Question

QUESTION 16 Acquired Immunodeficiency Syndrome (AIDS) invades which type of T cell?

Cytotoxic T cells Helper T cells Regulatory T cells Memory T cells

Answer 1

Acquired immunodeficiency syndrome (AIDS) is caused by the virus HIV(human immunodeficiency virus).

HIV infects white blood cells in the body's immune system called T-helper cells.

The virus attach and fuses itself to the T-helper cell and changes its genetic material .so it can enter the nucleus of the T-helper cell and take control of its DNA. Replicate the virus genome inside the T helper cell . Such infected T-helper cells produces more HIV proteins and then release more number of HIV particles into the blood. This is how the virus multiplies in the body and hence it is called the HIV lifecycle.

What are T cells and their different types?

T cells are a type of white blood cells (WBC) and central regulators of immune response. they mature inside thymus gland (hence the name) and differentiate into various types namely cytotoxic T cells, helper T cells, regulatory T cells and memory T cells.

Cytotoxic T lymphocytes (CTL or Tc cells)- they are part of cell mediated immunity and perform killing effects. They usually target virus or bacterial infected cells or cancerous cells

Helper T cells (Th cells)- they secrete low molecular weight cytokine proteins . They activate B cells (to produce antibodies), macrophages and Tc cells. They have many subsets such as Th1, Th2, Th17, Tfh (follicular helper cell)

Regulatory T cells (T regs)- specialized subpopulation of T cells that act to suppress immune response thereby maintaining homeostasis and self-tolerance. Hence also called as suppressor T cells.

Memory T cells- they are the subsets of both antigen specific Tc and Th cells which are once exposed to antigen, thus remains for long term as a memory even after the infection is treated. They convert into effector cells when the particular infection attacks again.