NEET BIOLOGY

Detailed explanation-1: -T cells have dual specificity, so they recognize both self-major histocompatibility complex molecules (MHC I or MHC II) and peptide antigens displayed by those MHC molecules.

Detailed explanation-2: -When the perfectly shaped virus antigen on an infected cell fits into the Killer T-cell receptor, the T-cell releases perforin and cytotoxins. Perforin first makes a pore, or hole, in the membrane of the infected cell. Cytotoxins go directly inside the cell through this pore, destroying it and any viruses inside.

Detailed explanation-3: -T Cells Recognize Foreign Peptides Bound to MHC Proteins As discussed earlier, both cytotoxic T cells and helper T cells are initially activated in peripheral lymphoid organs by recognizing foreign antigen on the surface of an antigen-presenting cell, usually a dendritic cell.

Detailed explanation-4: -The initial encounter with specific antigen in the presence of the required co-stimulatory signal triggers entry of the T cell into the G1 phase of the cell cycle; at the same time, it also induces the synthesis of IL-2 along with the chain of the IL-2 receptor.