Natural and Acquired Immunity
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This document summarizes the key differences between natural (innate) immunity and acquired (adaptive) immunity. Natural immunity is inborn and provides non-specific protection against pathogens through physical and chemical barriers like skin and mucous membranes. It also includes phagocytic cells that engulf and destroy pathogens. Acquired immunity develops over time after exposure to specific pathogens and antigens. It produces targeted immune responses through antibodies and T cells that provide long-lasting, pathogen-specific protection. The document compares the mechanisms, characteristics, components and responses of natural versus acquired immunity.
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Natural and Acquired Immunity
- 1. NATURAL AND ACQUIRED IMMUNITY PRESENTED BY: STEPHANIE D. BORRES BSED SCI 2-2A
- 2. PAGE 01 1. Introduction 2.Types of Immunity 2.1 Natural or Innate Immunity 2.1.1 Mechanism of Innate Immunity 2.1.2 Types of Innate Immunity 2.2 Acquired or Adaptive Immunity 2.2.1 Types of Acquired Immunity 2.2.2 Mechanism of Active Immunity 3. Characteristics of Innate and Acquired Immunity Table of Contents
- 3. PAGE 03 PAGE 02 Types of Immunity 1. Natural or Innate Immunity 2. Acquired or Adaptive Immunity Immunity is derived from Latin word “immunis” which means free from burden. In this case burden refers to disease caused by microorganisms or their toxic products. Therefore Immunity is defined as the state of resistance or in susceptibility to disease caused by particular microorganisms or their toxic products. Introduction Natural or Innate Immunity Immunity with which an individual is born is called innate or natural immunity Mechanism of Natural Immunity • Anatomical barrier • Physicochemical barrier • Phagocytic barrier or Phagocytosis • Inflammatory barrier or Inflammation
- 4. PAGE 03 PAGE 02 1. Anatomical barrier Skin and mucus membrane: •Skin consists of two distinct layer; a thin outer layer called epidermis and thick inner layer called dermis. • Skin provides first line of defense by preventing entry of microorganisms. •Below skin, the mucus membrane prevents the entry of microorganism to the body. And also it secrets mucus that entraps microorganisms.
- 5. PAGE 03 PAGE 02 2. Physicochemical barrier • Physiological conditions of body such as normal body temperature, normal body pH etc., provides immunity. Some species are resistant to certain disease simply because of their higher body temperature. Similarly, body pH also provides immunity. • Chemical barriers include various antimicrobial chemicals found in body fluids. 3. Phagocytic barrier or Phagocytosis Phagocytosis is an important defense mechanism of host to provide immunity. Most of the bacteria that enter into host are killed by phagocytic cells such as Neutrophils, monocytes and macrophages.
- 7. PAGE 03 PAGE 02 3. Phagocytic barrier or Phagocytosis Killing Mechanism of phagocytosis: Killing of ingested bacteria during phagocytosis occur by two different mechanism 1.Oxygen dependent mechanism 2.Oxygen independent mechanism NADPH reduces molecular O2 to produce various toxic metabolic products such as Hydroxyl free radical, H2O2 and superoxide ions that kill ingested bacteria. This process is also known as respiratory burst. It is the major mechanism of killing of ingested bacteria during phagocytosis. 2. Oxygen independent mechanism: •In this mechanism, ingested bacteria are killed by hydrolytic and digestive enzymes of lysozyme. 1. Oxygen dependent mechanism: During phagocytosis, phagocytic cell increases uptake of O2. At the same time rate of pentose phosphate pathway increases to generate more NADPH.
