What is the Immune system?

The immune system is a complex network of cells, tissues, and organs that work together to protect the body from infection and other diseases. It helps to recognize and neutralize foreign substances, such as bacteria, viruses, and toxins, that can enter the body and cause harm.

The main components of the immune system include:

1. White blood cells (leukocytes): These are specialized cells that defend the body against infection and disease. There are several types of white blood cells, including neutrophils, monocytes, and lymphocytes.
2. Lymphoid tissue: This includes the thymus, spleen, lymph nodes, and tonsils, which produce, store, and transport white blood cells.
3. Antibodies: These are proteins produced by certain white blood cells that help to neutralize foreign substances and mark them for destruction.
4. The complement system: This is a group of proteins that work together to help destroy foreign substances and remove them from the body.
5. The immune system also includes specialized organs, such as the bone marrow, which produces white blood cells, and the tonsils and adenoids, which provide a first line of defense against infection.

Overall, the immune system plays a crucial role in helping the body to fight off infection and disease, and maintaining good health.

What is Innate Immunity?

• Innate immunity is the naturally-occurring immunity generated through genetic factors and the body’s physiology.  
• Innate immunity begins at birthand continues throughout one’s life. 
• The prior exposure to pathogens is not required by the innate immunity. 
• The removal of pathogens via the natural immunity happens either in the internal organs or outwardly. 
• External defense functions as the first line of defense against pathogens and is accomplished through the biological and chemical barrier. 
• Saliva, tears mucus linings, stomach acid, and a few of the bacteria that reside in the gut function as barriers that prevent the entry of pathogens into cells of your body. 
• The second line of defense is the defense mechanisms within the immune system that is innate. 
• Different types of phagocytes function as internal barriers, stopping the proliferation and growth of pathogens in the tissues. 
• Macrophages, natural killer cells neutrophils, monocytes, mast cells and dendritic cell are examples of cells that are involved in immune system’s innate. These cells kill pathogens via their phagocytosis. They also stimulate the complement system in the body and also adaptive immunity. 
• Both internal and external mechanisms of innate immunity produce non-specific immune responses to pathogens.

The innate immune system is the body’s first line of defense against infections and other foreign substances. It provides a rapid, non-specific response to a wide variety of threats. The main barriers of the innate immune system include:

1. Skin: The skin is a physical barrier that protects the body from external threats, such as bacteria, viruses, and toxins. It also contains sweat and oil glands that produce substances that can help to inhibit the growth of microorganisms.
2. Mucous membranes: These are found in areas of the body that are exposed to the external environment, such as the nose, mouth, and respiratory and digestive tracts. Mucous membranes produce mucus, which helps to trap and remove foreign substances before they can enter the body.
3. Cilia: These are tiny, hair-like structures that line the respiratory and reproductive tracts. They move in coordinated waves to help move mucus and foreign substances out of the body.
4. Stomach acid: The acid in the stomach is highly acidic and helps to kill bacteria and other microorganisms that may be present in food or drink.
5. Saliva: Saliva contains enzymes that help to break down food and inhibit the growth of bacteria in the mouth.
6. Tears: Tears contain enzymes and other substances that help to inhibit the growth of bacteria and other microorganisms on the surface of the eyes.

Overall, the barriers of the innate immune system work together to protect the body from infection and other threats by blocking or destroying foreign substances before they can enter the body.

Types of innate immunity

1. Individual immunity

Individual immunity refers to the specific immunity that an individual develops in response to a particular infectious agent or other foreign substance. This can occur through exposure to the agent, such as through vaccination or natural infection, or through the transfer of immunity from another individual, such as through the placenta during pregnancy or through breast milk.

There are two main types of individual immunity: active immunity and passive immunity.

