Section III. T CELLS AND CELLULAR IMMUNITY
ANTIGEN STIMULATED T CELLS
The cell-mediated reaction is initiated by the binding of antigen with an antigen
receptor on the surface of a sensitized T lymphocyte. In recent years, one of the most
vigorous controversies in cellular immunology concerns the nature of receptors used by
T cells to recognize antigen. Although B cells use surface immunoglobulin for this
purpose, studies with antisera against immunoglobulins have failed to identify such
immunoglobulins on the T cell surface. Binding of the T cell receptor may occur directly
or may be mediated by macrophage-bound antigen (Figure 3-3).
Figure 3-3. Simplified model for cell- mediated immunity.