Adaptive Immunity- Diebel Flashcards
What is an epitope?
Small part of an antigenic molecule, 10-20 amino acids
Region on antigen that can be recognizes by an antibody of by T-cell receptors (aka antigenic determinants)
How long does it take for the adaptive immune response activation?
7-10 days
Describe the different roles of T and B cells in the adaptive immune response?
B-cells protect the extracellular spaces - fluids blood secretions by releasing antibodies
T-cells- in charge of cell-mediated immunity (surveys the surface of body’s cells)
What is the difference between class I and class II antigens?
Class 1 = antigens synthesized within the cells (recognized by CD8+ Killer T-Cells)
Class 2 = antigens are products of phagocytosis (recognized by CD4+ Helper T-cells)`
What is CD3?
T- Cell Receptor!! (TCR)
What is the big difference between gamma-delta and alpha-beta T cells?
alpha beta must bind antigen+ MCH1 or MHC2
gamma-delta T-cells can function with out binding MHC and protect the mucosal surfaces of the body
The alpha-beta T-cell receptor will bind what on APCs?
Antigen
What does the CD4 or CD8 molecule on the T-cell bind to?
CD4= MHC 2 CD8 = MHC 1
What molecules act as a co-stimulatory signal for T-cell activation?
CD28 on the T-cell binds to CD80/86 on the APC
What molecular interactions act to strengthen the adhesion between a T-cell and APC during the process of T-cell activation?
ICAM-1 on APC binds LFA-1 on TC
LFA-3 on APC binds CD2 on TC
Role of Th1?
- makes lymphokine that attracts MACs
- INTENSE inflammation
Role of Th2?
stimulate MACs to become “alternatively activated”
helps to wall off pathogens
promote healing
usually takes place after Th1 response
important in parasite immunity
Role of Th17?
Focused inflammation
More powerful than Th1
Implicated in serious forms of autoimmunity
Role of Follicular Helper T-cells? Tfh
stimulated by antigen
migrate from t-cell areas of lymph nodes into the B-cell follicles
help get B-cells activated and make the antibody subclass
Role of T regs?
Make cytokines that suppress the activation and function of Th1, Th17, Th2
Role of cytotoxic or killer T-cells?
Destroy any body cell they identify as bearing a forgien or abnormal antigen on its surface
What cytokines are general activators/ proproliferative of T-cells?
IL-2
IL-15
What cytokines drive differentiation towards Th1?
IL-12 and IFN-gamma
What cytokines drive differentiation towards Th2?
IL-4
Where would you find MHC Class I molecules?
ALL CELLS! except for red blood cells
Describe function of Killer T Cells
Killer T cell recognizes abnormal antigen on MHC I molecule
expands and daughter cells circulate
once found the correct antigen, t-cell delivers lethal hit
Signals to cells to commit suicide through apoptosis
T-cells express FAS ligand, which binds to FAS on target cells and activates caspases
Also kills by releases cytotoxic agents (TNF, perforin, granzymes)
What different molecules do T and B cells secrete?
B lymphocytes secrete antibodies
T lymphocytes secrete short-range cell mediators = lymphokines (subset of cytokines)
Function of IgG
Two adajecent IgG bind antigen
cooperate to activate complement
What is the only antibody that can cross the placenta and protect a newborn?
IgG
Function of IgM
First to appear in blood after exposure to a new antigen
Located on B-cell surface (along with IgD)
It is replaced by IgG in a week or two after onset of infection
Polymeric
Better at activating complement than IgG
Function of IgD
main form of antibody inserted into B-cell membranes (as antigen receptor)
Function of IgA?
Most important class of antibody in the secretions like saliva, tears, genitourinary and intestinal fluids and milk
to be secreted must be combines with another chain= secretory component (gets from epithelial cells as its secreted)
Which antibody acts as the first-line of defense against pathogens trying to gain access through mucous membranes?
IgA!
Secretory component makes it resistant to digestive enzymes
Function of IgE?
Attaches to mast cells
When it enounters antigen, causes mast cells to make prostaglandins, leukotrienes, and cytokines and release powerful mediators of inflammation = HISTAMINE!
What antibody plays an important role in resistance to parasites, such as worms?
IgE!
Type 1 Hypersensitivity?
Patient make too much IgE to enviornmental antigen
Type 2 Hypersensitivity?
Antibodies react against self
Type 3 Hypersensitivity?
Occurs when someone makes antibody against a soluble antigen (antigen too small, get stuck in basement membrane and usual inflammatory response occurs)
Type 4 Hypersensitivity?
Cell-mediated hypersensitivity causes by activated CD4+ T-cells
Examples: contact hypersensitivity to nickel
TB reaction
Granulomatous hypersensitivty
X- linked agammaglobulienmia
Absence of B lymphocytes
CD40 ligand deficiency
Failure of immunoglobulin class switching
Activation-Induced Cytidine deaminase deficiency
Failure of immoglobulin class switching
Common Variable IMmunodeficiency
A failure to produce antibodies against particular antigens
Omenn Syndrome
VDJ recombination failure. Cannot produces T or B cell receptors
X-linked severed combined immunodeficiency
A failure to produce mature T-lymphocytes
DiGeroge syndrome
Failure of the thymus to develop correctly
Hemophagocytic lymphoistioyctosis
Failure of CD8+ T cells and NK cells to produce and/or release lytic granules
IPEX
A failure of peripheral tolerance due to defective regulatory T-cells
