Question

Type of cells in cell_mediated immune response

Answer 1

Cell mediated immunity involves the following types of cells:

1. Antigen specific T - Lymphocytes

The T Lymphocytes are of four types:

i) Helper T cells

ii) Cytotoxic T cells

iii) Delayed Hypersensitivity T cells

iv) T suppressor cells

2. Nonspecific cellular components are:

i) Activated macrophages

ii) Natural killer cells

1.  Antigen specific T-Lymphocytes: It is a type of lymphocyte that plays a central role in cell mediated immunity.

T cells can be distinguished from other lymphocytes such as B cells by the presence of a T cell receptor on the cell surface.

There are four types of T-cells involved in cell mediated immune response. They are as follows:

i) Helper T cells: It is a type of T cell that influence or controls the differentiation or activity of other cells of the immune system. They recognize antigen on the surface of antigen presenting cells. Helper T cells activate macrophages and induce formation of cytotoxic T cells. They also stimulate B cells to produce antibodies.

ii) Cytotoxic T cells: These T cells destroy the target cells. They recognize antigens on the surface of cells. They kil the host cells that are infected with viruses and bacteria. They recognize and kill cancer cells and transplanted tissue. These cells releases two types of proteins viz. perforin and granzymes.

iii) Delayed Hypersensitivity T cells: These involve mostly T helper and a few cytotoxic T cells that are involved in some allergic reactions and rejection of transplanted tissue.

iv) T suppressor cells: These are type of T cells that can suppress antibody production by other lymphoid cells. They maintain immune system homeostasis and tolerance to self antigens.

2. Nonspecific cellular components are:

i) Activated macrophages: These are large phagocytic cells found in stationary form in the tissues or as a mobile white blood cells especially at the site of infection. They enhance the ability of cells to eliminate intracellular bacteria, virus infected and cancerous cells.

ii) Natural killer cells: These are the lymphocyte cells which destroy virus infected and tumor cells. These are not specific so they dont require antigen stimulation.