Innate Immunity

Natural killer cells are a type of Large granular lymphocytes (LGL). They are cytotoxic against malignant and viral cells.

Their activity does not depend on sensitization by prior antigenic contact and therefore are part of natural or innate immunity.

Ref: Textbook of Microbiology, Ananthanarayan and Paniker, 7th Edition, Chapter 15, Page 126; Greenwood Microbiology 14^th Edition, Page 147; Harrisons Internal Medicine 16 ^th  Edition, Page 1025, 1909, 1917.

Ans. is ‘a’ i.e., NK Cells

. NK cells are part of innate immunity

.  NK cells are considered to be important in immune surveillance and natural defence against virus infected and malignant mutant cells.

Ans. is ‘d^‘ i.e., T cells

Ans.C.  Not affected by genetic makeup

• It is the resistance to infections which an individual possesses by virtue of his genetic and constitutional makeup.
• Innate immunity, also called native immunity, exists by virtue of an organisms constitution, that is its genetic make-up, without external stimulation or a previous infection.
•  It is divided into two types: (a) Non-Specific innate immunity, a degree of resistance to all infections in general. (b) Specific innate immunity, a resistance to a particular kind of microorganism only. As a result, some races, particular individuals or breeds in agriculture do not suffer from certain infectious diseases.

Ans. is ‘b’ i.e., Complement proteins

Ans. is ‘b’ i.e., Antibody

Ans. is ‘a’ i.e., Recognised foreign antigen in blood

The physiological function of the immune system is to protect individuals from infectious pathogens. The mechasnisms that are responsible for this protection fall into two broad categories ‑

Innate (Native Immunity)

o It is the resistance to infections which an individual possesses by virtue of his genetic and constitutional make up. o It is the first line of defence against infectious agents.

o It is present since birth and is found both in invertebrates and vertebrates.

o It is not affected by prior contact with microorganisms or immunization ie antigen exposure is not required for its development.

o There is no immunological memory.

o It is nonspecific, it is active against a wide range of infectious agents.

o Sometimes the innate immunity itself is able to control the infection on its own but sometimes the defence of the innate immunity is breached, then the adaptive immunity is called into action.

Important components of the innate Immune system.

1. Cells Macrophages, Dendritic cells, NK cells, NK-T cells, Neutrophils, Eosinophils, mast cells, basophils, epithelial cells.
2. Complement components Classical and alternative pathway.
3. Antimicrobial peptides Defensins, cathelin, probiatics.

4.Pattern recognition receptors

5.Cytokines.

Adaptive (Acquired) immunity

o Adaptive immunity is found only in vertebrates

o It is based on the generation of antigen receptors on T and B lymphocytes by genn line gene rearrangements. o It is specific.

o It is developed as a result of an antigenic stimulus (Immunological priming).

o It provides immunological memory; subsequent antigen exposure leads to more rapid and vigorous immune responses.

o The adaptive immune system consist of dual limbs of cellular and humoral immunity. Component of the adaptive immune system.

1. T cells                          3. Antibody
2. B cells                         4. Plasma cells

Ans. C: NK cells

NK cells play a major role in the rejection of tumors and cells infected by viruses.

They kill cells by releasing small cytoplasmic granules of proteins called perforin and granzyme that cause the target cell to die by apoptosis.

Ans. is ‘c’ i.e., Macrophages 

Macrophages and neutrophils are phagocytic cells that engulf a microbial pathogen after it has been identified by the innate immune system