IMMUNE SYSTEM CELLS

Adaptive and Innate Immune System: Cells Structure & Function

Adaptive and Innate Immune System: Cells Structure & Function

Type of Immune System

Function

Structure

Adaptive Immune System

The two main types of cells of the adaptive immune system are:

T cells

B cells

White blood cells also called as lymphocytes play a vital role in immune system of the body. The acquired immune system has two types of lymphocytes called the T cells (80%) and B cells (10-15%).

Source: www.people.eku.edu

T cells (Cell mediated immunity)

The three types of T cell lymphocytes are:

Cytotoxic T cells

Suppressor T cells

Helper T cells

T cells function by two means within the body, either they discharge the substances directly into blood and also by signaling the B cells through direct contacts.

T cells are also responsible to generate signals for the activation and growth of B cells.

They also activate the cells which are responsible to eat the foreign substances which enter in the body.

During an infection of viral origin T cells causes the stimulation of Cytotoxic T cells.

Signals growth in other types of T cells, macrophages and eosinophils.

T cells surface is covered by many receptors which signal the functions called the T cell receptors. The T cell receptors are composed of constant and variable domains with only one binding site. The T cell receptors are always joined to the membrane by trans-membrane domains.

Source: www.courses.washington.edu

Helper T cells

Helper T cells are the most densely populated type of T cells present in the body. They mainly regulate most of the immune system activities and help maintaining the immunity in several manners. The mechanism through which they act is the release of chemical substances called Lymphokines, which stimulate the growth of different types of T cells and controls the immunity of the body. Helper T cells also stimulate the maturation and activity of B cells.

Source: www.niaid.nih.gov

Cytotoxic T cells

Cytotoxic T cells play a vital role in protection against viral infections, in the rejection of organ and tissue grafts and in certain types of tumors. The function and activity of cytotoxic T cells is based upon antigen presenting cells and on the helper T cells. After activation they release a chemical called perforin and certain enzymes which cause the destruction of target cells.

To destroy the target the cytotoxic T cell first attaches itself to the cell, and then releases the destructing substances directly on the cell. In this way there is no damage to the neighbor cells. The substance causes the self destruction of the cell and any viral particles present within the cell will also be destroyed. As a result of this the viral particles will not be released out of the cell. After the destruction of target the cytotoxic T cell leaves the target cells.

Suppressor T cells

Suppressor T cells suppress the function of both cytotoxic and helper T cells. They act as the main regulators for other types of cells of the immune system. As a result of this action other cells are prevented from excessive damage. They also play a major role and prevent ...