<unk>  <unk>  is an effector function of IgG and IgM antibodies. When they are bound to surface antigen on target cell (e.g. bacterial or viral infected cell), the classical<unk>  pathway is triggered by bonding protein C1q to these antibodies, resulting in formation of a membrane attack complex (MAC) and target cell lysis.<unk>  system is efficiently activated by human IgG1, IgG3 and IgM antibodies, weakly by IgG2 antibodies and it is not activated by IgG4 antibodies. It is one mechanism of action by which therapeutic antibodies or antibody fragments can achieve an antitumor effect.
Complement-dependent cytotoxicity
Respiratory burst
Alloantigen recognition
Memory T cell inflation
Fragment antigen-binding
Immunoglobulin class switching
Antibody opsonization
Antigen presentation