Chapter 2: Antigens and Antibodies - Vocabulary Flashcards

Vocabulary flashcards covering key terms and concepts from the Antigens and Antibodies lecture notes.

Antigen (immunogen)

Any substance recognized as foreign by the body and capable of provoking a specific immune response (antibody production and/or cell-mediated immunity).

Immunogen

A substance that provokes an immune response.

Self vs non-self (tolerance)

The immune system tolerates self-components and does not attack them; disturbance of tolerance can lead to autoimmune disease.

Autoimmune disease

A condition resulting from loss of tolerance to self-components, causing immune attack on the body’s own tissues.

Epitope (antigenic determinant)

The specific part of an antigen that is recognized by antibodies or T-cell receptors.

Immunoglobulin (Ig)

Antibody protein produced in response to antigen exposure.

IgM

First antibody produced; pentameric structure with 10 antigen-binding sites; large and intravascular; fixes complement; does not cross placenta.

IgG

Most abundant antibody; crosses placenta; opsonizes and activates complement; four subclasses (IgG1-4).

IgA

Antibody found in secretions; alpha heavy chains; important in mucosal immunity; does not fix complement or cross placenta.

IgE

Antibody with epsilon heavy chains; binds mast cells; mediates allergic reactions and defense against parasites; does not fix complement or cross placenta.

IgD

Delta heavy chains; mainly membrane-bound on B cells; low circulating levels; role not fully defined.

Antibody structure: heavy and light chains

Two identical heavy chains and two identical light chains; variable and constant regions; hinge region; antigen-binding sites.

Monoclonal antibodies

Antibodies produced by a single clone of B cells (hybridomas) with identical specificity for one epitope.

Affinity

Strength of attraction between a single antibody-binding site and its epitope.

Avidity

Overall functional strength of all interactions between an antibody and its antigen.

Clonal selection

Proliferation of lymphocytes bearing receptors specific to an antigen; leads to antibody production and memory formation.

Anamnestic response

Secondary immune response; faster and stronger, dominated by IgG with some IgM.