IMMUNOLOGY SERIES-PART 2- CLASSIFICATION OF IMMUNITY & INNATE IMMUNITY

The previous article gave a brief introduction to immunity, the internal force protecting us from several hazards. This article will be on the classification of immunity.

This is the classification chart for immunity. Immunity can be briefly classified as two, innate immunity and the acquired immunity. Innate immunity also known as natural immunity and native immunity is the one that has been bestowed to us. This type of immunity is present from birth till death. The following are the other names of innate immunity:-

  • Natural immunity
  • Native immunity
  • Non-specific immunity

Innate immunity is the resistance to infections which an individual possesses due to their genetics. Also, there are other factors that can decide native immunity.

Species- the native immunity which is present within everyone is species-specific. The meaning is that humans have resistance to a specific set of infections and the plants have resistance to another specific set of infections. This is the reason for which humans do not get affected by plant diseases and vice versa.

Race- race refers to the group of people from several parts of the world. People in one part of the world may be resistant to a particular disease when compared to others. This can also depend on the environmental conditions and other factors in which people reside. A suitable example for this is a study that shows that the Negroid species (of African origin) in the US are more resistant to tuberculosis when compared to the Caucasian species (European origin).

Individual- people having a similar genetic constitution may have the same resistance/non-resistance to infections. A study shows that twins have the same level of resistance and non-resistance to several diseases.

The innate immunity is long-lasting, non-specific, and has a good memory. The term memory will be explained while introducing the immune cells. Innate immunity forms the first line of defence in our body. This immunity primarily focuses on providing a barrier to the body and destroying the microbes and pathogens, irrespective of their type. Hence the innate immunity is known as non-specific immunity. There are specified cells that perform this activity and the process is known as phagocytosis. More details will be provided in the next article.

The innate immunity can be comprised of four namely. These can be known as the barriers of innate immunity:-

  • Physical
  • Physiological
  • Cellular
  • Cytokine

The physical type includes the mechanical barriers mostly present in the openings of the body (eye, nose, mouth, ears, genitals, and skin) which prevent the entry of microbes through several mechanisms.

The physiologic type includes the secretions of which help in kicking out the pathogens. These include sweat, highly acidic stomach acid, saliva, sebaceous glands, earwax, and mucus, and so on. These secretions mostly trap the pathogens and prevent them from reaching inside.

The cellular type includes some arrangements made to prevent microbe entry. For example, the wall of the blood vessels is tightly attached with each other ensuring that there is no gap hence preventing the entry of microbes.

The last type includes cytokines. The cytokines are a broad group of signaling proteins that take an important part in immunity. These molecules help in regulating the immune response.

The next article deals with the 6 mechanisms of innate immunity. Till that

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