4. T Cell-Antigen Recognition
• Respond to contiguous short amino acid
sequences in proteins-T Cell Epitopes
– Peptides
– Not Native Protein
• T cells do not bind free peptides
• T Cells Recognize a complex of a peptide
fragment bound to the membrane
proteins of cells- Major
histocompatibility complex (MHC)
molecules
5.
6. MHC Molecules
• MHC I
• MHC II
• Physiological function is to present
peptides to T cells
16. MHC Class II Molecules
• Present Peptides to CD4+ T Cells
• Expressed on Dendritic Cells, B
Cells, Macrophages-Professional
Antigen Presenting Cells
21. General Characteristic of Peptide-
MHC Interactions
• Each MHC class I & class II
molecule has a single peptide
binding cleft that can bind many
different peptides
• Anchor Residues
32. Both CD4+ and CD8+ T cells
can recognize antigen only when
presented by a self-MHC
molecule on the membrane of an
antigen presenting cells
CD4+ T Cells-Self MHC II-
Restricted
CD8+ T Cells-Self MHC I-
Restricted
Self MHC Restriction