Question

What is true about T-lymphocytes in mammals : -

• A. There are three main types-cytotoxic T-cells, helper T-cells and suppressor T-cells
• B. These originate in lymphoid tissues
• C. They scavenge damaged cells and cellular debris
• D. These are produced in thyroid

Answer 1

The correct option is A There are three main types-cytotoxic T-cells, helper T-cells and suppressor T-cells

T cells account for about 80% of all lymphocytes. They are named T cells because they mature in the thymus, a gland found in the chest. There are three types of T cell lymphocytes:

• Cytotoxic T cell
• Suppressor T cell
• Helper T cell

Helper T cells are arguably the most important cells in adaptive immunity, as they are required for almost all adaptive immune responses. They not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells. A cytotoxic T cell is a T lymphocyte (a type of white blood cell) that kills cancer cells, cells that are infected (particularly with viruses), or cells that are damaged in other ways. The regulatory T cells formerly known as suppressor T cells are a subpopulation of T cells that modulate the immune system, maintain tolerance to self-antigens, and prevent autoimmune disease.

So, the correct answer is 'There are three main types-cytotoxic T-cells, helper T-cells, and suppressor T-cells'.