IMMUNITY - INNATE OR ACQUIRED?

 

Introduction

Immunity is the ability of body to resist infection (invasion) caused by foreign agents and to neutralize their effects on body.

What brings about immunity?

Lymphocytes are the cells which bring about the immunity to the body. On the basis of presence or absence of granulocytes, the WBC’s are classified into two categories: Granulocytes & Agranulocytes.

Granulocytes: Consists of 3 types of different cells, namely Eosinophils, Basophils & Neutrophils.

Agranulocytes: Consists of 2 types of cells called, Lymphocytes (B and T Lymphocytes) & Monocytes.

The cell which is responsible for immune response is the part of the agranulocyte WBC.

Different types of Immunities

Innate and acquired are the two types of immunity responsible for the immune system of the human body. However, acquired immunity is divided further into cellular and humoral immunity.

Innate Immunity: The immunity gain by an individual before birth genetically is called innate immunity. Because of innate immunity the particular individual, family, race does not suffer any infectious disease to which they are resistant.

Acquired Immunity: The immunity gain by an individual which is either acquired by exposure to certain infections or artificially acquired. Artificially acquired immunity consists of vaccination or immunization.

How does the acquired immunity work?

Acquired immunity is further divided into humoral immunity & cellular immunity.

Humoral Immunity: Immunity here is due to B-lymphocytes, which are processed in late fetal life in liver & bone marrow.

Mechanism of Humoral Immunity:

Ingestion of foreign particles takes place & formation of memory B cells occur. Also, lymphoblasts form which are converted into plasmoblasts which later form plasma cells. The plasma cell then produce immunoglobulins which attack foreign agents. IgG,IgA,IgM,IgD,IgE are the different immunoglobulins produced by plasma cells .

Cellular Immunity: T-cells are responsible for this immunity. Effective in chronic infections, tumours, grafts. Production of T cell takes place in thymus & specific for particular antigen.

Mechanism of Cellular Immunity:

Foreign particle gets attached to T cell & causes the activation of T cell which leads to formation of many T cells(clone).These are called activated T cells.

There are 4 types of such activated T cells.

Helper T cell: Secrete various chemicals likes Lymphokines. Lymphokines stimulate leucopoiesis, destroy viruses, stimulate antibody production and many more things.

Suppressor T cell: Suppress the function of cytotoxic and helper T cell.

Cytotoxic T cell: Attaches to foreign particles & secretes a enzyme called Perforin which makes a hole into foreign particles through which cytotoxic enzymes are released into the foreign cell, which leads to its destruction.

Delayed Type Hypersensitivity T cell: These cells get activated after few days in relations to certain reactions like Graft Rejection.

Helper & Suppressor T cell are Regulatory T cell.

Cytotoxic & Delayed type T cell are Effector T cell.

 

Various ways in which Antibodies react with Antigens and leads to their destruction.

·         Agglutination of bacteria

·         Lysis

·         Neutralization of toxic sites of organisms

·         Activation of complement system : System of 11 enzymes present in plasma in inactive state. Antigen-Antibody interactions lead to activation of this enzyme system which destroys foreign particles by lysis,opsonization,chemotaxis.

Immunity Boosters

Citrus Fruit : contain Vitamin C which is responsible for boosting immune system.

Red bell peppers: contains almost 3 times as Vitamin C as Florida orange

Broccoli: Antioxidants, Vit A,Vit C,Vit E also boosts immunity

Ginger: High sulfur containing compound called allicin is present which increase immune response

Immunological Variations

Racial variation also contributes to the immune response of the particular individual of that race or species. Likewise there are many human species present on earth but only some of them are immune to certain infections or diseases. For example, Africans are more prone to AIDS(acquired immune deficiency syndrome) as compare to Europeans. Also Lupus(a medical condition in which immune system attacks its own body tissue, an inflammatory disease) is more common in African people than Europeans. However, the newly discovered Novel Corona Virus(SARS-CoV-2) has least affect on the population's of India, Africa & several other countries in Southern Hemisphere but the virus has widely affected the European & North American nations. This is because , the three main killers Tuberculosis, HIV & Malaria have plagued this countries before due to which the people living here are exposed earlier to the medications like chloroquine & hydroxychloroquine. While these medications are substantially used at community level in India, these lead to gain of immune response in relation to SARS-CoV-2 in these countries.