Answer:
Exogenous Antigen
Step-by-step explanation:
An antigen-presenting cell (APC) is an immune cell that detects, engulfs, and informs the adaptive immune response about an infection. APC present the antigen complexed with with major histocompatibility complexes (MHCs). There are two type of APC: professional APC that presesnt MHCII and non professional APC that present MHCI. Macrophages, Dentritic cells and B cells (before maturation) are examples professional APC cells.
T cells are major cells in cell mediated immunity and B cells are key component for humoral immunity beacuse they are involved in the production of antibodies. There are three types of T cells; helper,cytotoxic and supressive. Foreign antigen presented by professional APC cell with MHC class II are recognized by helper T cells and cytotoxic T cells can recognize endogenous antigen presented on MHC class I. The virus infected cells are destroyed by T cytotoxic cells and T helper cells play a part to activate the cell mediated response and humoral response by stimulating the rapid division of B cells & cytotoxic T cells by producing compounds called interleukins.
T cell can only recognize foreign non viral antigen presented by professional T cells and only T helper cell can induce both cell mediated and humoral immune response.