Immunity and its types: Immunity is the ability of the body to defend itself against disease-causing organisms. Everyday our body comes in contact with several pathogens, but only a few results into diseases. The reason is, our body has the ability to release antibodies against these pathogens and protects the body against diseases. This defence mechanism is called immunity.

• Innate Immunity or Natural or Non-specific Immunity: Innate immunity refers to the body’s defence system. This type of immunity is present in an organism by birth. This is activated immediately when the pathogen attacks. Innate immunity includes certain barriers and defence mechanisms that keep foreign particles out of the body. It is a long-term immunity in which our body produces the antibodies on its own. Our body has few natural barriers to prevent the entry of pathogens.

• Acquired Immunity or Adaptive Immunity: Acquired immunity or adaptive immunity is the immunity that our body acquires or gains over time. Unlike the innate immunity, this is not present by birth. It is specific and mediated by antibodies or lymphocytes which make the antigen harmless. The main function of acquired immunity is to relieve the victim of the infectious disease and also prevent its attack in future.

Cells Involved in Innate Immunity

• Phagocytes: These circulate through the body and look for any foreign substance. They engulf and destroy it defending the body against that pathogen.

• Macrophages: These have the ability to move across the walls of the circulatory system. They release certain signals as cytokines to recruit other cells at the site of infections.

• Mast Cells: These are important for healing wounds and defence against infections.

• Neutrophils: These contain granules that are toxic in nature and kill any pathogen that comes in contact.

• Eosinophils: These contain highly toxic proteins that kill any bacteria or parasite in contact.

• Basophils: These attack multicellular parasites. Like the mast cells, these release histamine.

• Natural Killer Cells: These stop the spread of infections by destroying the infected host cells.

• Dendritic Cells: These are located in the tissues that are the points for initial infections. These cells sense the infection and send the message to the rest of the immune system by antigen presentation.

Cells Involved in Acquired Immunity

• B-cells: They develop in the bone marrow. These cells are activated on their encounter with foreign agents. These foreign particles act as foreign markers. The B-cells immediately differentiate into plasma cells which produce antibodies specific to that foreign particle or so-called antigen.

• T-cells: They originate in the bone marrow and develop in the thymus. T-cells differentiate into helper cells, cytotoxic cells, and regulatory cells. These cells are released into the bloodstream. The cytotoxic T-cells kills the cancer cells. Regulatory T-cells regulate immune reactions.

Difference between Innate Immunity and Acquired Immunity

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By Team Learning Mantras