MRCP UK EXAMINATIONS

Detailed explanation-1: -Prevent viruses from entering cells: Antibodies can bind to viruses that have not yet entered a cell and prevent them from binding and entering. Activate the inflammatory response by activating the complement cascade and by stimulating mast cells to release histamine.

Detailed explanation-2: -The immune system’s three lines of defense include physical and chemical barriers, non-specific innate responses, and specific adaptive responses.

Detailed explanation-3: -Figure: Mechanisms of antibody action: Antibodies may inhibit infection by (a) preventing the antigen from binding to its target, (b) tagging a pathogen for destruction by macrophages or neutrophils, or (c) activating the complement cascade.

Detailed explanation-4: -Three types of antibody interactions with phagocytic cells are seen: direct binding of antibody to the surface of the phagocytic cells (cytophilic antibody), uptake of antigen antibody complexes through the Fc receptor, and uptake of antigen-antibody-complement complexes through the C3b receptor (see Ch.