To display antibody-bound antigen on its surface to B cells in the germinal centre

To secrete cytokines that promote isotype switching in B cells in the germinal centre

To process and present antigen to follicular helper T cells in the germinal centre

To engulf and remove dead B cells with low affinity isotypes from the germinal centre

A naïve T cell requires co-stimulation to be activated by a dendritic cell

A naïve T cell requires signalling through LFA-1 to activate transcription factors necessary for effector functions

A naïve T cell that binds too strongly with peptide:MHC will be deleted as it is potentially self-reactive

A naïve T cell either requires co-stimulation or very high affinity binding between peptide:MHC to be activated by a dendritic cell

Can be bound by other intracellular molecules

Will remain phosphorylated forever

Can be secreted from the cell to signal other nearby cells

Will translocate to the nucleus to induce gene expression

Cytokines can often produce different effects in different target cells

The cytokine can act directly on the T cell that has generated them

T cells can switch from one T helper subset to another, depending on the pathogen (or peptide) encountered

Different cytokines can often induce the same action in target cells

To allow it to migrate into lymphoid organs

To allow it to migrate towards the pathogen (following the chemokine gradient) to further sample antigen for presentation on MHC

To translocate antigen into the cytosol to facilitate cross-presentation

To engage with the B7 ligand (CD80 & CD86) for co-stimulation

To stabilise the interaction between the T cell and the dendritic cell

To amplify the signal coming from the T cell receptor following peptide:MHC recognition

Bind to the CD4 or CD8 coreceptor after the TCR has bound peptide:MHC

Phosphorylate the ITAM motifs found on the CD3 and ζ (zeta) chains

IgE

IgA

IgM

IgG

It has the capacity to activate complement

It generally generates high affinity antigen receptors

It is expressed on the B cell surface as a pentamer

It is primarily used to neutralise gut bacteria

Reduced presentation in MHC class I molecules

Induction of cross-presentation

Directing peptides to the MHC class II pathway

Virus-induced cell death

To opsonise the microbe to initate complement activation

To activate dendritic cells to upregulate peptide:MHC presentation to T cells

To directly attract neutrophils to the site of infection

To stimulate epithelial cells to secrete cytokines