Question

What is innate immunity? Mention any two types of innate immunity barriers.

Answer 1

Innate immunity, also known as non-specific immunity, is present at the time of birth and passed down genetically from parents to children. Innate immunity consists of following barriers:

(i) Physical barriers: These barriers prevent the entry of foreign organisms into the body. These include skin and mucous membrane.

(ii) Physiological barriers: Body temperature, pH of the body fluids and other body secretions prevent growth of several disease causing microorganisms. Some of these barriers include hydrochloric acid secreted by stomach, bile juice secreted by liver, earwax, tears from eyes as they contain lysozymes, etc.

(iii) Cellular barriers: Certain types of blood cells called leucocytes (WBC) like Polymorpho-Nuclear Leucocytes (PMNLs) or neutrophils and monocytes, natural killer cells (type of lymphocytes) as well as macrophages are the most important phagocytes that destroy the pathogens by phagocytosis.

(iv) Cytokine barriers: Certain kinds of cells when infected with a virus, release interferons which make the cells resistant to viral infections.