T cell differentiation, maturation and activation
T CELL
T-cell Receptor
The T cell receptors constitute of two polypeptide chains and have
one binding site for antigen. The commonly found T cell receptors
have alpha and beta chain and few of the T cell receptors are
composed of gamma and beta. The chains are held together by
disulphide bonds and have a variable and constant region.
Maturation
The immature T cells that move into the thymus from the bone
marrow are known as themocytes. The four region of thymus
contribute to the development of themocytes. First the development of
double negative themocytes into double positive themocytes takes
place (CD4+CD8+). During the maturation of the themocytes the
positive selection takes place where the themocytes that do not react
with the MHC class I and II are eliminated through apoptosis. After
this the cells that survive undergo negative selection in the medulla of
the thymus. The themocytes that strongly interact with the self-
antigens are eliminated by cell death. The cells that are able to survive
the positive and negative selection are able to leave the thymus as
mature naïve T cells.
Activation
The activation of CD4+ T cells results due when the T cell receptor
and a co-stimulatory molecule interact with each other. The CD4+
activation aids to the activation of CD8.
T CELL
T-cell Receptor
The T cell receptors constitute of two polypeptide chains and have
one binding site for antigen. The commonly found T cell receptors
have alpha and beta chain and few of the T cell receptors are
composed of gamma and beta. The chains are held together by
disulphide bonds and have a variable and constant region.
Maturation
The immature T cells that move into the thymus from the bone
marrow are known as themocytes. The four region of thymus
contribute to the development of themocytes. First the development of
double negative themocytes into double positive themocytes takes
place (CD4+CD8+). During the maturation of the themocytes the
positive selection takes place where the themocytes that do not react
with the MHC class I and II are eliminated through apoptosis. After
this the cells that survive undergo negative selection in the medulla of
the thymus. The themocytes that strongly interact with the self-
antigens are eliminated by cell death. The cells that are able to survive
the positive and negative selection are able to leave the thymus as
mature naïve T cells.
Activation
The activation of CD4+ T cells results due when the T cell receptor
and a co-stimulatory molecule interact with each other. The CD4+
activation aids to the activation of CD8.
