Innate Immunity - Practice Questions & MCQ

• Innate immunity is a non-specific type of defence, that is present at the time of birth. 
• This is accomplished by providing different types of barriers to the entry of the foreign agents into our body. 
• Innate immunity consists of four types of barriers— physical, physiological, cellular and cytokine barriers.

Physical Barriers:

• Skin on our body is the main barrier which prevents entry of the microorganisms. 
• Mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital tracts also help in trapping microbes entering our body.

Physiological Barriers:

• The skin and mucous membranes secrete certain chemicals which dispose off the pathogens from the body.
• Acid in the stomach, saliva in the mouth, tears from eyes–all prevent microbial growth.

Cellular barriers:

• Certain types of leukocytes (WBC) of our body like polymorpho-nuclear leukocytes (PMNL-neutrophils) and monocytes and natural killer (type of lymphocytes) in the blood, as well as macrophages in tissues, can phagocytose and destroy microbes.

Cytokine barriers:

• Cytokines (chemical messengers of immune cells) are low molecular weight proteins that stimulate or inhibit the differentiation, proliferation or function of immune cells.
• Virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection.