What is true about T-lymphocytes in mammals:
- There are three main types-cytotoxic T-cells, helper T-cells and suppressor T-cells
- These originate in lymphoid tissues
- They scavenge damaged cells and cellular debris
- These are produced in thyroid
The Correct Option is A
Solution and Explanation
T-lymphocytes, or T-cells, play a critical role in the immune system. Among T-cells, there are indeed three main types:
- Cytotoxic T-cells (also known as killer T-cells) that are responsible for destroying infected or abnormal cells.
- Helper T-cells that coordinate immune responses and activate other immune cells.
- Suppressor T-cells (also known as regulatory T-cells) that help regulate and suppress excessive immune responses to prevent autoimmune reactions.
The other statements are not accurate:
- T-lymphocytes originate in the bone marrow, not lymphoid - tissues.
- They are involved in immune responses but do not scavenge damaged cells or cellular debris.
- They are not produced in the thyroid.
So, the correct option is (A): There are three main types-cytotoxic T-cells,helper T-cells and suppressor T-cells
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Concepts Used:
Types of Immunity
Immunity can be defined as the body's ability to guard itself against disease-causing organisms. In other words, it is the ability to resist infection by the action of particular antibodies. Our body has the ability to produce antibodies against pathogens and defend itself from diseases; therefore, we may come in contact with several viruses every day, but not get ill. This defense mechanism is therefore known as immunity.
The two major types of immunity are:
- Innate Immunity or Non-specific Immunity
- Acquired Immunity or Adaptive Immunity
Innate immunity
The immunity, which is present in an organism by birth is called innate Immunity. Innate immunity refers to the body’s defence system. For example, the skin, the barrier of the human body functions by protecting the entry of germs and other disease-causing pathogens.
Adaptive immunity
An individual acquires immunity after birth, hence is called adaptive or acquired immunity. Adaptive immunity develops throughout our lives. We acquire adaptive immunity when we are exposed to infectious diseases and allergies or when we are immunized against them with vaccines.
Passive immunity
Passive immunity is developed by antibodies that are produced outside the body. This immunity lasts for a short time. For example, antibodies present in a mother’s breast milk provide a baby with temporary immunity against the diseases.
Active Immunity
Active immunity is a type of adaptive immunity, which is developed due to the production of antibodies in one’s own body. This type of immunity occurs when we are in contact with the pathogen or its antigen.