Immunology

Immunology Definition

“The study of the immune system, the cell-mediated and humoral aspects of immunity and immune responses.”

Immunology is a branch of biology involved with the study of the immune system, components of the immune system, its biological processes, the physiological functioning of the immune system, types, its disorders and a lot more.

The immune system acts as a body’s defence system by protecting our body cells, tissues and organs from invading infections through various lines of defence. Overall, the immune system functions by recognizing and destroying foreign antigens including harmful microorganisms and other disease-causing microbes.

Under certain conditions, when our immune system is weak or stops functioning, this results in various infectious diseases, such as fever and flu,  and may also lead to dreadful diseases like cancer AIDS, etc.

Also Read: Immunity

Let us have a detailed look at Immunology to learn about the immune system, its different parts, functions and other significance of Immunology.

Immune System

Immune system consists of different types of cells and organs which protect our body against pathogens. Pathogens are defined as microorganisms that cause infections in the body such as bacteria, fungi, viruses and protozoans. Antigens are molecules that elicit antibody generation. They can be everything that does not belong to our body, from parasites to fungi, bacteria, viruses, and haptens. Haptens are molecules that can elicit an immune response when combined with a carrier molecule. All the cells and molecules of the immune system are distributed in all the tissues of the body as well as lymphoid organs which eliminate microbial infectious diseases, decrease the growth of tumours and starts the repairing process of damaged tissues.

The tissues and organs of the immune system act as security forces where cells act as the security guards while molecules act as the guns & bullets and use the communication system to protect you.

Types of Immune System

We, humans, have two types of Immune system and are classified based on whether they are present at the time of birth or not.

1. Innate Immune System.
2. Adaptive Immune System.

Innate Immune System

Immune System fights against microbes and prevent their entry inside the body.

Innate Immune System is composed of cells and proteins that are always present and are ready to fight against microbes in the infection area. Innate Immune System is present from the time of our birth.

Main elements of the innate immune system are –

• Dendritic cells.
• Phagocytic leukocytes.
• Natural killer (NK) cell.
• Physical epithelial barriers.
• Circulating plasma proteins.

Adaptive Immune System

The adaptive immune system is required to fight against pathogens that cannot be controlled by innate immune defences. It is also referred to as the acquired immune system because it is acquired during the course of life. They are specific to the type of pathogen invading the body.

All the components of the adaptive immune system are generally inactive however when activated these components adjust to the presence of all the infectious agents by proliferating and developing a potent mechanism for eliminating the microbes.

Two Types of adaptive responses are – humoral immunity moderated by antibodies which are developed by B lymphocytes and cell-mediated immunity, moderated by T Lymphocytes.

Immunology and Diseases

Immunological diseases are caused by defects in immune system. The immune system may be hyperactivated to release antibodies and other chemicals. This results in allergy and anaphylaxis. Sometimes the immune system fails to differentiate self cells from no-self cells, resulting in autoimmune diseases. In this situation, the immune system is challenged and evoke responses that damage cells and tissues rather than protecting. All the immunodeficiency diseases increase the risk of tumours and infections and are caused by malnutrition, immune suppresents, gene mutations, and viruses such as HIV.

Also Refer: Antigens and Immunology

Symptoms of Immune Dysfunction

• Bowel disorders.
• Parasite infections.
• Candida overgrowth.
• Allergies and Asthma.
• Frequent colds and flu.
• Autoimmune disorders.
• Painful joints and muscles.
• Herpes (cold sore) outbreak.
• HPV and abnormal PAP smears.
• Rhinitis or a constant runny nose.
• Psoriasis, eczema, hives or rashes.

Immunology Techniques

This is an experimental method used for studying the structure and functions of the immune system. There are different techniques, which includes:

• ELISA.
• ELISPOT.
• Immune cell isolation.
• Immuno-histo-chemistry.
• Generation of Antibodies.
• Immuno-blotting and precipitation.
• Isolation and Purification of Antibodies.

Applications of Immunology

Immunology is widely used in numerous disciplines, including medicine, in the fields of organ transplantation, bacteriology, oncology, virology, parasitology, rheumatic diseases, psychiatric disorders, and dermatology. The Immunology of transplantation mainly deals with the process of transplantation from a donor to the recipient, so that the recipient’s body does not reject the organ.

