Adaptive Immunity
Response occurs within days of the infection
Highly specific
Highly diverse
Memory component
Major cell types involved: T cells, B cells and antigen presenting
cells
Antigens and Antibodies (CH4)
Antigen – any substance that binds specifically to an antibody or a
T cell receptor (TCR).
Antibody- a protein (immunoglobulin) that recognizes a specific
region (component) of an antigen.
Naïve B cells – membrane-bound
Activated B cells (plasma cells) – soluble (have been secreted)
Immunogen- a substance capable of eliciting an immune response.
Epitope
Epitope – portion of an antigen that reacts with an antibody or T cell
receptor (TCR) also known as an antigenic determinant.
Properties of immunogenicity
Foreignness – molecule must be recognized as foreign.
tolerance – unresponsiveness to self antigens.
Properties of immunogenicity
Molecular size –correlation between size an immunogenicity.
Bigger is better – i.e. macromolecules
Chemical composition/complexity
Properties of immunogenicity
Processing and presentation – important for T cell responses, ability
of the antigen to be phagocytosed and processed.
Large
Insoluble
Aggregates
Immunogenicity
Immunogenicity also depends on:
Host factors
Dosage
Route of entry
Recall:
Jerne, Talmadge & Burnet – clonal selection theory
Antibody Structure
Antibody-Mediated Effector Functions
Opsonization
Assist/activate complement system
ADCC
Marasco and Sui, 2007
Antibody-Mediated Effector Functions
Opsonization – promotion of phyagocytosis of antigens by
macrophages and neutrophils.
Fc receptor (FcR)
Metzger 1994
Antibody-Mediated Effector Functions
Activate and assist complement system
Antibody-Mediated Effector Functions
ADCC – Antibody-dependent cell-mediated cytotoxicity