T-Cell or T-Lymphocyte
A (white blood cell) that develops in the bone marrow, matures in the
what appear to be molecules on their surfaces but, unlike ,
these molecules cannot be secreted. This is called a (CD3, and CD4 or CD8).
Works as part of the immune system in the body.
Several distinct T-cell subpopulations are recognized:
(T4 cell, CD4 cell). A class of T-cells which help trigger B-cells to make antibodies against
thymus-dependent . Helper T-cells also help generate cytotoxic T-cells.
(cytoxic T-cells). Cells that kill target cells bearing appropriate antigen within the groove
of an class I molecule that is identical to that of the T-cell.
CD8 cell). The existance of these cells is a relatively recent discovery and hence their functioning
is still somewhat debated. The basic concept of suppressor T-cells is a cell-type that specifically suppresses
the action of other cells in the immune system, notably B-cells and T-cells, thereby preventing the
establishment of an immune response. How this is done is not known with certainty, but it seems that certain
specific antigens can stimulate the activation of the suppressor T-cells. This suppressor effection is thought to be mediated
by some inhibitory factor, secreted by suppressor T-cells. It is not any of the known
. Another fact
that renders the study of this cell-type difficult is the lack of a specific surface marker. Most suppressor
T-cells are CD8 positive as are cytotoxic T-cells.