This was a brief introduction to Immunology, for more information on Immunology, immune system, its techniques, notes for Immunology Class 12, visit us at BYJU’S Biology.

Immunity

In biology, immunity is the state of being insusceptible or resistant to a noxious agent or process, especially a pathogen or infectious disease. Immunity may occur naturally or be produced by prior exposure or immunization.

Types of Immunity

The body relies on the adaptive immune system and immunological memory to provide immunity and prevent recurrent infections with the same illness. This can also be taken advantage of within medicine through things such as vaccinations.

The various ways in which immunity is developed are generally split into ‘active’ (i.e. due to the body’s own immune response and immune cells) and ‘passive’ (i.e. as a result of antibodies) immunity. This article will consider the different types of immunity and finally, their roles within the immune system.

Active Immunity

Active immunity is when the body’s own immune system mounts an adaptive immune response following direct exposure to a disease organism or antigen. It can develop either naturally or artificially.

Active immunity, in contrast to passive immunity, takes time to develop but is long-lasting as it produces memory lymphocytes that recognise the disease and promptly produce the antibodies needed to fight it.

Natural

Generally speaking, natural active immunity happens after infection with the actual disease. Exposure to the pathogen and the subsequent immune response produce memory cells that can recognise and rapidly respond to the pathogenic agent on re-exposure.

Artificial

Vaccination can artificially stimulate active immunity. In brief, this is where the body is exposed to a dead or weakened form of the pathogen, which, though unable to mount an infection, still activates the adaptive immune response and memory cell formation.

The main advantage of vaccination is that it avoids the need for an active infection to confer immunity which can be fatal in some diseases.  However, some pathogens change their antigen structure over time (particularly viruses), enabling them to evade immunological memory. This might necessitate re-vaccination such as the case with the influenza virus vaccine.

Passive Immunity

Passive immunity relies on antibodies rather than memory cells. In brief, It involves the introduction of ready-made antibodies to a non-immune individual.

Passive immunity is short-lived (because there are no memory cells) but beneficial where there is a high risk of infection, and the body is unable to develop its own immune response or synthesize its’ own antibodies. It can also alleviate the symptoms of some diseases and treat certain infections that have no available vaccine (e.g. Ebola virus).

Furthermore, they can be used prophylactically in immunodeficient patients and where there is insufficient time for the body to develop its own immune response. for example, antivenom serum for poisoning.

Natural 

Passive immunity can be passed down in the form of IgG from mother to foetus. IgG is the only antibody subtype that can cross the placenta and subsequently provides protection for 4 to 6 months after birth.

After that, maternal antibodies are gradually degraded as the infant’s immune system continues to develop until it reaches maturity at around 5 years of age.

IgA antibodies present in breast milk can also transfer passive immunity. IgA coats the gastrointestinal tract of the infant, protecting against bacterial infections until the newborn’s immune system is mature enough to produce its own antibodies. This immunity is short-lived, and vaccination is required shortly after birth to prevent diseases such as tuberculosis and hepatitis B.

Artificial

IgG antibody transfer can provide artificial passive immunity.

These can be through several ways:

• Human or animal blood products – serum or plasma
• Pooled human immunoglobulin – intravenous, subcutaneous or intramuscular immunoglobulin from immunised donors or those recovering from the disease.
• Monoclonal antibodies

The protection conferred is immediate but temporary. Furthermore, as the body does not develop memory cells, the patient is at risk of disease relapse or re-infection unless they develop active immunity.

 

 

Active vs. Passive Immunity – Summary

 

Frequently Asked Questions on Immunology

Q1

What is ELISA?

Enzyme-Linked ImmunoSorbent Assay is known as ELISA. It uses antibodies to detect the presence of certain proteins in the sample. ELISA is used as a diagnostic tool.

Q2

What is hay fever?

Hay fever is the allergic response to certain allergens from the environment such as pollens, dust mites and fur.

Q3

What is graft rejection?

Graft rejection is the immune response happening in the recipient’s body, that attack and destroys the donated organ.

Q4

What is histocompatibility?

Histocompatibility is the property of having similar alleles in the Major Histocompatibility Complex [MHC]. It is required for organ transplantation.

Q5

Is thymus present in adults?

The thymus is active till puberty and after that, it slowly degenerates and is replaced by fat tissues.