Immunity

Unbeknownst to us, our body fights against harmful viruses and pathogens every day and help us to stay safe from diseases. Consequently, immunity can be defined as the ability of an organism to fight against diseases and infections.

Immunity can be classified into two groups – (i) innate immunity, and (ii) acquired immunity. The two types of immunity have been discussed in detail below – 

Innate Immunity

All organisms possess some disease resistance ability that they have inherited from their parents or have gained naturally. This is known as innate immunity. It is our body’s first line of defence against the disease-causing virus and pathogens. 

However, it does not have any immunological memory, which means it cannot remember antigens. Therefore, it initiates the same level of response every time it encounters the same antigen and viruses. 

Innate immunity can be categorised based on individual, racial and species. These types of natural immunity is explained below -

  1. Individual immunity – Sometimes, individuals belonging to the same race and who have been exposed equally to the virus, pathogens or worms can show a different level of immunity to a disease or infection. 

          

         This can be due to any number of reasons. People who are exhibiting higher levels of immunity may have been exposed to the virus before, and their body has developed resistance against it. Other factors such as health, age and hereditary traits can also be responsible for individual immunity. 

  1. Racial immunity – When one race is immune to a certain disease, and another race is susceptible to it, it is referred to as racial immunity. Again, factors such as genetic make-up, food habits, climate condition play an essential part in determining racial immunity.

  2. Species immunity – When a disease attacks a species only and another species is entirely immune to it, it is known as species immunity. For instance, only human beings are susceptible to ailments such as measles, mumps, HIV, etc. Animals cannot contract these diseases.

Innate immunity makes use of different types of barriers to protect against diseases. These include cytokine, cellular, physiological, and physical. 

Adaptive Immunity 

When organisms develop immunity against certain diseases by developing antibody within themselves, it is referred to as adaptive or acquired immunity. The main difference between innate and acquired immunity are as follows – 

  • Immunological memory – Acquired immunity has immunological memory while innate immunity does not. Which means once it is exposed to a virus, it can retain a memory of the same. Hence, when it confronts the same virus for the second time, it responds much more quickly and efficiently.

  • Specificity – Specificity describes the main difference between the two types of immunity. Innate immunity provides general protection against a vast array of viruses, antigens, pathogens and the like; adaptive immunity only provides immunity against a specific type of antigen. 

  • Ability to distinguish between self and non-self – The antigens that are already present in the cells of our body are called self-antigens. On the other hand, antigens that originate outs the body are non-self antigens. 


Our immune system must be able to differentiate between the two; otherwise, it will start attacking and resisting the self-antigens, which can have severe health consequences. The adaptive immune system can differentiate between the two. 

Now that you know what is Acquired immunity, you should also know that it is of two types – 

  1. Active immunity – When an organism’s immune system is actively involved in the formation of antibodies and production of immune-competent cells, it is called active immunity.

  2. Passive immunity – In case of passive immunity, antibodies and immune-competent cells are transferred from one organism to another to increase resistance against a pathogen.

Adaptive immunity is carried out via B lymphocytes (B cells) and T lymphocytes (T cells). Immune response by B cells is known as humoral immunity. Similarly, WH-immunity facilitated by T cells is called cellular immunity.  

You can also refer to our innate and acquired immunity notes to have a more detailed understanding of how these they work in different ways to provide protection against viruses and antigens.

Moreover, you can download the study guide on immunity and its types as pdf via Vedantu’s application to study according to your convenience.

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FAQ (Frequently Asked Questions)

1. What are the two types of acquired immunity?

Two types of acquired immunity are active and passive immunity. Active immunity helps in the formation of antibodies and production of immune-competent cells. Passive immunity transfers immune-competent cells from one organism to another to increase resistance against a pathogen.

2. Which part of our body manufactures antibody?

B lymphocytes or B cells manufacture antibodies. Immune response by B cells is also known as humoral immunity.

3. What are the two types of immunity?

 The two main types of immunity are innate and acquired.