Blood Groups & WBCs PDF

# Blood Groups ## Introduction * **RBC surfaces** are marked by genetically determined antigens, called **agglutinogens**. * **Plasma** usually contains antibodies called **agglutinins** against the missed antigens. * There are two important systems that classify blood groups: * ABO sy...

# Blood Groups ## Introduction * **RBC surfaces** are marked by genetically determined antigens, called **agglutinogens**. * **Plasma** usually contains antibodies called **agglutinins** against the missed antigens. * There are two important systems that classify blood groups: * ABO system * RH system * The ABO and Rhesus (Rh) systems of antigens are of major clinical importance as they are associated with transfusion reactions when mismatched. ## ABO System * In this system, there are two antigens, A and B. * Classified into four groups of blood: * **RBCs** with A antigen = Type A blood group * **RBCs** with B antigen = Type B blood group * **RBCs** with neither antigen = Type O blood group * **RBCs** with both antigens = Type AB blood group * With ABO, a person makes antibodies (agglutinins; IgM) against agglutinogens they do NOT have on their RBCs. ### ABO System Diagram This diagram shows the different blood types and their corresponding antigens and antibodies: | Blood Type | Surface antigen | Antibodies | | :---------- | :---------------- | :------------ | | Type A | A | Anti-B | | Type B | B | Anti-A | | Type AB | A and B | None | | Type O | None | Anti-A and Anti-B | ## Rh System * This system contains many antigens. * The most common antigen is D antigen. * It is inherited by a dominant gene. * **Rh factor (D antigen)** was first discovered in the blood of Rhesus monkeys. * Rh factors are only detectable on RBCs. * Classified into two groups: * **RBCs** with D antigen = Rh+ * **RBCs** without D antigen = Rh- ### Rh System Diagram This diagram shows the difference between Rh+ and Rh- blood types: | Blood Type | Antigen | | :---------- | :------- | | RhD +ve | D | | RhD -ve | None | ## Anti-D Antibodies * Normal plasma contains no **anti-Rh (anti-D)** antibodies. * **Anti-Rh antibodies (IgG)** are not spontaneously formed, but develop only in Rh- blood type and only when exposed to the antigen. * from a transfusion of Rh+ blood * during a pregnancy with a positive blood type fetus ## Rh System Classification | Blood Group | RH+Ve | RH-Ve | | :---------------- | :----- | :----- | | % of population | 85% | 15% | | Ag (agglutinogen) | D | - | | Ab (agglutinin) | - | Normally not present | | genotype | DD,Dd | dd | ## ABO and RH Systems | BLOOD GROUP | A | B | AB | O | | :----------- | :---- | :---- | :---- | :---- | | % of population | 40-41% | 9-10% | 3-5% | 45-47% | | Ag (agglutinogen) | A | B | AB | - | | Ab (agglutinin) | B | A | - | Anti A, Anti B | | genotype | AA,AO | BB,BO | AB | OO | | Rh Factor | Present or Absent (A+ or A-) | Present or Absent (B+ or B-) | Present or Absent (AB+ or AB-) | Present or Absent (O+ or O-) | ## Differences Between ABO and RH Systems | | ABO SYSTEM | RH SYSTEM | | :-------------- | :-------------- | :-------------- | | Type of Abs | IgM type | IgG type | | in the plasma | Normally present | Normally do not present (need exposure) | | Name of agglutinins (antibodies) | Anti A and Anti B | Anti D | | Time of production | 6-8 months after birth | Need long time and massive exposure | | Abs crossing placenta | Does not cross | Cross | ## Erythroblastosis Fetalis <start_of_image>plasia of new baby, characterized by progressive agglutination and hemolysis of a baby’s RBCs. This can occur when: 1. The mother is Rh-negative. 2. The baby is Rh-positive (having inherited the trait from their father). 3. During birth, there is a leakage of the baby’s red blood cells into the mother’s circulation. 4. This stimulates the mother’s immune system to develop anti-D antibodies (IgG class) against the D antigen. 