L7 Flashcards
Antibodies
Contribute to immune responses via neutralization, opsonization, agglutination, complement activation, ADCC, and degranulation
IgM
First antibody isotype produced, efficient in complement activation and agglutination
IgG
Functions in opsonization, complement activation, neutralization, and mediates ADCC
IgA
Provides mucosal immunity by neutralizing pathogens in secretions
IgE
Involved in allergic reactions and defense against parasites through degranulation
IgD
Found on mature B cells and aids in activating basophils and mast cells
Fc receptor
Protein on immune cells binding the Fc region of antibodies to mediate effector functions
Macrophages and neutrophils
Express Fc_ receptors for antibody-mediated phagocytosis
NK cells
Express Fc_RIII for antibody-dependent cell-mediated cytotoxicity (ADCC)
Mast cells and eosinophils
Express Fc_RI for degranulation in allergic and parasitic responses
Complement activation by IgM
More efficient than IgG due to pentameric structure binding multiple C1q molecules
Agglutination
Process where antibodies (e.g., IgM, IgA) cause pathogens to clump, enhancing clearance
Viral neutralization
Antibodies bind viral surface proteins, preventing entry into host cells
Antibody-dependent cell-mediated cytotoxicity (ADCC)
Antibodies tag cells for killing by NK cells or other immune cells
Cross-presentation
APCs present extracellular antigens on MHC class I to activate cytotoxic T cells
Cytotoxic T lymphocytes (CTLs)
Kill infected or tumor cells via perforin/granzyme pathways or Fas/FasL interaction
Natural Killer (NK) cells
Target cells lacking MHC class I, killing them via cytotoxic granules
Natural Killer T (NKT) cells
Hybrid cells contributing to immune regulation and cytotoxic responses
Perforin
Protein forming pores in target cell membranes to allow entry of granzymes
Granzyme
Protease inducing apoptosis in target cells via activation of caspases
Caspase-3
Executioner caspase activated during apoptosis in target cells by CTLs or NK cells
