T-cell

T-cells (AKA T-lymphocyte) are white blood cells involved in cell-mediated immunity along with other cells such as NK cells, etc. T-cell maturation (positive and negative selection) takes place within the Thymus (Remember T for T-cell and T for Thymus). Main subtypes of T-cells include, T-helper cells (CD4+) and cytotoxic T-cells (CD8+).