- 8. PAGE 03 PAGE 02 4. Inflammatory barrier or Inflammation Inflammation is an important defense mechanism of host to prevent infection. It is induced in response to tissue damage caused by microorganism, toxins or by mechanical means. Main aim of inflammation is to prevent spread of injected microorganism or toxin from site of injection and kill them on spot by phagocytosis. Characteristics of inflammation: 1.Rubor: redness 2.Tumor: swelling 3.Calor: heat 4.Dolor: pain 5.Functio laesa: loss of function Steps of inflammatory response
- 9. PAGE 03 PAGE 02 Types of Natural Immunity 1. Species Immunity • If one species is resistant to certain infection and the other species is susceptible to the same infection then it is called as Species Immunity. 2. Racial Immunity • If one race is susceptible while other race is resistant to same infection, then it is called Racial Immunity. 3. Individual Immunity • If one individual of certain race or cast is resistant while other individuals of same race or cast are susceptible to certain infection, then it is called as Individual Immunity
- 10. PAGE 03 PAGE 02 Acquired or Developed Immunity • Immunity which is developed later in life after microbial infection in host is called as Acquired or developed immunity. • Components of acquired immunity such as Antibodies and T- cells are specific to particular microorganism. Therefore acquired immunity is also known as Specific Immunity. Types of Acquired Immunity 1. Active Immunity 2. Passive Immunity If host itself produces antibodies, it is called Active Immunity.
- 11. PAGE 03 PAGE 02 If host does not produce antibodies itself but antibodies produced in other host provides immunity, than it is known as Passive immunity Mechanism of Active Immunity Primary immune response takes place when the host is attacked by certain microbes for first time.The antibodies start to generate after certain period as the binding of an antigen with its particular antibody is very specific. Secondary immune response occurs when an individual is being attacked by the same antigen subsequently. It is a rapid process. Acquired active immune response takes two distinct forms- humoral and cell mediatedresponse.
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- 13. PAGE 03 PAGE 02 Characteristics Natural Immunity Acquired Immunity 1.Presence Natural immunity is something already present in the body. Acquired immunity is created in response to exposure to a foreign substance. 2. Specificity Non-Specific Non-Specific 3. Response Fights any foreign invader Fights any foreign invader 4. Response Rapid Slow (1-2 weeks) 5. Potency Limited and Lower potency High potency Characteristic of Natural and Acquired Immunity Characteristics Natural Immunity Acquired Immunity 6. Time span Once activated against a specific type of antigen, the immunity remains throughout the life. The span of developed immunity can be lifelong or short. 7. Inheritance Innate type of immunity is generally inherited from parents and passed to offspring. Adaptive immunity is not passed from the parents to offspring, hence it cannot be inherited.
- 14. PAGE 03 PAGE 02 Characteristics Natural Immunity Acquired Immunity 8. Memory Cannot react with equal potency upon repeated exposure to the same pathogen. Adaptive system can remember the specific pathogens which have encountered before. 9. Presence Present at birth Develops during a person’s lifetime and can be short-lived. 10. Allergic Reaction None Immediate and Delay hypersensitivity Characteristics Natural Immunity Acquired Immunity 11. Used Against For microbes Microbes and non- microbial substances called antigens 12. Memory No memory Long term memory 13. Diversity Limited High 14. Speed Faster response Slower response 15. Complement system activation Alternative and lectin pathways Classical pathway
- 15. PAGE 03 PAGE 02 Characteristics Natural Immunity Acquired Immunity 16. Anatomic and physiological barriers Skin, Mucous membranes, Temp, pH, chemicals, etc. Lymph nodes, spleen, mucosal associated lymphoid tissue. 17.Composition The innate immune system is composed of physical and chemical barriers, phagocytic leukocytes, dendritic cells, natural killer cells, and plasma proteins. Adaptive immune system is composed of B cells and T cells. Characteristics Natural immunity Acquired Immunity Development Evolutionary, older and is found in both vertebrates and invertebrates. Acquired immunity system has been developed recently and is found only in the vertebrates. Example White blood cells fighting bacteria, causing redness and swelling, when you have a cut. Chickenpox vaccination so that we don’t get chickenpox because adaptive immunity system has remembered the foreign body.
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