1. Active immunity: This occurs when the body’s immune system is stimulated to produce its own antibodies in response to an infection or vaccination. Active immunity can provide long-lasting protection against a particular infectious agent.
2. Passive immunity: This occurs when antibodies or other immune factors are transferred from one individual to another, providing temporary protection against an infectious agent. Passive immunity can be natural, such as when a mother passes immunity to her baby through the placenta or breast milk, or it can be artificially induced, such as through the administration of immune globulin.

Overall, individual immunity is important for protecting against infection and other diseases, and it can be acquired through exposure to an infectious agent or through the transfer of immunity from another individual.

2. Racial immunity

It is referred to as racial immunity when one race is resistant to a particular disease while another is susceptible to it. Again, genetic makeup, dietary habits, and climate conditions play a crucial role in determining racial immunity.

3. Species immunity

When a disease strikes only one species while another is completely immune to it, this is referred to as species immunity. For example, only humans may contract diseases like as measles, mumps, HIV, etc. These diseases cannot be transmitted to animals.

Different types of barriers are utilised by innate immunity to guard against disease. Included among these are cytokine, cellular, physiological, and physical.

Significance of innate immunity

There are several important functions of innate immunity:

1. Rapid response: The innate immune system is the body’s first line of defense and is activated immediately upon the presence of an invading pathogen or harmful substance. This rapid response helps to prevent the spread of infections and other harmful substances.
2. Physical barriers: Innate immunity includes physical barriers such as the skin and mucous membranes, which help to prevent the entry of pathogens and other harmful substances into the body.
3. Chemical barriers: The innate immune system also includes chemical barriers such as antimicrobial proteins, which help to inhibit the growth and proliferation of pathogens.
4. Detection and elimination of invaders: Cells such as neutrophils and macrophages play a key role in detecting and eliminating invading pathogens and other harmful substances.
5. Activation of the adaptive immune response: The innate immune response helps to activate the adaptive immune response, which is a more specific and long-lasting immune response that is triggered after the innate immune system has responded.

Overall, the innate immune system is important for maintaining overall health and preventing the spread of infections and other harmful substances.

Examples of innate immunity

Examples of innate immunity include:

1. Physical barriers: Physical barriers such as the skin and mucous membranes help to prevent the entry of pathogens and other harmful substances into the body.
2. Chemical barriers: Antimicrobial proteins such as lysozyme, which is found in tears and saliva, help to inhibit the growth and proliferation of pathogens.
3. Inflammatory response: The inflammatory response is an important component of the innate immune system and involves the activation of immune cells such as neutrophils and macrophages. These cells help to detect and eliminate invading pathogens and other harmful substances.
4. Fever: Fever is a response to infection or other harmful substances that is mediated by the innate immune system. Fever can help to inhibit the growth and proliferation of pathogens and can also help to stimulate the immune response.
5. Interferons: Interferons are proteins that are produced by cells in response to viral infections. They help to inhibit the growth and replication of viruses and stimulate the immune response.

What is Adaptive Immunity?

Acquired immunity, also known as adaptive immunity, is the body’s second line of defense against infections and other harmful substances. It is a specific immune response that is triggered after the innate immune system has responded. Acquired immunity is developed after exposure to an antigen, either through vaccination or through natural infection.

The immune system “learns” to recognize and respond to specific antigens, and this knowledge is retained in the form of immune memory. This allows the immune system to mount a more efficient and rapid response to future exposures to the same antigen.

There are two main types of acquired immunity: humoral immunity and cell-mediated immunity. Humoral immunity is mediated by antibodies produced by B-lymphocytes (also known as B-cells) and helps to neutralize pathogens and toxins. Cell-mediated immunity is mediated by T-lymphocytes (also known as T-cells) and involves the direct attack and elimination of infected cells.

Acquired immunity is specific to the antigen that triggered the immune response and provides long-lasting protection against future exposures to the same antigen. It is an important component of the body’s overall immune defense system and plays a crucial role in protecting against infections and other harmful substances.

