IMMUNITY -SYLLABUS AS PER INC

a) Types of immunity – innate and discussions.
hypersensitivity acquired.autoimmunity and

b) Immunization schedule. immunizing agents Immunoprophylaxis (vaccines, sera etc.)

c) Hypersensitivity and autoimmunity.

d) Principles and uses of serological
tests

Immunity (Immunity against disease):-

     “Immunity is defined as the resistance of the body towards the harmful effects caused by the pathogenic organism and other toxic factors” 

•  (Immunity is the resistance exhibited by the Host against the conditions caused by the micro organism and its products (toxins))

Immunity(Immunity):-

• Immunity is defined as the ability of the body to recognize, destroy and eliminate antigenic material (bacteria, virus, proteins) foreign to its own.
• (Immunity is the ability of the host to recognize, destroy and eliminate antigenic material (bacteria, virus, proteins) foreign to its own. 
• Protection against infectious disease is the result of an immune response. It is a reaction against a foreign antigen.

Types of immunity

1) Innate immunity

      Innate or Native immunity is a genetic trait that a person inherits, and is not affected by previous contact with a micro-organism or immunization. When it provides resistance to infection in general, it is called non-specific, and when it provides resistance to a single pathogen, it is called specific.  & This type of immunity is found at the species, racial, and individual levels.

(i)Species immunity

• Species immunity is when almost all members of a species are immune to a pathogen. The mechanism of this immunity is not fully understood, but it is believed to be due to physiological and biochemical differences between different host species tissues.
• Which determines the cultivation of the pathogen.
• In Pasteur’s anthrax experiments on frogs, the most   This was previously observed in frogs, which were naturally resistant to the disease.
• But when they were kept at a temperature of 25 c to 35 c, some of them were found to be susceptible to anthrax.

(ii) Racial immunity (hereditary)

• Different races within a species have different susceptibility to the same or generalized infection. This is known as racial immunity.
•  Immunity against anthrax in Algerian sheep is an example of this.
•  But at present it can be developed to some extent, in some parts of Africa, people have resistance to plasmodium falciparum.

(iii) Individual  immunity (Individual immunity)

• In innate immunity, the difference seen among different individuals of the same race is called individual immunity.
• Individual immunity depends on factors such as age, hormonal influence and Nutrition is a factor,

2) Acquired immunity

• When a person acquires resistance to a micro-organism during his life, it is called Acquired immunity or Adaptive immunity. Thus it is distinguished from innate immunity.

There are two types of acquired immunity.

• (1) Active immunity
•  (2) Passive immunity

(i) Active immunity

•A person is infected with a pathogenic organism or its toxin, resulting in immunity.

•The body itself produces antibodies to fight the infection.

• Once antibodies are developed, the person becomes immune to the same infection again.

(ii) Passive immunity (Passive immunity )

• Antibodies produced in an individual  Passive immunity is when a person is protected against a disease by transferring it (Ready made) to another person. 
• In other words, the body does not produce antibodies. But depends on readymade antibodies. Passive immunity comes in the following ways.
• Injection of antisera. Eg. ATS (for protection against tetanus)
• Injection of gamma-globulin.
• Maternal immunity – antibodies are transferred from the mother to the fetus through the placenta. Maternal antibodies protect the baby for a few months after birth. Such as against diphtherial measles etc.

3. Local immunity

• The concept of local immunity was given by Besredka. (1919-24) Its importance can be for the treatment of localized infection.
•  Which occurs at the entry site of the pathogen.
• Systemic immunity can be generated against the poliomyelitis virus through a killed virus vaccine. 
• It acts against the virus that is in the blood stream. But it is from the moment the virus enters. (the gut, mucosa) does not affect the growth of the virus there. For this, live / oral vaccine is given. Which creates local (intestinal) active immunity
• Influenza immunization with killed vaccine creates systemic antibody response,
•  But it is not useful for local infection of the respiratory tract. For this, live virus vaccine or immunoglobulin is given locally through the nose.

4. Herd Immunity

• It indicates the overall immunity level of a community, it plays an important role in epidemic control. 
• When most of the people in a community are immunized against a pathogen, then the immunity in the entire community against that pathogen is considered satisfactory. When the level of herd immunity is low, there are chances of epidemic.
• Communicable disease eradication is based on a high level of herd immunity and not on a high level  immunity.
• Ex.polio

💪 Mechanism of innate immunity (Mechanism of innate immunity)

• Skin- barrier, high salt concentration in sweat, sebaceous  secretion, and long chain fatty acid  Acts as bacterial cidal (kills bacteria).
• Respiratory tract :-Mucus, cough reflex act as defense mechanism   
• GI-tract :- saliva (saliva), and Acidic PH gastric juice
• Conjuctiva :- Lysozyme present in tears bacteriocidal ,flush wash micro-organism 

Inflammation

• Mast cell –Release histamine which causes vasodilation and thus increases capillary permeability.
• Infected tissue  Inflammation process (Redness, swelling, heat, pain) is necessary for the immune cell to reach it.
• Fever also arises due to the process against this microorganism.

