Chapter 3: Cellular Immunity
Which division of the immune system involves presentation of antigens to T cells?
What is the term for cells that present antigens to T cells?
antigen-presenting cells (APCs)
What are the cell surface molecules that present antigens to cells of the immune system?
major histocompatibility complex (MHC)
Which class of MCH is the major determinant of “self,” found in all nucleated cells in the human body?
MCH class I (MCH I)
Which class of MCH is found on APCs, which engulf and digest pathogens and present peptide antigens?
MCH class II (MCH II)
What type of T cells recognize antigens presented by MCH I molecules?
CD8+ (cytotoxic) T cells
What type of T cells recognize antigens presented by MCH II molecules?
CD4+ (helper) T cells
What type of APCs are found throughout the body in the skin, spleen, liver, thymus, and lymph nodes?
What receptors on dendritic cells recognize pathogen-associated molecular patterns?
toll-like receptors (TLRs)
What receptors on T lymphocytes recognize antigens bound to MHC I or MHC II on APCs?
T-cell receptor (TCR) complex
Which cluster of differentiation functions as a co-receptor for the TCR complex?
Which clusters of differentiation stabilize the interaction of the TCR with the MHC molecules?
CD4 and CD8
What is the term for signals outside of the TCR which are required for activation of the T cell during antigen presentation?
What is the consequence of the absence of co-stimulatory signals during T cell activation?
anergy or apoptosis
What receptor on cells bind to CD40 on Β cells that are presenting antigen?
What lymphokine receptor binds IL-2 secreted by activated helper T cells and stimulates T-cell growth?
interleukin-2 receptor (IL-2R)
What are the five steps of antigen presentation by MCH I molecules?
- ubiquitin targets antigens to the proteasome, where they are digested proteolytically
- transporter associated with antigen processing (TAP) transports the peptide fragments to the endoplasmic reticulum (ER)
- in the lumen of the ER, the protein tapasin links TAP with an MHC I
- aminopeptidase cleaves the peptide to fit the peptide-binding cleft MHC I
- the MHC l-peptide complex is transported to the Golgi apparatus, then exocytosed
What cells recognize the MHC l-peptide complex?
CD8+ cytotoxic T lymphocytes
Which macrophage receptors recognize the constant region of antibodies?
Which macrophage receptors recognize the complement component that binds to pathogens?
What proteolytic enzymes digest internalized antigens in late endosomes or lysosomes?
What are the five steps of antigen presentation by MCH II molecules?
- MHC II in the ER is transported to lysosomes containing antigens by invariant chain (Ii), which blocks the MCH II peptide-binding cleft
- in the lysosomes, Ii is degraded into class II-associated invariant chain peptide (CLIP)
- CLIP is removed by the action of another MHC molecule called HLA-DM
- exogenous peptides bind to MHC II and are trimmed by proteases
- the MHC lI-peptide complex is transported to the cell surface
What cells recognize the MHC Il-peptide complex?
CD4+ helper T lymphocytes
What is the T cell activated to produce after it binds to he MHC II-peptide complex (for CD4 cells) or the MHC l-peptide complex (for CD8 cells)?
IL-2 and IL-2R
What are the seven steps of CD4 T cell activation after it binds to MHC II-peptide complex?
- Lck phosphorylates tyrosine-based activating motifs (ITAMs) on the ζ-chains of the TCR
- ZAP-70 binds to the phosphorylated ITAMS and is is phosphorylated by Lck
- ZAP-70 phosphorylates linker of activated T cells (LAT)
- LAT cleaves inositol bisphosphonate into DAG and inositol triphosphate (IP3)
- DAG activates PKC, which phosphorylates ΙκΒ, which enables NF-κΒ to enter the nucleus
- IP3 induces release of Ca2+, which activates calmodulin, which enables NFAT to enter the nucleus.
- NFAT and NF-κΒ transcriptionally activate several genes to express IL-2
What are the three main types of helper T(Th) cells that CD4+ T cells can differentiate into?
What is the is the interface between an antigen-presenting cell or target cell and a lymphocyte called?
What is the precursor Th cell called after is it initially activated by the immunological synapse?
Which cytokine secreted by APCs stimulate the Th0 cell to differentiated into Th1 cells?
What three cytokines are secreted by Th1 cells?
Which cytokine secreted by follicular Th cells stimulate the Th0 cell to differentiated into Th2 cells?
What three cytokines are secreted by Th2 cells?
Which three cytokines secreted by dendritic cells stimulate the Th0 cell to differentiated into Th17 cells?
What anti-inflammatory cytokine is thought to suppress the production of Th1 and Th2 cells, thus stimulating the development of Th17 cells?
What three cytokines are secreted by Th17 cells?
What class of self-reactive CD4+ T cells block the potential activation of other T cells against self-tissues?
regulatory T (Treg) cells
What two cytokines are secreted by Treg cells?
What do cytokines cytokines secreted by Th cells, such as IL-2, induce CD8+ cells to differentiation into?
cytotoxic T lymphocytes (CTLs)
What two types of cytoplasmic granules CTLs function to induce apoptosis of infected cells?
What anionic phospholipid on the outer leaflet of the cell membrane induces phagocytosis of apoptotic cells?
What cell membrane receptor plays an important role in apoptosis by binding to ligands on the C TL?