Immunity is our body’s ability to destroy the pathogens or other foreign material (which causes harm to our body) and protect us from certain infectious disease. This immune system evolved to protect multicellular organisms from pathogens. The immune response relies on the recognition molecule that can be germline encoded or randomly generated. The fully functional immune system involves so many organs (such as lymph node, bone marrow), cells (such as Lymphocytes, monocytes, macrophages etc), molecules and pathways (like complement pathway) in such an interconnected and sometimes circular process. The study about immune system is known as immunology.
In vertebrate immune response can be divided into two interconnected arms of immunity:
- INNATE IMMUNITY: It is non-specific natural resistance to the pathogenic infection, which an individual posse in born. It acts without any previous knowledge and so, its specificity is very low and its lack the ability to distinguish a microbe from another. Innate immunity includes physical, chemical, and anatomical barriers that prevent infection. These barriers are provided by the cells layer of the skin, mucosal tissues (present in the gastrointestinal tract, respiratory tract, urinary tract etc), and glandular tissues (such as tissue of salivary and mammary gland). Phagocytosis, Fever, Inflammation are also the principal component of innate immune response.
- ADAPTIVE IMMUNITY: The immunity with previous knowledge about the pathogenic substances which is gained or acquired through experiences of an individual during its life is known as adaptive or acquired immunity. It shows antigenic specificity and has high degree of diversity and it consists of self and non-self, recognition.
There are some molecules which help to trigger our immune response (mainly acquired immune response) to a particular pathogenic substance is known as immunogen. These are mainly inactive or attenuated part of the pathogenic materials, which enters into our̥ body by many processes mainly by vaccination.