Characteristics of Adaptive immunity

Adaptive immunity, also known as acquired immunity, is characterized by several key features:

1. Specificity: Adaptive immunity is specific to the antigen that triggered the immune response. This means that the immune system “learns” to recognize and respond to specific antigens, and this knowledge is retained in the form of immune memory. This allows the immune system to mount a more efficient and rapid response to future exposures to the same antigen.
2. Diversity: The immune system can develop a vast array of recognition molecules, allowing it to recognise billions of distinct antigen structures.
3. Immunologic memory: Due to immunological memory, subsequent exposure to the same antigen results in a more rapid and potent immune response. Due to immunologic memory, the secondary immune response is more rapid and robust than the primary immune response, and there is a lifelong memory against many illnesses, including measles.
4. Self/nonself recognition: Typically, the adaptive immune system responds only to foreign antigens, suggesting its capacity for self/nonself identification. Two forms of adaptive immunological responses exist: humoral or antibody-mediated immunity and cell-mediated immunity.
5. Long-lasting protection: Adaptive immunity provides long-lasting protection against future exposures to the same antigen. This is in contrast to innate immunity, which is non-specific and provides rapid but short-lived protection.
6. Activation of the immune system: Adaptive immunity involves the activation of the immune system, which leads to the production of antibodies and the development of immune memory. This is in contrast to passive immunity, which involves the transfer of antibodies or immune cells from one individual to another and does not result in the activation of the immune system.
7. Two main types: There are two main types of adaptive immunity: humoral immunity, which is mediated by antibodies produced by B-lymphocytes, and cell-mediated immunity, which is mediated by T-lymphocytes.

Overall, adaptive immunity is characterized by specificity, long-lasting protection, the activation of the immune system, and the presence of two main types: humoral immunity and cell-mediated immunity.

Types of Acquired (Adaptive) Immunity

When a pathogen enters the body, acquired immunity can be created by the host body or by the transfer of antibodies or lymphocytes into the host body.

1. Active Acquired immunity

Active acquired immunity refers to the immune response that is triggered when an individual is exposed to an antigen, either through natural infection or vaccination. During active immunity, the immune system “learns” to recognize and respond to the antigen, and this knowledge is retained in the form of immune memory. This allows the immune system to mount a more efficient and rapid response to future exposures to the same antigen.

Active immunity can be either naturally acquired or artificially acquired. Naturally acquired active immunity occurs when an individual is exposed to an antigen through natural infection with a pathogen. Artificially acquired active immunity occurs when an individual is intentionally exposed to an antigen through vaccination.

Both types of active immunity involve the activation of the body’s immune system, which leads to the production of antibodies and the development of immune memory. Active immunity provides long-lasting protection against future exposures to the same antigen.

2. Passive Acquired immunity

Passive acquired immunity refers to the immune protection that is provided by the transfer of antibodies or immune cells from one individual to another. Passive immunity is temporary and does not result in the development of immune memory.

There are two main types of passive acquired immunity:

1. Passive natural immunity: Passive natural immunity occurs when an individual receives antibodies from their mother through the placenta or through breast milk. This type of immunity provides temporary protection to the newborn or infant against certain infections.
2. Passive artificial immunity: Passive artificial immunity occurs when an individual is intentionally given antibodies or immune cells from another individual or from an animal. This can be done through the administration of immune globulin, which contains high levels of pre-formed antibodies, or through the transfer of immune cells such as T-lymphocytes. Passive artificial immunity is often used to provide temporary protection against infections or as a treatment for certain immune disorders.

Passive acquired immunity is not as long-lasting as active immunity, but it can provide rapid protection against infections and other harmful substances.