Mechanism of active Immunity(Mechanism of active immunity)

• Humoral immunity :- Which depends on the synthesis of antibodies by plasma cells. In which specific antibodies are produced against specific antibodies and modify their activity.
• Cell –mediated immunity :- It is produced by the sensitivity of T –lymphocytes. Which is very useful for resistance to chronic bacterial infection.

Vaccine

• A vaccine is a preparation of a disease agent or its toxin. When it is introduced into the body, it helps in the production of specific antibodies, or stimulates them. Thus, the vaccine induces active immunity.

Vaccines are prepared in different ways

• (i) Live attenuated organism :- Ex. Polio, Measles, B.C.G vaccine
• (ii) Killed organism:- ex.Cholera vibrio
• (iii) Toxoid :- Ex.Diphtheria, Tetanus
• (iv) Mixed/Combined :- Combination all types of vaccine.

IMMUNIZING AGENTS (Immunization) :-

• Immunization (Immunization) :-

       In which a vaccine is inoculated to bring about individual artificial immunity

•  Immunizing agent (Immunization) :- Immunizing agent It has been divided into two parts. It is divided into two parts.

(1) Vaccine (antigen material)–

(2) Immunoglobulin’s (antibody material)–(gamma globulins)

Vaccination

For the prevention of disease, an organism is introduced from an animal to a human, The principle of vaccination was discovered accidentally in 1776. English physician Jenner observed that milking animals that had been infected with cow pox were protected against the terrible disease small pox. Jenner applied these principles to humans. When material taken from a cow pox eruption was transferred to humans, the humans were able to avoid small pox infection even during the small pox epidemic.

➡ Vaccine and vaccinations

• A vaccine is a preparation of antigen that, when given, produces specific antibodies in the body. formation stimulates.
•  Vaccines are made from live organisms (attenuated), killed organisms, toxoids, or a combination of both. If more than one immunizing agent is present in a vaccine, it is called a mixed or combined vaccine.

Immunization schedule (Immunization schedule)

Immunoglobulins (Gamma gobulins-ગામા ગ્લોબ્યૂલિન્સ) )

• The term Immunoglobulin was first used in 1959 for serum protein. Immunoglobulins produced by the body’s reticuloendothelia’ system are very important for the study of immunity. The human Immunoglobulin system (human serum) is of five classes. IgG, IgA, Ig M, Ig D, Ig E They differ in their  and antigenicity a physical-chemical properties  is.

Ig G:-

It is a very important immunoglobulin containing 80% of the serum antibody of a normal human being. This only Immunoglobulin passes through the placenta and reaches the fetus and provides immunity to the fetus. 

Ig A:-

10% of Antibodies are Immunoglobulin. It  Found in body fluids such as milk, saliva, tears, mucous secretions. Prevents minute leakage of organisms into the circulation from mucous surfaces, its synthesis begins 2 weeks after birth.

Ig M:- 

Human serum contains 5 to 10% antibodies. Its large antibodies are called macroglobulins. They remain intravascular and cannot cross the placenta, and their life is short. It has bacteria killing capacity.

Ig D:-

Less than 1% of total immunoglobulin. Does not have antibody activities.

Ig E:-

It is the lowest amount of immunoglobulin in the body  found in serum at trace levels. Responsible for immediate allergy and anaphylaxis.

            

HYPERSENSITIVITY

• Immunity is seen as a protective process. But it is a small part of the process that occurs for antigen response.
• Many times the immune response can be injurious to the host. Which is also responsible for tissue damage, diseases or death. 
• The harmful effects caused by contact with a specific antigen are called hypersensitivity. 
• Hypersensitivity is divided into two parts based on the time of clinical response development in the host.
• (1) Immediate hypersensitivity (B cell or antibody mediated)
• (2) Delayed hypersensitivity (T cell mediated)

Type-1 Hypersensitivity (Anaphylactic or regain dependents)

• Antibodies are fixed on the surface of   tissue cells (mast cells) and basophiles of the sensitized person.
•  with antigen cell  with fixed antibodies  combined pharmacological active substances that are responsible for causing the clinical reaction.

Type-2 Hypersensitivity (Cytotoxic or cell stimulating)

• This type of reaction begins with the reaction of antibodies against a cell or tissue or the binding of an antigen to a cell 
• In the presence of mononuclear cells, it causes cell damage. Type -II reaction is a reaction between hypersensitivity and autoimmunity.
• The binding of antibodies in many cases works to stimulate the cell rather than causing cell damage. 
• Long acting thyroid stimulator (LATS) is an example of this. Antibodies stimulate thyroid cells and increase the secretion of thyroid hormones.

Type-3 Hypersensitivity (Immune complex or toxic complex disease)

•  In this, damage is caused by antibody – antigen complexes.
•  Its precipitation around small vessels damages the vessels or infiltration into the membrane reduces the efficiency of the membrane.
•  Inflammation occurs due to damage to the walls or basement membranes of small blood vessels

Type-4 Hypersensitivity (Delayed or cell mediated hypersensitivity) )

• Necessary for cell mediated immunity  The reaction is 
• The antigen activates the sensitized T4(TDH) Lymphocytes.
• Which causes the secretion of lymphokines.
•  In this reaction, local infiltration of mononuclear cells is seen.

