Adaptive Immune System or Acquired Immune System or Specific Immune System

As we are moving further in the better understanding of Immune System, today’s blog is about,

·        What is Adaptive Immunity or Acquired Immune System ?

·        How Immune System detects pathogens inside our body ?

·        What Immunity do to meet its goal of being defensive ?

·        How a specific biological or Immunological memory is created ?

·        What are the differences between Innate Immunity and Acquired Immunity ?

Okay Guys!!  No Worries.

In this post we are going to cover each and every biotechnological aspects of Immune System, which in turn will cover all these questions.

We, as humans, are blessed with two types of Immune System. They are,

Ø Innate or Natural Immunity

Ø Adaptive or Acquired Immunity

Innate or Natural Immunity was very well explained in the last post 'Innate/ Natural Immunity' to clear all your doubts.

Here, we will study about the Adaptive or Acquired Immune response for better understanding of Immunity process or Immune System.

Adaptive Immunity or Acquired Immunity  :

Only vertebrates have adaptive immunity.

It ‘remembers’ the previous infection and so has tremendous survival in pathogen filled environment.

Therefore, it is referred to as Adaptive Immunity or Acquired Immunity.

Adaptive Immunity

The adaptive or acquired immune response comprises of   specialized cells and processes to kill pathogens or prevent their attack.

The adaptive immune system is focused towards specific targets.

This immune system provides stronger attacks each time a particular pathogen is encountered.

The major characteristic attributes of adaptive or acquired immunity are:

·        Self and non self recognition

·        Antigenic Specificity

·        Diverse Immunologic memory

1.     Why ‘adaptive’ ?

It is ‘adaptive’ because our natural defender or body’s immune system prepares itself for future pathogenic encounters.

2.     Being ‘specific’ in action :

A layer of protection i.e. adaptive immune system is activated if the pathogen make its way in our body by evading the innate immune system.

Thus adaptive or acquired immune system adapts its response during an infection, in being specific  and improve in reorganization of the pathogens.

3.     Property of memory

After killing or removal of pathogens, B cells and T cells continues their working mechanism, which creates an ‘Immunological memory’.

These cells make adaptive or acquired immune system to work stronger and faster each time there is a pathogenic encounter.

Agents of Adaptive or Acquired Immunity:

The adaptive or acquired immune response work under two types of mechanism. They are :

Ø Humoral Immune response

Ø Cell mediated Immune response

Ø Humoral Immune response :

The production of immunity by administration of antibodies from an immune person.

Ø Cell mediated Immune response:

Immune response produced only by administration of T cells from an immune   individual.

This immune response plays an important role in lysis of tumor cells and virus infected cells.

1.     Cells involved in Adaptive or Acquired Immunity :

Adaptive or Acquired Immune response categorizes the cells involved into two types:

a)    Lymphocytes

b)    Antigen presenting cells

Above mentioned both the cells i.e. (lymphocytes and antigen presenting cells) are explained in previous post 'Cells Of Immune System' , but here we will study then with a different perspective.

a)    Lymphocytes :

The lymphatic system carries infection fighting cells, which are involved in removal of foreign material i.e. pathogens and cell debris known as lymphocytes.

Lymphocytes

The lymphocytes are categorized into two types:

Ø T cells

Ø B cells

Readers can visit my previous post to get into the concepts of T cells and B cells mentioned below.

1.     ImmuneSystem Basic Concepts: Your Natural Defense and Body Cleanser

2.     Innate/Natural Immunity (OUR BODY’S FIRST LINE OF DEFENCE)

3.     CellsOf Immune System

Ø T Cells :

1.     The working process of T cells starts in our body, as soon as they have a combat with the cells.

2.     These cells can be B cells or dendritic cells, which have digested an antigen and are showing antigen fragments linked to T cell’s MHC (Major Histocompatibility Complex) molecule.

3.     The MHC- antigen complex activates T cell receptor and cytokines are secreted by T cell.

4.     These cytokines help T cell to mature.

5.     Some cytokines increase the growth of more T cells.

6.     Some of the T cells become cytotoxic (T_c) and kill viral infected cells.

7.     Some T cells become helper cells (T_h) and secrete cytokines to attract fresh macrophages, neutrophils, other lymphocytes and other cytokines to monitor and direct them, once they reach the site of infection.

The working mechanism can be better understood by the following graphical representation.

T cell Mechanism 

Ø B cells :

B cells create and secrete antibodies which target pathogens and attach with them. This enhances the destruction of pathogens by other parts of immune system.

B cells work in the following pattern:

1.     Antibody (Ab) or Immunoglobin(Ig) receptors present on B cell surface recognize and attach to antigens (Ag) and process of  destruction or deactivation of foreign invaders is activated.

2.     Inside B cell, a fragment of antigen combines with Human Leukocyte Antigen (HLA) class II.

3.     This human leukocyte class II- antigen fragment complex is displayed on B cell surface.

4.     T helper cells (T_h) receptors recognize HLA class II- antigen fragment complex gets activated and produce cytokines, in turn activating B cells.

5.     B cells activated by cytokines start replication or expand clonally.

6.     Some of the B cells become antibody (Ab) producing plasma cells.

Diagrammatically, the process can be explained as follows:

b)    Antigen presenting cells:

These cells are clarified in the previous post 'Cells Of Immune System'

and now we will extend our knowledge to make the topic more logical and understandable.

1.     A pathogen or extracellular antigen (Ag) is phagocytized by an antigen presenting cells or more likely a dendritic cell and gets into a vesicle.

2.     Lysosomes digest the ingested pathogen to extract their antigen.

3.     The antigen binds with the major histocompatibility complex (MHC) protein which enter the vesicle.

4.     The MHC protein having antigens release from the vesicle and travel to the outer surface of cell membrane.

5.     The dendritic cells present antigens (Ab) , which in turn  activates T cells, which bind with the major histocompatibility complex (MHC) protein.

I hope, I have made myself very much clear to my readers in understanding of the topic  “ Adaptive or Acquired Immunity ”.

Moving on, now we will discuss about the major differences between two types of immunity i.e. Innate Immunity and Adaptive Immunity.

Difference between Innate Immunity and Adaptive Immunity :

S.No.	INNATE IMMUNITY	ADAPTIVE IMMUNITY
1.	Found in all forms of life	Found only in vertebrates
2.	First line of defense	Second line of defense
3.	Non – specific response	Antigen specific response to pathogens
4.	Provides immediate action	Lag time in activation
5.	No immunological memory	Possess immunological memory
6.	Effector molecules are cytokines	Antibodies being the effector molecules.

I hope this will clear all your doubts.

I would suggest you to check all my previous posts as well to get the insight of all these topics and help you in forming your basics on Immune System in Biotechnology.

1.     ImmuneSystem Basic Concepts: Your Natural Defense and Body Cleanser

2.     Innate/Natural Immunity (OUR BODY’S FIRST LINE OF DEFENCE)

3.     CellsOf Immune System

Still have lot more to share, Stay connected.

Thank you & Happy Biotechnology Learning!!!