The Immune System - An Overview

• Immunohematology is the study of blood transfusion medicine.
• Suppressor T cells slow down the process once the infection has been taken care of, acting as a sort of off-switch.
• A unit of blood is usually 450-500 mL plus 63 mL of an anticoagulant.
• The blood unit can be used as whole blood or divided into its components: plasma, platelets, red blood cells, cryoprecipitate, granulocyte concentrations.
• Cryoprecipitate is a part of the plasma that is rich in factor VIII and is used for hemophiliacs.
• The immune system recognizes self from non-self and defends the body against non-self.
• There are two types of immunity: innate and adaptive.
• The innate or natural immunity provides immediate protection.
• The innate immunity has non-specific specificity.
• The components of the innate immunity include phagocytes and other skin defenses; present before invader
• The innate immunity is directed at all pathogens or foreign particles without memory of prior exposures.
• The innate immunity is the first line of defense and includes physical barriers like unbroken skin and mucous membranes.
• The upper layer of skin is Keratinized.
• Tough protective substance in hair and nails is Keratin.
• Normal flora on the upper layer of broken skin deters foreign microorganisms.
• Secretions of the skin like sebum (oil) and lactic acid (from sweat) have antimicrobial properties.
• Earwax provides innate immunity by trapping microorganisms.
• Tears and saliva contain secretions of the immune system with lysozymes that attack some bacterial cell walls.
• Mucous provides innate immunity by trapping microorganisms.
• The second line of defense of innate immunity includes cellular and humoral response.
• The humoral response includes complement, lysozymes, interferon.
• The second line of defense of innate immunity can result in phagocytes, complement, and acute inflammatory response.
• The adaptive immunity kicks in when the body's innate defense has been overwhelmed.
• The adaptive response allows the body to accomplish recognition, remember, and respond to a certain stimulus (antigen).
• The first step of immune response is that the body must recognize self from non-self in order to know it has been invaded by something foreign.
• The body's recognition of self from non-self develops during embryonic growth and completes 4-6 months after birth.
• Macrophages, neutrophils, and mast cells signal the adaptive response.
• Tissue monocyte becomes tissue macrophage during the adaptive response.
• In relation to innate immune cells, T-lymphocytes will react with more speed comparatively in the event of an infection.
• B cells mature in the BM.
• Cytotoxic T cells pump perforin which forms pores in the cell membrane, causing apoptosis.
• Macrophages' main function is phagocytosis, which is the process of engulfing and destroying foreign substances.
• T lymphocytes make up 70-80% of the PB white blood cells.
• T lymphs can live up to 20 years.
• Once the helper T cell is activated via lock and key, it can activate B cells.
• Adaptive immunity is specific to individual pathogens or foreign particles; takes time and is more selective than innate immunity.
• Activated T cells secrete a variety of cytokines that together with specific antigens trigger activation of other T-cells (e.g. cytotoxic T cells) and B cells.
• Plasma cells make lots of specific antibodies.
• Helper T cells can be distinguished from other cells by the CD4 marker on its cells surface.
• B cells become plasma cells or effector B cells if stimulated.