Significance of Acquired (Adaptive) Immunity

Acquired immunity, also known as adaptive immunity, is an important component of the body’s overall immune defense system and plays a crucial role in protecting against infections and other harmful substances. Some of the key benefits and importance of acquired immunity include:

1. Specificity: Acquired immunity is specific to the antigen that triggered the immune response. This means that the immune system “learns” to recognize and respond to specific antigens, and this knowledge is retained in the form of immune memory. This allows the immune system to mount a more efficient and rapid response to future exposures to the same antigen.
2. Long-lasting protection: Acquired immunity provides long-lasting protection against future exposures to the same antigen. This is in contrast to innate immunity, which is non-specific and provides rapid but short-lived protection.
3. Protection against infections: Acquired immunity plays a crucial role in protecting against infections caused by pathogens such as bacteria, viruses, and parasites. It does this through the production of antibodies and the activation of immune cells such as T-lymphocytes, which help to eliminate infected cells and inhibit the growth and proliferation of pathogens.
4. Vaccination: Acquired immunity can be artificially induced through vaccination, which involves the administration of a weakened or inactivated form of a pathogen. This triggers the immune system to produce antibodies and develop immune memory, providing protection against future infections with the same pathogen. Vaccination is an important public health measure that helps to reduce the incidence and spread of infectious diseases.

Overall, acquired immunity is an important component of the body’s immune defense system and plays a crucial role in protecting against infections and other harmful substances.

Examples of Acquired (Adaptive) Immunity

Examples of acquired immunity, also known as adaptive immunity, include:

1. Natural infection: Acquired immunity can be naturally acquired through exposure to an antigen through natural infection with a pathogen. For example, an individual who becomes infected with the measles virus will develop immunity to the virus after recovering from the infection.
2. Vaccination: Acquired immunity can also be artificially induced through vaccination, which involves the administration of a weakened or inactivated form of a pathogen. This triggers the immune system to produce antibodies and develop immune memory, providing protection against future infections with the same pathogen. Examples of vaccines include the measles, mumps, and rubella (MMR) vaccine, the influenza vaccine, and the hepatitis B vaccine.
3. Immune globulin: Passive artificial immunity can be provided through the administration of immune globulin, which contains high levels of pre-formed antibodies. Immune globulin can be given to provide temporary protection against infections or as a treatment for certain immune disorders.
4. T-lymphocyte transfer: Passive artificial immunity can also be provided through the transfer of immune cells such as T-lymphocytes. This can be done to provide temporary protection against infections or as a treatment for certain immune disorders.

Overall, acquired immunity can be naturally acquired through natural infection or artificially induced through vaccination or the transfer of antibodies or immune cells. It provides specific, long-lasting protection against infections and other harmful substances.

Similarities between innate and acquired immunity

Innate immunity and acquired immunity are two different types of immune responses that play different roles in the body’s overall immune defense system. However, there are also some similarities between the two:

1. Both innate and acquired immunity involve the activation of immune cells such as neutrophils, macrophages, and T-lymphocytes, which help to detect and eliminate invading pathogens and other harmful substances.
2. Both innate and acquired immunity involve the production of proteins and other substances that help to inhibit the growth and proliferation of pathogens. Examples of these substances include antimicrobial proteins, antibodies, and interferons.
3. Both innate and acquired immunity involve the activation of the inflammatory response, which helps to protect the body against infections and other harmful substances.
4. Both innate and acquired immunity are important for maintaining overall health and preventing the spread of infections and other harmful substances.

Overall, while innate immunity and acquired immunity are two different types of immune responses that play different roles in the body’s immune defense system, they both work together to protect the body against infections and other harmful substances.