5. In the second child, due to pregnancy with RH+ fetus, there is a hemolytic disease of the newborn. This causes hemolysis of the fetal RBCs which leads to anemia and jaundice. ### Erythroblastosis Fetalis Diagram This diagram shows the process of **hemolytic disease of the newborn:** * **a:** the mother has Rh- blood type, and the baby has Rh+ blood type. * **b:** during the first pregnancy, the baby’s blood cells can leak into the mother’s circulation. This causes the mother to develop anti-Rh antibodies. * **c:** during the second pregnancy, the mother’s anti-Rh antibodies can cross the placenta and attack the baby's red blood cells. ### Prevention and Treatment * Shortly after each birth, the mother should be injected with anti-D antibodies within 48 hours. These antibodies destroy any Rh+ fetal cells. * Usually, females with Rh-Ve blood should avoid blood transfusions with Rh+Ve blood. * **Treatment of the baby**: * If severe, they should be treated with an exchange transfusion. * Replace the baby's blood with Rh-ve RBCs (several times). ### N.B. * The first baby may be affected if the mother was sensitized before pregnancy, e.g., an abortion. ## Importance of Blood Group Determination 1. Blood transfusion 2. Erythroblastosis fetalis 3. Medico-legal importance (a negative test is sure, a positive test is not conclusive). ## Blood Transfusion Reaction * A blood transfusion reaction occurs between the donor RBCs' Ags and the recipient's plasma Abs. * The reason for the reaction is because the plasma part of the donor blood is immediately diluted by all the plasma of the recipient. * **Universal donor**: blood group (O-ve) can give blood to all other groups (it contains no Ags). * **Universal recipient**: blood group (AB+ve) can receive blood from all other groups (it contains no Abs). ### Blood Transfusion Reactions Diagram This diagram shows the cross-reactions between the ABO blood types: * When incompatible blood types are mixed, the donor RBCs are attacked by the recipient's antibodies. * This causes agglutination (clumping) and hemolysis (destruction) of the red blood cells. ### Example of an Incompatible Transfusion This diagram shows what happens when a person with type A blood receives a transfusion of type B blood: * The patient has anti-B antibodies in their plasma. * When type B blood is introduced, these antibodies attach to the B antigens on the donor's red blood cells. * This causes agglutination and hemolysis. ## Precautions Before a Blood Transfusion 1. **Tests for compatibility**: * Blood grouping (ABO and RH systems) * Cross-matching test 2. **Tests for blood-borne diseases**: Hepatitis, AIDS, or HIV 3. **Blood should be fresh and not anemic** (Hb NORMAL). ## Cross-Matching Test * **Major test**: mix the donor's RBCs with the recipient's plasma. * **Minor test**: mix the recipient's RBCs with the donor's plasma. * The **importance of a cross-matching test** is to avoid minor incompatibilities resulting from subgroups of the ABO system and antigens. ## Indication for a Blood Transfusion 1. To restore whole blood during hemorrhage. 2. To restore individual components of blood when there is a deficiency, such as platelets, WBCs, RBCs, plasma protein, or clotting factors. ## Complications of Blood Transfusion 1. **Complications due to incompatibility**: * Agglutination of RBCs causes destruction and release of contents * Hemolysis (jaundice) * Increased plasma viscosity * Precipitation in the kidney's renal tubules (acute renal failure) * Increased osmotic pressure of the blood (bilirubin) * Histamine release (allergy) * Arrhythmias 2. **Complications of blood-borne diseases**: hepatitis, AIDS # White Blood Cells (Leukocytes) ## Introduction * There are five types of white blood cells: neutrophils, eosinophils, basophils, monocytes, and lymphocytes. * The total count is 4000-11000/3mm. * **Granulocytes** and **monocytes** are formed in bone marrow. * **Lymphocytes** and **plasma cells** are formed in lymphatic tissue. ## Leukocyte Life Span * **Granulocytes**: 4-8 hours in the blood and 5 days in the tissues. * **Monocytes**: 10-20 hours in the blood and a long time in the tissues (months). * **Lymphocytes**: few hours in the blood and a long time in the tissues (weeks or months). ## Leukocyte Diagram This diagram shows the different types of white blood cells and their origins: ``` BLOOD CELLS _ / \ / \ / \ Blood Lymphoid Stem.coll Stem coll |_ | _ |/ \ | _ | / \ | | \ | |_ _ | |/ \ | |/ \ | |_| |_ |Erythrocytes Platelets Lymphoblast |_ | _ |/ \ | _ | / \ | | \ | |_ _ | |/ \ | |/ \ | |_| |_ | Basophil Neutrophil Eosinophil