What is Immunity? | Active and Passive Immunity

Immunity is the ability of the body to defend itself against disease or infection. The immune system has two main parts: innate and adaptive immunity. Innate immunity is the first line of defense against pathogens and consists of cells such as macrophages, neutrophils, mast cells, eosinophils, basophils, dendritic cells, natural killer (NK) cells, and B cells. Adaptive immunity is the second line of defense and involves T and B lymphocytes.

Immunity is the ability of the human body to fight off infections and diseases. This means that our bodies are constantly fighting off bacteria, viruses, parasites, and other microorganisms. Our immune system also protects us from cancerous growths.

Types Of Immunity

There are two types of immunity

Active Immunity

The use of vaccines or antigens, which stimulates the production of antibodies in the body and makes the person immune against the disease or infections, is called active immunity.” Most vaccines consist of a non-virulent, mutant strain of the virus. There are two types of active immunity

1. Artificially induced active immunity: Active immunity is achieved by artificially introducing antigens into the body. So it is called artificially induced immunity

2. Naturally induced active immunity or autoimmune response: sometimes, a person is infected by antigen and becomes ill. In most cases, he survives and developed immunity against that diseases. It is called naturally induced immunity or autoimmune response

Passive Immunity

The injection of antibodies in the form of antisera for making a person immune against disease is called passive immunity. The serum containing antibodies is called antisera. Antigen antibodies complex is formed with in the body. This complex is destroyed by phagocytes. So the patient is saved from complications or sometimes from death

During infection, the cell is not given time for the production of a sufficient level of antibodies. Therefore, antibodies are injected artificially Passive immunity response is immediate. It is not long lasting. After some time, the antibodies are used and the level of antibodies is decreased. So antibodies are not left in the body.