CHAPTER 3 – ANTIGEN CAPTURE AND PRESENTATION TO LYMPHOCYTES
(FROM THE TEXT)
1. The induction of immune responses to the protein antigens of microbes depends on a
specialized system for capturing and displaying these antigens to naïve T cells.
Microbes and microbial antigens are captured by professional APCs (e.g. dendritic cells
and macrophages) and transported to regional lymph nodes. The protein antigens of the
microbes are displayed by the APCs to naïve T lymphocytes that recirculate through the
2. Molecules encoded in the MHC perform the function of displaying peptides derived
from protein antigens.
3. Proteins that are ingested by APCs from the extracellular environment are
proteolytically degraded within the vesicles of the APCs and the peptides that are
generated bind to the clefts of newly synthesized class II MHC molecules. Class II MHC
molecules are recognized by CD4, because of which CD4+ helper T cells are specific for
class II MHC-associated peptides that are derived mainly from extracellular proteins.
4. Proteins that are produced by microbes living in the cytoplasm of infected cells, are
degraded by proteasomes, transported into the ER by TAP, and bind to the clefts of