Final answer:
The two major classes of lymphocytes mediating cellular immunity have CD proteins on their surface, with the most common markers being CD4 and CD8. T cells are identified by these markers, with CD4 markers on Helper and regulatory T cells, and CD8 markers on cytotoxic T cells.
Step-by-step explanation:
The two major classes of lymphocytes that mediate cellular immunity are based on the presence of surface proteins called cluster of differentiation (CD) proteins. The most common are those with the CD4 and CD8 markers. All T cells produce CD molecules, which are cell surface glycoproteins used to identify and differentiate various types of white blood cells. CD4 and CD8 are the most important CD molecules, with CD4 being characteristic of Helper T cells and regulatory T cells, while CD8 is a marker for cytotoxic T cells.
T lymphocytes recognize antigens based on a two-chain protein receptor. The most common and important of these receptors are the alpha-beta T cell receptors. Hence, the lymphocytes responsible for cellular immunity include different types of T cells characterized by these CD markers.