Cell Mediated Immunity and Humoral Responses I Flashcards
Anergic cell
A cell that no longer responds, can happen to B cells or T cells, is a result of receiving signal 1 w/o signal 2
What is the term for the category that CD4 and CD8 are in?
Co-receptors
What molecule interacts with B7-1 (CD80) and B7-2 (CD86)?
CD28
What is the term for the category that LFA-1 and ICAM-1 are in?
Adhesion molecules
What is the term for the category that NFkB, NFAT, and AP-1 are in?
Transcription factors
What is the term for the category that anti-TCR, Phytohemagglutinin (PHA) and lipopolysaccharide (LPS) are in?
Polyclonal activators
Humoral immunity implies the production of what?
Antibodies
What type of cell always expresses B7-1 or B7-2?
Antigen presenting cells
Interaction of what two molecules initiates signal 2 in T-cells?
CD28 with either B7-1 or B7-2
Signal 1 and Signal 2
Signal 1 - antigenic signal, created by TCR or BCR, Signal 2 - transduction signal, created by co-stimulators
What is required for B/T cell activation?
Antigen, co-stimulation, and cytokines
ITAM
Immuno-receptor tyrosine-based activation motif
What brings antigen to secondary lymphoid organs so T cells can see it?
Dendritic cells or monocytes
Alloantigens
Non-self MHCs that can be recognized by T-cells at high rates (1-3 percent of T-cells responding)
What percentage of T-cells get activated by alloantigens, superantigens, and polyclonal activators respectively?
Alloantigens - 1 to 3 percent, Superantigens - up to 20 percent, Polyclonal activators - 10 to 100 percent
Where are T-cell and B-cell rich zones respectively located?
T-cell rich - paracortical areas of lymph nodes and periarteriolar lymphoid sheath of spleen, B-cell rich - follicles of lymph nodes and spleen
What are the co-receptors on T-cells and what do they do?
CD8 and CD4, they help stabilize the interaction of presented antigen
In non-immune individuals, what is the frequency of T cells specific for a typical antigen?
Between 1 in 10 to the 5th and 1 in 10 to the 6th
What is used for co-stimulation with B-cells?
CD40L (on a helper T-cell) binding to CD40 (on the B-cell)
Are costimulators constitutively or transiently present on the surface of cells that provide costimulation?
Transiently (this helps prevent non-specific co-stimulation)
What is the less commonly used co-stimulatory receptor on B-cells and what does it bind?
CD21 (CR2), it binds a C3d (which is cleaved from C3b) - coated microbes
Follicular B cells
Live in follices of secondary lymphoid organs, require helper T-cell co-stimulation for activation
T-independent antigens, define give an example and identify what type of molecule can be a t-independent antigen
Antigens that can activate a B response without T-cell help, generally large molecules with repeating identical subunits, e.g. bacterial polysaccharides, glycolipids and nucleic acids
What types of B cells respond to T-independent antigens and where is each type found?
Marginal zone B cells (spleen) and B-1 B cells (peritoneal cavity and mucosal tissues)
What type of B response occurs in the case of T-independent antigens
An IgM response, with little or no isotype switching
Is a T-independent B-cell response considered high memory or low memory?
Low memory (memory and isotype switching require signals from T-cells)
What type of cell uses ITAMs and where do they fall in the process of cell activation?
T-cells. After antigen recognition and signal 1 and 2 are activated, Src Family TKs (such as Lck) phosphorylate ITAMs which then activates two pathways to gene transcription
In T-cell and B-cell activation, what are the two major downstream pathways that lead to gene transcription?
The Calcium-NFAT pathway (PLC, IP3, DAG) and the Ras/Rac-MAP kinase pathway
What are the three main transcription factors activated in B and T cell activation?
NFAT, NF-KB, and AP-1
B-cell activation requires clustering of what and what is the result of this clustering?
2 or more antigen receptors cluster and then tyrosines in the ITAMs of Ig-alpha and Ig-beta are phosphorylated
Give the proportion of B cells specific for a given antigen in the case of unimmunized individual, peak response individual, and post response (memory) individual
Unimmunized - 1 in 10 to the 5th or 6th, Peak response - 1 in 10 cells, Post response - 1 in 100 or 1000 cells