Difference between innate and acquired immunity

Characteristics	Innate Immunity	Adaptive Immunity
Definition	This refers to the natural-occurring immunity that is triggered by the genetic components and the body’s physiology.	Adaptive immune is a term used to describe an acquired immunity that is dependent on T cells and B cells. It is also characterized by an immune memory.
Alternative Names	Innate Immunity is referred to by its natural Immunity.	It is also known as acquired immunity.
Specificity	Innate immunity generates a non-specific immune response.	Adaptive immunity generates a specific immune response.
Presence	Innate immunity is always present in the body.	Adaptive immunity only occurs in response to exposure to an external factor.
Response	Since innate immunity provides the first line defense against the pathogens, it generates a rapid response.	Adaptive immunity is delayed 5-6 days.
Components	Plasma proteins, phagocytes, physical and chemical barriers are the components of the innate immunity.	Humoral and cell-mediated immunity are the components of the adaptive immunity.
Physical and Chemical Barriers	Temperature, pH, skin, and mucous membranes are the barriers of the innate immunity.	Lymph nodes, spleen, and lymphoid tissues are the barriers of the adaptive immunity.
Memory Cells	Innate immunity does not develop memory cells.	Adaptive immunity develops memory cells.
Diversity	Innate immunity possesses a less diversity.	Adaptive immunity possesses a higher diversity.
Potency	Innate immunity is less potent.	Adaptive immunity exhibits a higher potency.
Allergic Reactions	Innate immunity does not produce allergic reactions.	Adaptive immunity develops allergic reactions; immediate and delayed hypersensitivity.
Activation of the Complement System	Innate immunity activates the complement system through the alternative and lectin pathway.	Adaptive immunity activates the complement system through the classical pathway.
Time Span	Once developed for a particular pathogen, the innate immunity remains throughout the lifetime.	Adaptive immunity can last for the lifetime or for a short period of time.
Inheritance	Innate immunity is inheritable.	Adaptive immunity is not inheritable.
Cells involved	Dendritic leukocyte, Natural killer cells, Mast cell, Granulocytes/ Macrophages, Basophils, etc.	Killer CD8+ T-cells, Helper CD4+ T-cells, B-cells, Antigen presenting cells, etc.
Molecules involved	Cytokines, Complement cells, Interferon, Acute phase reactants/ proteins	Antibodies, Cytokines
Receptors	Germline encoded No somatic rearrangement Non-clonal distribution	Encoded in gene segments Somatic rearrangement necessary Clonal distribution
Action time	Immediate effector activation	Delayed effector activation
Order of defence	It is the first line of defense of immune system	Action against pathogens that are able to evade or overcome innate immune defense
Subsequent exposure	Immune response does not get alter on repeated exposure .	Immune response get improves with subsequent exposure.
Allery or	None	Immediate and delay
Reason behind immune evasion	Caused by pathogenic virulence	Caused by mutation of the recognized antigen
Development	Evolutionary, older and is found in both vertebrates and invertebrates.	Adaptive immunity system has been developed recently and is found only in the vertebrates.
Diversity	Limited	High
Examples	The redness and swelling caused by white blood cells around a wound is an example of an innate immune response.	Vaccination against a virus is an example of adaptive immunity.

Key Difference between innate and acquired immunity

Innate immunity and acquired immunity are two different types of immune responses that play different roles in the body’s overall immune defense system. Some of the key differences between innate and acquired immunity include:

1. Timing: Innate immunity is the body’s first line of defense and is activated immediately upon the presence of an invading pathogen or harmful substance. Acquired immunity is the body’s second line of defense and is triggered after the innate immune system has responded.
2. Specificity: Innate immunity is non-specific and provides rapid but short-lived protection against infections and other harmful substances. Acquired immunity is specific to the antigen that triggered the immune response and provides long-lasting protection against future exposures to the same antigen.
3. Memory: Innate immunity does not involve the development of immune memory. Acquired immunity involves the development of immune memory, which allows the immune system to mount a more efficient and rapid response to future exposures to the same antigen.
4. Components: The components of the innate immune system include physical barriers such as the skin and mucous membranes, chemical barriers such as antimicrobial proteins, and cells such as neutrophils and macrophages. The components of the acquired immune system include antibodies produced by B-lymphocytes and T-lymphocytes, which play a key role in the immune response.

Overall, innate immunity and acquired immunity are two different types of immune responses that work together to protect the body against infections and other harmful substances. Innate immunity provides rapid protection, while acquired immunity provides specific, long-lasting protection.

References

• https://pediaa.com/difference-between-innate-and-adaptive-immunity/
• https://microbiologyinfo.com/difference-between-innate-and-adaptive-immunity/