They both migrate to the same regions within a lymph node

There is strong adhesion during the interaction of TCR with the peptide:MHC

They confirm their antigen specificity before the T cell differentiates into a T helper cell

They are able to enter the B cell follicle to facilitate the germinal centre reaction

CD28 binds B7-1 and B7-2 (CD80 & CD86) with significantly greater affinity than does CTLA-4

Only CD28 binds the costimulatory ligands B7-1 and B7-2 (CD80 & CD86) expressed on professional antigen-presenting cells

CD28 is constitutively expressed on naïve T cells, whereas CTLA-4 is expressed on activated T cells

CD28 is important for delivering “signal 1” for T cell activation, whereas CTLA-4 is important for delivering “signal 2”

Proliferate to expand CD4 T cell numbers

Migrate to the B cell zone to activate antigen specific B cells

Secrete IL-2

Increase expression of TCR on its surface

Heavy chain

Light chain

Antigen binding site

Fc region

Is present in breast milk

Is found as a pentamer

Is transported across the placenta

Is a good activator of complement

It can bind to a range of epitopes on the toxin antigen and effectively block the toxin’s action

It is collecting toxin and transferring it to nearby phagocytes for destruction

It will bind with low affinity to be able to sample as much toxin as possible

It is effectively removing toxin from its surroundings

Poly-Ig receptor

Complement receptor

B cell receptor

Fc alpha (Fcα) receptor

IL-4 produced by TH2 cells drives IgE production

TH2 cells will recognise helminth peptides presented by MHC class I on the surface of mast cells

Cytokines produced by TH2 cells directly cause mast cell degranulation

IL-4 and IL-5 will cross-link receptors on mast cells leading to degranulation

TH2 and TH17

TH2

TH1 and TH2

TH17

CD8 cytotoxic T cells only

CD4 T helper cells and CD8 cytotoxic T cells

CD4 T helper cells and antibodies

CD4 T helper cells only