What is T cell ?

Definition of  T cell :

T cells or T lymphocytes are a type of lymphocyte (itself a type of white blood cell) that play a central role in cell-mediated immunity. They can be distinguished from other lymphocytes, such as B cells and natural killer cells (NK cells), by the presence of a T-cell receptor (TCR) on the cell surface. The T in T cell stands for thymus because they mature in the thymus (although some also mature in the tonsils). There are several subsets of T cells, each with a distinct function.

     Fig 1 : Scanning electron micrograph ofT Cell (right), a platelet(center) and a red blood cell (left) 

The different types of  T cells are:

• Helper T cell
• Natural killer T cell
• Suppressor T cell
• Cytotoxic T cell
• Memory T cell
• Regulatory T cell
• Gamma delta T cell