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Flashcards in B-cells & Antibodies Deck (8)
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Primary immune response

Occurs upon first exposure to antigen

IgM is initially detected in the serum and levels then rapidly decrease as the switched antibody response takes over

The switched antibody response occurs after 4-7 days, during which, illness will be apparent


Secondary immune response

Occurs upon subsequent exposure to the same antigen

The IgM response occurs as usual, but the switched antibody response takes over much more rapidly and reaches a higher titre

During this response, illness is not apparent


Functions of antibody

-Neutralisation of toxins
-Opsonisation of pathogens
-Activation of complement
-Mediation of antibody-dependent cell-mediated cytotoxicity


Class switching

The process by which the antibody class changes

Determined by the cytokine environment and mediated by T-helper cells

Changes occur in the Fc region only; so antibody specificity is unchanged


T-dependent B-cell activation

T-dependent antigens require help from T-cells to complete activation

The antigen binds to the BCR and this complex is recognised and internalised and degraded

The peptide antigen is then presented on MHC class II molecules to recruit T-helper cells


Type I T-independent B-cell activation

Type I T-independent antigens generate a polyclonal response without needing reference to a specific receptor

Examples include TLRs


Type II T-independent B-cell activation

Type II T-independent antigens are large with repeating structures

These antigens bind multiple receptors on the same cell and receptor cross-linking leads to activation of the cell

Memory B-cells are not formed from this type of activation


Lymphocyte diversity

The genes encoding the BCR are rearranged during development

This is carried out by recombination activating genes (RAG)