Antigens and Antibodies Lecture Notes

Flashcards covering key vocabulary and definitions related to antigens and antibodies.

Immunogen

A macromolecule capable of triggering an adaptive immune response and then reacting with the antibodies produced.

Antigen

Any substance that may be specifically bound by an antibody molecule or T-lymphocyte receptor.

Hapten

A lower molecular weight molecule that can bind to an antibody but must be attached to a macromolecule as a carrier to stimulate a specific immune response.

Epitope

The part of an antigen that specifically binds with an antibody or T-lymphocyte receptor.

Major Histocompatibility Complex (MHC)

A set of molecules displayed on cell surfaces that are crucial for the immune system's recognition of foreign molecules.

MHC class I

Presents endogenous antigens to CD8+ T cells and is found in most nucleated cells.

MHC class II

Presents exogenous antigens to CD4+ T cells and is primarily found on B-cells and APCs.

Autoantigens

'Self' antigens that can produce autoantibodies in the body.

Blood Group Antigens

Antigens found in tissues, blood cells, and fluids that are important for transplantation, paternity testing, and forensic medicine.

Immunoglobulin

Specific proteins that function as antibodies, isolated in the gamma globulin fraction.

IgM

The first antibody in an immune response that activates the classical complement pathway.

IgG

The predominant antibody in plasma that mediates neonatal immunity through maternal transfer.

IgA

An antibody that defends external body surfaces and activates the alternative complement pathway.

Antibody Structure

Typically consists of heavy and light chains, with specific regions for antigen binding.

Monomer

A single unit of antibody structure, commonly seen in IgG, IgD, and IgE.

Pentamer

A five-unit structure of antibodies, specifically seen in IgM.

Dimer

A two-unit structure of antibodies, specifically seen in secretory IgA.