IMMUNOLOGY

Detailed explanation-1: -Armed effector cytotoxic CD8 T cells are essential in host defense against pathogens that live in the cytosol, the commonest of which are viruses. These cytotoxic T cells can kill any cell harboring such pathogens by recognizing foreign peptides that are transported to the cell surface bound to MHC class I molecules.

Detailed explanation-2: -T-cells have many identical T-cell receptors that cover their surfaces and can only bind to one shape of antigen. When a T-cell receptor fits with its viral antigen on an infected cell, the Killer T-cell releases cytotoxins to kill that cell.

Detailed explanation-3: -B cells create antibodies. B lymphocytes, also called B cells, create a type of protein called an antibody. These antibodies bind to pathogens or to foreign substances, such as toxins, to neutralize them.

Detailed explanation-4: -However, the T-cell receptor differs from the B-cell receptor in an important way: it does not recognize and bind antigen directly, but instead recognizes short peptide fragments of pathogen protein antigens, which are bound to MHC molecules on the surfaces of other cells.

Detailed explanation-5: -activation. … cells, which may be either cytotoxic T cells or natural killer cells, have receptors that bind to the tail portion of the IgG antibody molecule (the part that does not bind to antigen). Once bound, killer cells insert a protein called perforin into the target cell, causing it to swell…