AUTOIMMUNITY (Autoimmunity)

Autoimmunity

Autoimmunity is a condition where the immune system, which is designed to protect the body against foreign invaders like bacteria and viruses, mistakenly attacks the body’s own tissues and organs. This leads to autoimmune diseases

Key Features:

1. Self-reactivity of the immune system.
2. Chronic inflammation and tissue damage.
3. Can target specific organs or the entire body.

Mechanism of Autoimmunity:

1. Loss of Self-Tolerance (Loss of tolerance to our body’s antigens):
   • Normally, the immune system differentiates between self and non-self antigens.
   • Autoimmunity occurs when this self-tolerance breaks down.
2. Role of Genetics (Role of Genetics):
   • Mutations in genes regulating immune responses can predispose individuals to autoimmunity.
3. Environmental Triggers:
   • Infections, toxins, or stress can activate autoimmunity in genetically susceptible individuals.
4. Molecular Mimicry (Molecular Mimicry):
   • Pathogens may have antigens similar to the body’s own antigens, leading to cross-reactivity.
   • Example: Rheumatic fever after a streptococcal infection.
5. Failure of Regulatory T Cells:
   • Regulatory T cells suppress immune responses against self-antigens.
   • Dysfunction of these cells can lead to autoimmunity.

Types of Autoimmune Diseases:

1. Organ-Specific Autoimmune Diseases:

These diseases affect specific organs.

• Type 1 Diabetes Mellitus (Diabetes):
  Immune cells destroy insulin-producing beta cells in the pancreas.
• Graves’ Disease:
  Overactivity of the thyroid gland due to autoantibodies.
• Multiple Sclerosis (Multiple Sclerosis):
  Immune attack on myelin sheaths in the nervous system.

2. Systemic Autoimmune Diseases:

These diseases affect multiple organs or systems.

• Systemic Lupus Erythematosus (SLE) (Lupus):
  Affects skin, joints, kidneys, and other organs.
• Rheumatoid Arthritis:
  Inflammatory condition targeting joint tissues.
• Sjögren’s Syndrome (Sjögren Syndrome):
  Attacks moisture-producing glands, leading to dry eyes and mouth.

Causes of Autoimmune Diseases:

1. Genetic Predisposition:
   Family history of autoimmune diseases increases risk.
2. Hormonal Factors:
   Women are more prone, indicating hormonal influences.
3. Environmental Factors:
   • Infections, stress, and exposure to toxins.

Examples of Autoimmune Diseases:

1. Hashimoto’s Thyroiditis.
2. Psoriasis.
3. Celiac Disease.
4. Ankylosing Spondylitis.
5. Pernicious Anemia.

• Serological Tests: Principles and Uses
• Principles and Uses of Serological Tests

Principles of Serological Tests:

Serological tests detect antibodies or antigens in a patient’s blood. These tests are based on the specific antigen-antibody interaction, which can be observed or measured through various techniques.

1. Agglutination:
   • Principle: Antibodies cause clumping of particulate antigens.
   • Example: Widal test for typhoid.
2. Precipitation:
   • Principle: Soluble antigen reacts with its specific antibody to form aninsoluble complex.
   • Example: VDRL test for syphilis.
3. Enzyme-Linked Immunosorbent Assay (ELISA) (Eliza):
   • Principle: Uses enzyme-labeled antibodies to detect antigens or antibodies.
   • Example: HIV detection.
4. Immunofluorescence:
   • Principle: Uses fluorescent-labeled antibodies to visualize antigen-antibody complexes.
   • Example: Detection of viruses like herpes simplex.
5. Complement Fixation:
   • Principle: Measures the activity of complement proteins that enhance antigen-antibody reactions.
   • Example: Detection of certain viral infections.
6. Radioimmunoassay (RIA):
   • Principle: Uses radioactive isotopes to measure antigen-antibody interactions.
   • Example: Hormone level testing.
7. Western Blotting:
   • Principle: Separates proteins to detect specific antibodies or antigens.
   • Example: Confirmation of HIV infection.

Uses of Serological Tests:

1. Diagnosis of Infectious Diseases:
   • Identifying pathogens like bacteria, viruses, and fungi.
   • Example: Tuberculosis (TB), hepatitis, and COVID-19.
2. Detection of Autoimmune Disorders:
   • Identifying autoantibodies in conditions like lupus or rheumatoid arthritis.
3. Blood Typing:
   • Determining blood groups before transfusions.
4. Vaccine Efficacy Monitoring:
   • Measuring antibody levels post-vaccination.
5. Pregnancy Testing:
   • Detection of hCG hormone using immunological methods.
6. Cancer Biomarkers:
   • Identifying tumor antigens for early detection.
7. Epidemiological Studies (Public Health Studies):
   • Tracking disease outbreaks by detecting exposure through antibodies.
8. Allergy Testing:
   • Identifying specific allergens triggering immune responses.

These principles and uses make serological tests a cornerstone in modern diagnostic medicine.