T Lymphocyte Blymphocyte | ``` ## Types of Leukocytes **Types of leukocytes are categorized as either granular or non-granular**: * **Granular leukocytes**: * Contain granules in their cytoplasm. * Types: neutrophils, eosinophils, basophils. * **Non-granular leukocytes**: * No granules in their cytoplasm. * Types: lymphocytes, monocytes. ### White Blood Cells Diagram This diagram shows the different types of white blood cells under a microscope: * Neutrophil * Eosinophil * Basophil * Lymphocyte * Monocyte # Neutrophils (Microphages) * They form about 60% of total WBCs. * Their surface membrane contains receptors for IgG. * **Function**: potent phagocytes that attack and destroy invading bacteria and foreign substances through six mechanisms: * **Margination**: neutrophils adhere to the walls of capillaries. * **Diapedesis**: neutrophils squeeze through capillary walls and enter tissue. * **Ameboid movement**: neutrophils move using pseudopodia (foot-like extensions) * **Chemotaxis**: neutrophils move towards the source of a chemical. * **Phagocytosis**: neutrophils engulf and destroy bacteria. ## Diagram of Neutrophil Mechanisms This diagram shows neutrophils invading bacteria using the mechanisms listed above: * A capillary with neutrophils circulating. * Neutrophils moving toward injured tissue through chemotaxis and diapedesis. # Eosinophils * They form 3% of total WBCs. * Their surface membrane contains receptors for IgG, IgM, and IgE. * **Function**: * Weak phagocytes. * Defense against parasites by diapedesis, ameboid movement, and chemotaxis. * Increase in parasitic infections. * Moderate allergic reactions by preventing spread of local inflammation. * Detoxify the inflammation-inducing substances released by mast cells and basophils. * Phagocytose and destroy Ag-Ab complexes. # Basophils * They form 1% of total WBCs. * Their surface membrane contains receptors for IgE. * **Function**: * Synthesize and liberate heparin. * Play an important role in allergic reaction. * Ag-Ab reaction stimulates basophils and mast cells to release histamine, bradykinin, serotonin, and lysosomal enzymes. * Cause local vascular and tissue reactions that cause allergic manifestations. # Monocytes (Macrophages) * They form 6% of total WBCs. * **Function**: * Phagocytosis * Help the function of B and T lymphocytes by presenting antigens to them. * Release chemical substances that increase the inflammatory reaction and the immune response to invading organisms. ### Differences Between Microphages and Macrophages | | Microphages (Neutrophils) | Macrophages (Monocytes) | | :-------------- | :----------------------- | :------------------------ | | Size | Small | Large | | Phagocytosis | Engulf 5-20 bacteria | Engulf up to 100 bacteria | | Power | Less powerful | More powerful | # Variations in Leukocyte Count * **Leukocytosis**: an increase in WBC count above 11,000/mm3. * **Leucopenia**: a decrease in WBC count below 4,000/mm3. * **Leukemia**: a greatly increased number of abnormal WBCs in the blood. * **Agranulocytosis**: a decrease in WBCs due to bone marrow failure. # Tissue Macrophage System (Reticuloendothelial System.) * Macrophages are present in tissues: liver, spleen, lymph nodes, lungs, and skin. * There are **free macrophages** in the tissues and **fixed macrophages** attached to the specific tissues. ### Types of Fixed Macrophages * **Kupffer cells**: in the liver * **Alveolar macrophages**: in the lungs * **Histocytes**: in the skin * **Osteoclasts**: in the bone * **Microglia**: in the brain * **Mesangial cells**: in the kidney # Inflammation * **Definition**: secondary changes that occur after infections, trauma, heat, or chemical injury. * **Steps of inflammation**: * **Local capillaries vasodilate**, causing redness. * **Capillary permeability increases**, causing edema. * **Clotting occurs in tissue spaces**, stopping spreading. * These changes are caused by inflammatory substances released from destroyed cells, including histamine, serotonin, and bradykinin. ## Response to Inflammation * **Tissue macrophages** are the first defense line (within 1 hour). * **Neutrophils** are the second line of defense (within a few hours). * **Monocyte macrophages** are the third line of defense (after 12 hours.)