immunity

 Definition - 

Immunology -

 Immunology is the science which deals with the body’s response to antigenic challenge.

Immunological mechanisms are involved in the protection of the body against infectious agent.

Immunity - 

The resistance (प्रतिरोध) offered by the host to the harmful effect of pathogenic microbial infection is called immunity. Immunity against infectious diseases.

ANTIGEN - Enterovesicular is a substance which, when introduced parenterally into the body, stimulates the production of an antibody with which it reacts specifically in an observable manner.

allergens, blood group antigens, HLA( human leukocyte antigen ), substances on the surface of foreign cells, toxins

(एंटीजन एक ऐसा पदार्थ है, जो जब शरीर में पैरेन्टेरली पेश किया जाता है, तो एक एंटीबॉडी के उत्पादन को उत्तेजित करता है जिसके साथ यह विशेष रूप से एक अवलोकन योग्य तरीके से प्रतिक्रिया करता है।)

ANTIBODIESC (Immunoglobulins ) - Antibody is defined as humoral substance (γ-globulin) produced in response to an antigenic stimulus. It serves as protective agent against organisms. Antibodies are found in serum, lymph and other body fluids.

Antibodies are:

1. Protein in nature.

2. Formed in response to antigenic stimulation.

3. React with corresponding antigen in a specific and observable manner.

(Plasma is the largest part of your blood. ... When separated from the rest of the blood, plasma is a light yellow liquid. Plasma carries water, salts and enzymes. The main role of plasma is to take nutrients, hormones, and proteins to the parts of the body that need it. Cells also put their waste products into the plasma.)

(Serum is the fluid and solute component of blood which does not play a role in clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. ... To obtain serum, a blood sample is allowed to clot (coagulation).

Immunoglobulins-

Immunoglobulins are synthesized by plasma cells and also by lymphocytes. Immunoglobulins make 20 to 25 percent of the total serum proteins. The term immunoglobulins is the structural and chemical concept while antibody is biological and functional concept. All antibodies are immunoglobulins but all immunoglobulins may not be antibodies. Based on their size, carbohydrate contents and amino acid analysis, 

there are five group of immunoglobulin -

IgG - major Ig,It passes through placenta and  provide natural passive immunity to newborn.

 IgA - It is found in high concentration in colostrum, tear, bile, saliva,intestinal and nasal secretions.It promotes phagocytosis and intracellular killing of organisms.

 lgM- It is more efficient in agglutination, cytolytic and cytotoxic reaction. IgM deficiency is often associated with septicemia.It was first detected by Rose and Fahey in 1965.

 IgD -IgD may function as mutually interacting antigen receptor for the control of lymphocyte activation and suppression.

 IgE. -It is reaginic antibody responsible for immediate hypersensitive reactions.

types of immunity -

INNATE IMMUNITY

This is basic immunity which may be genetically passed on from one generation to other generation. It does not depend on prior contacts with microorganisms. It may be nonspecific when it indicates a degree of resistance to all infection, e.g. plant pathogens, rinderpest, distemper. It is specific when it shows resistance to particular pathogens. 

(यह बुनियादी प्रतिरक्षा है जो आनुवंशिक रूप से एक पीढ़ी से दूसरी पीढ़ी को हस्तांतरित की जा सकती है। यह सूक्ष्मजीवों के साथ पूर्व संपर्कों पर निर्भर नहीं करता है। यह निरर्थक हो सकता है जब यह सभी संक्रमणों के प्रतिरोध की डिग्री को इंगित करता है, उदा। पौधे के रोगजनक, रिंडरपेस्ट, डिस्टेंपर। यह विशिष्ट है जब यह विशेष रोगजनकों के लिए प्रतिरोध दिखाता है।)

Innate immunity can be divided into following types -

nonspecific, immunity - 

 nonspecific, immunity is the defense system with which you were born. It protects you against all antigens. Innate immunity involves barriers that keep harmful materials from entering your body.

(गैर-विशिष्ट, प्रतिरक्षा वह रक्षा प्रणाली है जिसके साथ आप पैदा हुए थे। यह आपको सभी एंटीजन से बचाता है। जन्मजात प्रतिरक्षा में बाधाएं शामिल होती हैं जो हानिकारक पदार्थों को आपके शरीर में प्रवेश करने से रोकती हैं)

Examples of innate immunity include:

• Cough reflex.
• Enzymes in tears and skin oils.
• Mucus, which traps bacteria and small particles.
• Skin.
• Stomach acid.

-The adaptive immune system, also known as the acquired immune system, -

ACQUIRED IMMUNITY -

The immunity acquired during the lifetime of an individual is known as acquired immunity. Acquired immunity differs from innate immunity in the following respects:

1. It is not inherent in the body but is acquired

during life.

2. It is specific for a single type of microorganism.

Acquired immunity may be:

1. Active.

2. Passive.

Active immunity:-

 It is the resistance developed by an immunity as a result of antigenic stimulus.

Active immunity may be:-

Natural active immunity:- This is acquired after one infection or recovery from disease or subclinical infection after repeated exposure to small doses of the infecting organism.

 who becomes infected with chickenpox. After the initial infection, the body builds immunity against the disease. This natural active immunity is why people who catch chicken pox are immune for many decades against the disease

Artificial active immunity: It may be acquired artificially by inoculation of bacteria, viruses or their products as under: vaccination.

