IMMUNOLOGY AND SEROLOGY

 IMMUNOLOGY AND SEROLOGY

IMMUNOLOGY         

It is the study of host’s reactions when the foreign substances are introduced in to the body or it is the branches of science that deals with the body’s resistance to infectious agent.

Immunology is a study of how the molecules, the cells, the organs and the system in our body recognize and dispose these foreign materials/ substances, so that means it’s the study of recognition and disposal of foreign substances (antigens).

Immunology deals with body components, how it responds, how it interacts and the undesirable of these immune consequences.

SEROLOGY

The branch of science dealing with the measurement and characterization of antibodies, antigens and the other immunological substances in body fluids or serum.

It deals with our serum to know their immunological reactions and properties or it is the interactions of antigens and antibodies.

It is derived from the Latin word:

                                                          Sero = serum

GENERAL ROLE OF IMMUNE SYSTEM

Ø  Defending the body against infection.

Ø  Recognizing and responding to foreign antigens.

Ø  Defending the body against the development of tumors.

DISTINCTIVE CHARACTERISTICS OF IMMUNE SYSTEM

•         Specificity
•         Memory
•         Mobility
•          Replicability 
•          Cooperation between different cells or cellular products.

Ø  Specificity and memory includes the production of antibodies whenever we exposure to foreign antigen. Specificity and memory are the characteristics of lymphocytes.

Various specific and non specific elements of immune system can demonstrate mobility that is the resaon why sometimes if we have local sensitization just like an insect bite it could result systemic sensitization because agains the cells of imune system are having this mobility. So, it includes T and B lymphocytes, antibodies, or the immunoglobulin.

 

IMMUNITY

It is the ability of the body’s to resist infectious agent or other words the state of the body which learns from the experience of past infections, how to deal more efficiently with subsequent infections.

It is derived from the Latin word:

                                                          Immunis = “exempt or freedom”

Immunity is the condition of being resistance to infection. So, it reflects how the body‘s  immune defense would interact to protect us from these invading pathogens that cause this infectious diseases.

TYPES OF IMMUNITY

Ø  1^st line defense includes the external components which includes physical and biochemical barriers of the immune system.

Ø  2^nd line defense includes Cellular and Fluids components of the immune system.

Ø  3^rd line of defense which is under adaptive immunity which is further divided into Cellular and Humoral Immunity.

Ø  Cellular immunity is mediated by T lymphocytes whereas the humoral immunity is mediated by B lymphocytes and both of them are further sub divided into either active and passive immunity.

NATURAL IMMUNITY

It is also known as innate/ non- specific immunity. It is non- specific because this type of immunity uses the same defense mechanisms regardless of the character of the foreign antigen and protection by natural means without the production of antibody. It is already present at birth and lacks memory. Natural immunity has a uniform response so that the primary response is equal to the secondary response so that means the mechanism doesn’t alter on repeated exposure to any antigen.

FIRST LINE:

Physical barrier

Ø  Skin

Ø  Mucous membrane

Ø  Cough reflex

Ø  Cilia

Biochemical barrier

Ø  Lysozyme (tears and saliva)

Ø  Lactic acid (sweat)

Ø  Sebum (oil produced by skin)

Ø  Earwax (cerumen)

SECOND LINE:

Cellular:

Ø  Phagocytic cells (monocytes, macrophages, polymorphonuclear cells)

Ø  Eosinophils

Ø  Basophils and mast cells

Ø  Natural killer cells

Humoral:

Ø  Complement (major component)

Ø  Cytokines (interferon, interleukin)

Ø  Beta lysin

Cellular Components:

The main difference between the monocytes and the macrophages is that the monocytes contain peroxidase whereas macrophages does not contain peroxidase.

In terms of phagocytosis macrophages may not be as efficient as the neutrophils because the motility of the macrophages is low as neutrophils that’s why if there is infection the 1^st type of cells that would go to the site of infection is neutrophils.

Eosinophils commonly increased during parasitic and allergic reaction. Basophils and mast cells for allergic reaction.

Humoral Components:

Major component is complements (complement of alternative pathway). Complement of alternative pathway because the alternative pathway of complement does not involve antibody production but classical pathway of complement is that involve the production of antibody. That’s why the alternative pathway of complement is specified.

Interferon are like natural antibiotic (protein) are produced by many cells in response to viral infection. They are called interferon because they block or interfere with the replication of virus.

ACQUIRED IMMUNITY

This is also known as Adaptive immunity/ Specific immunity. Acquired immunity is not present at birth so we are born with ability to produce acquired immunity but the response is not immediately available so this is a diverse type of response because the secondary response is greater than primary response. It has memory so it can recall previous antigen.

THIRD LINE DEFENSE:

Cellular Components

Ø  Specialized lymphocytes (T and B lymphocytes, plasma cells)

Ø  Antigen present cells (monocytes, macrophages)

Humoral Components

Ø  Antibodies

Ø  Cytokines

Ø  Complement (classical pathway)

Humoral Components:

Humoral immunity is a type of immunity that results from the formation of antibody. So, if a microorganism already overwhelms the body’s natural immunity or natural resistance there is this 3^rd line of defense that will come. So, this type of acquired immunity is a mechanism that would allow us to recognize, to remember and to respond specific antigen. Major components of acquired immunity in humoral components is antibodies.

Main function of humoral immunity is:

Ø  Recognize

Ø  Remember

Ø  Respond

Acquired immunity can result in the elimination of microorganisms and recovery from disease and the host often acquires a specific immunologic again memory, so there is memory in the acquired immunity. This condition of memory or sometimes called recall that allows the host to respond more effectively if reinfection with the same microorganism or same antigen.

Cellular Components:

 Major components of acquired in cellular components is lymphocytes. T and B lymphocytes or activated B lymphocytes which are differentiated into plasma cells and plasma cells are capable to produce antibodies.

TYPES OF ACQUIRED IMUNITY

A) Active Acquired Immunity

B) Passive Acquired Immunity

ACTIVE ACQUIRED IMMUNITY

If there is introduction of “antigen” then the host’s body produces antibody, the immunity develops slowly and persists for a long time. It is of two types:

1) Natural Active Acquired Immunity:

When antibody is produced due to natural infection by infectious agent.

2) Artificial Active Acquired Immunity:

When antibody is produced by the host’s body in response to inoculation of an antigen.

PASSIVE ACQUIRED IMMUNITY

The antibody is produced elsewhere and subsequently introduction into host’s body. The immunity is rapidly established but persists for short duration. It is of two types:

1) Natural Passive Acquired Immunity:

Ø  Maternal antibody from mother to foetus.

Ø  Colostrum through milk from mother to infants.

2) Artificial Passive Acquired Immunity:

Ø  Transfer of lymphocytes or immune cells

Ø  By injection of anti-rabies vaccine