Adaptive ImmunityResponse 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-boundActivated B cells (plasma cells) – soluble (have been secreted)

Immunogen- a substance capable of eliciting an immune response.

EpitopeEpitope – portion of an antigen that reacts with an antibody or T cell receptor (TCR) also known as an antigenic determinant.

Properties of immunogenicityForeignness – molecule must be recognized as foreign.

tolerance – unresponsiveness to self antigens.

Properties of immunogenicityMolecular size –correlation between size an immunogenicity.

Bigger is better – i.e. macromolecules

Chemical composition/complexity

Properties of immunogenicityProcessing and presentation – important for T cell responses, ability of the antigen to be phagocytosed and processed.

LargeInsolubleAggregates

ImmunogenicityImmunogenicity also depends on:

Host factorsDosageRoute of entry

Recall:Jerne, Talmadge & Burnet – clonal selection theory

Antibody Structure

Antibody-Mediated Effector FunctionsOpsonizationAssist/activate complement systemADCC

Marasco and Sui, 2007

Antibody-Mediated Effector FunctionsOpsonization – promotion of phyagocytosis of antigens by macrophages and neutrophils.

Fc receptor (FcR)

Metzger 1994

Antibody-Mediated Effector FunctionsActivate and assist complement system

Antibody-Mediated Effector FunctionsADCC – Antibody-dependent cell-mediated cytotoxicity