Passive Immunity: - 

Here subject is immunized by prepared antibodies and body cells do not ntake any active part in the production of immunity. It is of the following types:

Natural passive immunity: -

During intrauterine life transmission of antibodies from the mother to fetus can occur through placenta. It may be by way of colostrum of mother and milk

during first few months of life. Breast-fed infants resist establishment of enteroviruses in

alimentary tract. These antibodies last for few weeks and protect infants from diphtheria,

tetanus, measles, mumps, smallpox, etc. 

Artificial passive immunity:-

 Immunization in this case is passive and produced by injection of serum of animals that have been immunized actively. Antibodies remain in effective

quantity for 10 days only. eg - readymade immunity.

Differences between active and passive immunity

                     Active immunity                                                                      Passive immunity

1. Produced actively by host’s immune system            -    Received passively by the host. No participation by

                                                                                             host’s immune system

2. Induced by infection or by contacts with                    -  Conferred by introduction of vaccines, e.g. readymade

immunogen antibody

3. Afford durable and effective protein                              - Temporary and less effective protection

4. Immunity effective after lag phase                             -   Immunity effective immediately

5. Immunological memory present, i.e                           -. No immunological memory

subsequent challenge more effective

6. Negative phase may occur                                           -  No negative phase

7. Not applicable to immunodeficient hosts                      - Application to immunodeficient hosts

8. Used as prophylaxis to increase resistance                    -Used for treatment of acute infection

of body

9. Both cell mediated and humoral immunity                    -Exclusively humoral immunity is involved

take part

10. No inheritance of immunity                                          - May be acquired from mother

Hypersensitivity -

Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. They are usually referred to as an over-reaction of the immune system and these reactions may be damaging and uncomfortable.

(It is defined as altered state induced by an antigen in which pathological reaction can be subsequently elicited by that antigen or by structurally similar substance )

The four types of hypersensitivity are:( immediate reaction and dealyed reaction.)

I. Immediate hypersensitivity: In immediate hypersensitivity the symptoms are manifest within minutes or hours after a sensitized recipient encounters antigen.

II. Delayed hypersensitivity: Delayed type hypersensitivity (DTH) is so named in recognition of the delay of symptoms until days after exposure.

• .

Differences between immediate hypersensitivity reaction and

delayed hypersensitivity reaction

       Immediate reaction                                                        Delayed reaction

Immediate reaction	Delayed reaction
1. Appears and recedes rapidly	Appears slowly and lasts longer
2. Induced by antigen or hapten by any route	Induced by infection, injection of antigen with Freund’s adjuvant or by skin contact
3. Circulating antibodies present and responsible for reaction (antibody mediated reaction)	Cell mediated reaction and not antibody mediated
4. Passive transfer possible with serum	Transfer possible by lymphocytes or transfer factor
5. Desensitization easy but short lived	It is difficult but long lasting
6. Lesions are acute exudation and fat necrosis	Mononuclear cell collection around blood vessels
7. Wheal and flare with maximum diameter Erythema and induration with maximum diameter in 6 hours	Erythema and induration with maximum diameter  in 24 to 48 hours

                                                                         

TEST OF THE HYPERSENSITIVITY -

VACCINE -

“vaccine” means any substance designed to be administered to a human being for the prevention of 1 or more diseases.

TYPES OF VACCINE -  

Live attenuated Vaccines

Live attenuated vaccines contain whole bacteria or viruses which have been “weakened”(attenuated) so that they create a protective immune response but do not cause disease in healthy people. Live vaccines tend to create a strong and lasting immune response and include some of our best vaccines.

Inactivated Vaccines / killed vaccine - 

Inactivated vaccines contain whole bacteria or viruses which have been killed or have been altered, so that they cannot replicate. Because inactivated vaccines do not contain any live bacteria or viruses, they cannot cause the diseases against which they protect, even in people with severely weakened immune systems. However, inactivated vaccines do not always create such a strong or long-lasting immune response as live attenuated vaccines. 

(निष्क्रिय टीकों में पूरे बैक्टीरिया या वायरस होते हैं जिन्हें मार दिया गया है या बदल दिया गया है, ताकि वे दोहरा न सकें। क्योंकि निष्क्रिय टीकों में कोई जीवित बैक्टीरिया या वायरस नहीं होते हैं, वे उन बीमारियों का कारण नहीं बन सकते जिनसे वे रक्षा करते हैं, यहां तक ​​कि गंभीर रूप से कमजोर प्रतिरक्षा प्रणाली वाले लोगों में भी। हालांकि, निष्क्रिय टीके हमेशा इतनी मजबूत या लंबे समय तक चलने वाली प्रतिरक्षा प्रतिक्रिया नहीं बनाते हैं जैसे कि जीवित क्षीण टीके।)

Toxoid vaccines - 

Toxoid vaccines use a toxin (harmful product) made by the germ that causes a disease. They create immunity to the parts of the germ that cause a disease instead of the germ itself. That means the immune response is targeted to the toxin instead of the whole germ.