Cells of the lymphoid system Flashcards
Which proteins do all T cells express?
CD2
CD3
CD28
CTLA4
PD1
What are the 4 main classes of Th cells?
Th1
Th2
Tfh
Th17
What two cytokines to Th1 cells produce?
IFNg
IL-2
What is the role of Th1 cells?
Destroy intracellular pathogens
Role of IFNg
Activates macrophages and help them become more adept at destroying intracellular pathogens
Released upon recognising non-native antigens presented on APCs
Role of IL-2
Interaction of Th1 and APCs through CD40 and CD40L stimulates APCs to produce IL-12
IL-12 and IL-2 help proliferation of CD8+ T cells and NK cells
Which cytokines do Th2 cells release?
IL-3 IL-4 IL-5 IL-9 IL-13
What do Th2 cells protect against?
Allergies
Parasitic infections
Role of cytokines secreted by Th2 cellls
Activation of granulocytes and mast cells
Promote class switching to IgE
Cytokine expressed by Tfh cells
IL-21
Role of Tfh cells
Express CD40L to interact with CD40 on B cells
Do not present antigen
Rather promote proliferation, class switching and affinity maturation in B cell follicles
Cytokines expressed by Th17 cells
IL-17
IL-22
What do Th17 cells protect against?
Extracellular pathogens and fungi
Role of Th17 cells
Promotes neutrophil recruitment and tissue inflammation
Often present in mucosal surfaces
IL-17 stimulates other non-immune cells to produce chemokines leading to neutrophil recruitment and inflammation
Markers of Tregs
CD25
FoxP3
Two main cytokines released by Tregs
IL-10
TGFb
What is the role of IL-10 secreted by Tregs?
Stimulates B cell proliferation
Anti-inflammatory by suppressing Th1 cells
What important receptor do Tregs express?
CTLA-4
Modifies APCs through blockign or removing B7
What is the marker of Cytotoxic T cells?
CD8
4 ways in which CTLs carry out their function
Interact with MHC class I
Kill infected cells
Produce IFN
Activates surrounding macrophages through releasing cytokines
What two ways do CTLs kill infected cells?
Death-receptor-dependent killing - interact with Fas on target to induce apoptosis
Granule-dependent killing - perforin produces pores on the membrane which allows the insertion of granzymes
Role of IFN
Attempt to inhibit viral invasion of host cells through
- inducing an antiviral state
- inducing intracellular killing
Which proteins do B cells express?
CD19
CD80/86
Which proteins do NK cells express?
CD16
CD56
What is the difference between the ways NK cells eliminate pathogens, and the way CTLs eliminate
pathogens?
Instead of looking for the foreign antigens, they look at the MHC itself
Cells missing MHC evade immune responses
