The heavy chain is first generated linked to a common light chain

If the BCR has high affinity for self-antigen, the cell is immediately deleted

Both heavy and light chains are generated at the same time

The BCR is generated by sampling environmental antigens

Antigens from extracellular microbes are generally presented on MHC class I molecules

Cross-presentation is associated with the presentation of extracellular antigen on MHC class I

In the thymus, the site of T cell development, the thymic epithelium primarily expresses MHC class I

Some specialised non-antigen presenting cells, such as lung epithelial cells, express MHC class II

Nucleic acids

Lipids

Sugars

Proteins

1: Eosinophil, 2: Lymphocyte, 3: Neutrophil, 4: Basophil

1: Neutrophil, 2: Lymphocyte, 3: Eosinophil, 4: Basophil

1: Lymphocyte, 2: Basophil, 3: Neutrophil, 4: Eosinophil

1: Basophil, 2: Lymphocyte, 3: Eosinophil, 4: Neutrophil

The TCR will use both CD4 and CD8 in its binding to MHC

The T cell will not progress to a naïve T cell

The TCR can recognise self-MHC molecules plus peptide

The T cell will keep recombing gene elements until a functional TCR is generated

Viral associated material

Microbial surface molecules

Microbial genetic material

Self-MHC presenting microbial peptides

1: Eosinophil, 2: Lymphocyte, 3: Neutrophil, 4: Basophil

1: Neutrophil, 2: Lymphocyte, 3: Eosinophil, 4: Basophil

1: Lymphocyte, 2: Basophil, 3: Neutrophil, 4: Eosinophil

1: Basophil, 2: Lymphocyte, 3: Eosinophil, 4: Neutrophil

Both TCR and BCR can bind conformational antigen epitopes, but only TCRs can bind linear antigen epitopes

Each TCR has double the number of polypeptide (protein) chains than a BCR

Both BCR and TCR bind antigen that is presented by MHC

TCR and BCR both require RAG genes for their generation

To co-localise with peptide:MHC class II to guide it to the surface of the antigen presenting cell

To co-localise and bind to peptides in the endosome to guide their loading into the MHC class II binding cleft

To stabilise the MHC class II structure during the generation of the MHC class II β chain (prior to peptide loading)

To prevent peptides from intracellular proteins being loaded into MHC class II