3.1.1) 2024/2025 Safaa Sharrah Lecturer of Physiology SOM  Objectives By the end of this lecture, the student should be able to: ▪ Describe the different types of blood cells and understand their function(s) ▪ Give a brief account of...

Blood components and blood groups (I-16.3.1.1) 2024/2025 Safaa Sharrah Lecturer of Physiology SOM  Objectives By the end of this lecture, the student should be able to: ▪ Describe the different types of blood cells and understand their function(s) ▪ Give a brief account of the ABO blood group system and its significance. ▪ Understand haemolytic disease of the new-born ▪ Brief understanding of transfusion reactions ▪ Understand Issues in managing massive blood loss Date : / 1/ 2018  Blood * The red fluid contained in the blood vessels, pumped around the body by the heart. * has an average volume of 5 liters in woman and 5.5 liters in men.  BLOOD consists of: Fluid part Cellular elements = Plasma Red blood cells "Erythrocytes" White blood cells "Leucocytes" Largely made in the liver Platelets "Thrombocytes" -Clotting Factors -Albumin All made in the bone marrow -Immunoglobulin Reticulocytes All blood cells are formed from a common stem cell by a process referred to as HAEMOPOIESIS, which occurs in the bone marrow.  FUNCTIONS OF BLOOD A) Transport function: Respiratory function (O2 and CO2 ) Nutritive function: absorbed substances from GIT to tissues. Excretory function: non-volatile metabolites to the kidneys. Regulatory function: hormones. B) Regulation of body temperature C) Hemostatic function: Blood clots in injured vessel to prevent further blood loss. D) Defensive function (WBC)  PLASMA the fluid portion of blood. Volume: 3,500 ml in 70 Kg man Colour: Yellow. pH: 7.4 Composition Water: 90% Plasma proteins Inorganic constituents (Na+, Cl- , HCO3- , K+, Ca2+, Mg+ and others).  PLASMA PROTEINS do not exit through the narrow pores in the capillary walls. Total protein in blood is 7g/dl. Albumin Globulin fraction (Immunoglobines= Antibodies) Fibrinogen (Clotting factors)  Red Blood Corpuscles (Erythrocytes) The most abundant cells in the blood. *Shape: Non-nucleated, flat, disc-shaped biconcave discs. The biconcave shape ➔a larger surface area for diffusion of oxygen and carbon dioxide across the membrane than a spherical cell of the same volume. *Number: 5 million/mm3 * Life span of a RBC in the circulation is on the average 120 days. The RBC membrane: * Semipermeable. *Contains the agglutinogens to determine the blood groups. *keeps Hb inside ➔prevents its loss in urine. RBCs content: -Hemoglobin -Water 60% - inorganic and organic substances (enzymes) - No nucleus, organelles or ribosomes (They were extracted during the cells development to make room for more hemoglobin) HEMOGLOBIN [Hb] Red pigment , appears red when combined with O2 and bluish when deoxygenated. The Hb molecule consists of: 1. The globin portion: protein of 4 highly folded polypeptide chains, forming 2 pairs. Each pair is one type of polypeptide chains. 2. The heme moiety: 4 iron-containing protoporphyrin bound to one of the polypeptides. Each hemoglobin molecule can pick up 4 O2 molecules. Functions of Hemoglobin (=functions of RBCs): Carriage of O2 Helps in carriage of CO2 Hb is an important buffer in blood. The normal hemoglobin content of blood is 16g/dl in men and 14g/dl in women (all in RBC). Hemolysis means the lysis of RBCs with liberation of Hb, and its appearance in plasma. FATE OF RBCs Old RBCs are taken up by spleen Hb molecule is broken into heme and globin. BLOOD GROUPS 1) ABO system-classic blood groups: discovered by Landsteiner in 1901 ❖ The membranes of human RBCs contain agglutinogens A- and B-agglutinogens (glycoprotein) ❖ Agglutinogens present in many tissues (epithelial and endothelial cells), and secretions (salivary glands, kidney, liver, lungs) ❖4 major groups: A, B, AB and O. ❖Other clinically important groups (Duffy, Kell, Kidd and S) Antibodies against red cell agglutinogens (agglutinins): Present in plasma. Naturally occurring antibodies to the antigens that the person does not express Agglutinins against A and B- Frequency in UK: 42% 8% 47% 3% agglutinogens [anti-A (α) and anti-B (β)] occur 3-6 months from birth Antibodies are IgM and can agglutinate and activate complement  Antigen-antibody reaction (=agglutination) occurs when antigen and its corresponding antibody come together. When bloods are mismatched ➔ the agglutinins attach themselves to the RBCs. Because agglutinins have many binding sites, a single agglutinin can attach to different red cells at the same time ➔the cells clump, plug small blood vessels ➔destroyed by phagocytic cells , and the reticuloendothelial system, releasing Hb  2) Rhesus (Rh) system: named for the first studied in Rhesus monkey not been found in tissues other than red cells. "D" is the most important antigenic component. Rh-positive ➔ agglutinogen D, found in 85 – 90% of population. Rh-negative ➔ the individual has no D-antigen and forms the anti-D agglutinin when injected with D+ve cells. The anti-D-antibodies (agglutinin) are not naturally present in Rh-negative individuals. Rh System D - codes for D antigen on RBC and is dominant d - codes for no antigen and is recessive ➔ dd = no D antigen = RhD negative ➔ DD or Dd = D antigen present = RhD positive  Anti-D Antibodies - Implications 1. Future transfusions - patient must have RhD negative blood in future (otherwise anti-D would react with RhD positive blood ➔ causes delayed