In type II hypersensitivity reactions, which mechanism leads to tissue damage?

Correct option is A

Ans: (a) Antibody-mediated cell destruction Sol. In type II hypersensitivity reactions, tissue damage is primarily caused by antibody-mediated cell destruction. This occurs when antibodies (typically IgG or IgM) bind to antigens on the surface of cells, leading to the activation of immune responses that destroy the cells. This process can involve complement activation, phagocytosis, or ADCC (antibody-dependent cellular cytotoxicity), but the primary mechanism of tissue damage is due to antibodies binding to the target cells, marking them for destruction.
Explanation of each option:
· (a) Antibody-mediated cell destruction: Correct answer. Type II hypersensitivity is characterized by antibodies (mainly IgG or IgM) binding to the surface antigens of cells, leading to their destruction by complement activation or phagocytosis.
· (b) Complement activation: While complement activation does play a role in type II hypersensitivity, it is not the primary mechanism of tissue damage. It is a downstream effect after antibody binding to the target cells.
· (c) Opsonization and phagocytosis: Opsonization refers to the process by which antibodies or other molecules mark a pathogen or cell for destruction by phagocytes. This can occur in type II hypersensitivity, but again, antibody-mediated cell destruction is the central mechanism.
· (d) Deposition of immune complexes: This is more characteristic of type III hypersensitivity, not type II. In type III, immune complexes (antigen-antibody complexes) deposit in tissues, causing inflammation and damage.