Innate And Adaptive Immune Systems

Innate and adaptive immune systems are two main types of immune systems of a living organism to defend against pathogen/ substance which act as foreign substances to the body of that particular organism. The main and first difference between these two systems is their way of dealing with pathogens i.e. innate immune system of non-specific type and adaptive immune system of highly advanced and specific type of immune system.

Innate Immune System

 It is the most primitive type of immune system found in primitive multicellular organisms, insects, fungi and plants to the most evolved vertebrates. Innate immune system comprises

• Anatomical barriers: skin, sweat, dead cell layers
• Epithelial surface: causes barrier for entry of pathogens.
• Respiratory cilia: Pushes particles outwards from respiratory tract.
• Nasopharynx: Mucous secretion
• Eyes: Tears
• Gastrointestinal tract: Gastric acids, peristalsis, digestive enzymes.

In vertebrates, innate immune system is mediated through ‘Cytokines’ which is a specialized chemical mediator that helps to activate the cells of inflammation. These are histamine, serotonin, leukontrienes, bradykinin, etc.  This inflammatory response have the following symptoms

• Redness
• Pain
• Heat
• Swelling
• Dysfunction (in severe cases)

Once the immune system is activated by cytokines, a series of chemical cascade takes place which identifies bacteria and activates cells to clear the dead cells/ antibody complexes.

Cells involved in innate immune system are

• Phagocytes
• Mast cells
• Macrophages, neutrophils
• Dendritic cells
• Natural killer cells in liver.

Adaptive immune system

 It is a more specific type of immunity. Its most special feature is its ‘Memory Cells’ i.e. once the antigen is recognized by the adaptive immune system, its memory cells are formed and maintained throughout the life of the organism.

Some main functions of Adaptive Immune System

• Recognition of self and non self antigens.
• Response generation to eliminate the pathogen.
• Memory building to prevent future quick action.

The mediator of adaptive immune system is Lymphocyte cells.

These are:

• B. lymphocytes
• T .lymphocytes

B lymphocytes are the major cells involved in antibodies formation. They are present in blood plasma and lymph nodes and hence, this is also known as humeral immune system. It produces five types of antibodies IgA, IgG, IgD, IgE, IgM each having its own specialty and actions against specific type of antigen.

T lymphocytes have the following sub categories

• Cytotoxic cells: CD8+ cells which kill cells infected with pathogens.
• Helper T cells: these cells help other adaptive immunity cells to manage the immune response.
• Gamma delta cells: these cells have combined properties of cytotoxic, helper cells and natural cells.

This is in brief about innate and adaptive immune systems which can be given the credit for successful and healthy life of any living creature. They also can be named as Health Department of a living organism.