haemolytic transfusion reaction - anaemia; high bilirubin; jaundice) 2. HDN = haemolytic disease of the new-born Erythroblastosis Fetalis: (Hemolytic disease of the New-born) due to Rh-incompatibility between mother and fetus blood. if RhD -ve mother has anti-D - and in next pregnancy, her foetus is RhD +ve ➔mother’s IgG anti-D antibodies can cross placenta ➔ causes haemolysis of fetal red cells ➔ if severe: hydrops fetalis, death Treatment: Exchange transfusion, to replace the newborn’s blood with Rh –ve blood. Prevention targets the mother  Prevention of Hemolytic Disease of Newborn To prevent sensitization of an Rh-negative mother, she is given a single dose of anti-Rh antibodies in the first 48 hours after delivery starting from first delivery. Also, be careful when giving blood transfusion to females (even very young girls) who may be Rh-negative and are transfused with Rh-positive blood.  History of Blood Transfusion 1829 - James Blundell’s Gravitator Aveling’s transfusion - 1873 Early human to human transfusion Fatal No understanding of blood groups No cross matching of donor and recipient 1900 Karl Landsteiner, an Austrian physician, discovers the first three human blood groups, A, B, and C (now known as O) Landsteiner receives the Nobel Prize for Medicine for this discovery in 1930 Modern transfusion Safer but fatalities still occur due to wrong blood transfused to the wrong patient BLOOD TRANSFUSION The process of transferring blood or blood-based products from person into the circulatory system of another person Indications: 1. hemorrhage 2. In severe anemia (to restore Hb level). 3. People suffering from sickle-cell disease may require frequent blood transfusions. 4. In bleeding attacks due to disturbances in clotting mechanisms or platelet function (transfusion of clotting factors). 5. In erythroblastosis fetalis.  Whole Blood Red Cells Platelets Plasma fresh frozen plasma Cryoprecipitate albumin Coagulation Factors 1)Red Blood Cells 3ml/kg increases the Hb by 1g About 280ml in a unit Expect an increase of > 1g/dl Hb/unit of Packed cells in adults – depending on size of adult and the donor unit Stored at 4oC Can be stored for up to 35 days  2) Platelets 1 pool from 4 donors (= standard adult dose) or from 1 donor by apheresis (cell separator machine) Store at 22oC (Room temp) - constantly agitated Shelf life 7 days only - (risk of bacterial infection) Need to know blood group, no crossmatch needed 3) Fresh Frozen Plasma (FFP) 1 unit from 1 donor (300ml) can get small packs for children Stored at -30oC Shelf life 1 year Must thaw approximately 20-30 mins before use (if too hot proteins cook) – Give ASAP - within 1h or else coagulation factors degenerate Dose 12-15ml/kg = usually 2 or 3 units Need to know blood group – no X-match, just choose same group  4) Cryoprecipitate From frozen plasma thawed at 4-8oC overnight residue remains Contains fibrinogen and factor VIII Same as FFP - store at -30oC for 1 year Standard dose = from 10 donors (5 in a pack) Indications: If massive bleeding and fibrinogen very low Hypofibrigoneaenemia Transfusion Reactions: (= Effects of incompatible blood transfusion) When recipients plasma has agglutinins against the donor's red cells, the cells agglutinate Immune Non Immune  A) Immune Transfusion Reactions Acute - Acute haemolytic transfusion reactions - Anaphylaxis Delayed - Delayed Haemolytic transfusion reactions - Post transfusion purpura - Neonatal immune disorders including Rh disease of the newborn Acute Transfusion reaction Agglutinated RBCs form clumps blocking capillaries ➔pain and tightness of the chest immediately. The clumps are hemolyzed, releasing Hb into plasma ➔ jaundice. ➔Free Hb is liberated into the plasma. ➔renal tubular damage and renal failure and may be death. Histamine release causing vasodilatation, resulting in hypotension. B) Non Immune Transfusion Reactions Infective : bacterial, viral, prion Iron Overload: - 200mg Fe per unit of Packed RBC - Major cause of morbidity and mortality in people with transfusion dependent diseases Dangers of Blood Transfusion: I- Immediate: Hemolytic reactions. Mechanical overloading of the circulation in cardiac diseases. Hyperkalemia: due to its release from old hemolysed cells ➔sudden death. Citrate intoxication with massive transfusion due to excessive citrate infusion ➔hypocalcemia and acidosis. Bacterial contamination: specially with cold-growing gram- negative bacilli ➔shock associated with fever. Prolonged storage at room temperature (>4 hours) encourages the growth of contaminating bacteria. II- Delayed: Transmission of diseases e.g. AIDs, hepatitis, jaundice, malaria and syphilis. Special Considerations Age of blood – Young blood lasts longer, less cation leakage Specific phenotype requests usually (Rh and Kell) – For multiply transfused e.g. sickle and thalassaemia Irradiated – Depressed T cell function e.g post BMT (bone marrow transplantation), di George, Hodgkin lymphoma, certain drugs e.g. fludarabine CMV negative – Pregnancy and IUT – Other requirements for this differ between institutions. Others e.g. Washed, plasma depleted, T antigen negative  References: Guyton & Hall: Textbook Of Medical Physiology. Lippincotte Illustrated Reviews Physiology Further information http://www.transfusionguidelines.org.uk/ http://hospital.blood.co.uk/ http://www.bcshguidelines.com/ http://www.shotuk.org/ For transfusion reactions and haemolytic anaemias a good haematology textbook e.g. Hoffbrand