Term
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Definition
| A small molecule that reacts with a specific antibody but cannot induce the formation of antibodies unless bound to a carrier protein or other large antigenic molecule. |
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Term
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Definition
| An adjuvant is an agent that may stimulate the immune system and increase the response to a vaccine, without having any specific antigenic effect in itself. |
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Term
| What cells are involved in eradicating the virally infected cells? |
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Definition
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Term
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Definition
KIT (SCF) Development
IL-4 (memory) 7 (development) 10 (plasma) Receptors
VLA-4 (VCAM-1 Development)
ICAM-1 (LFA-1 for Tcell signaling)
CCR7 (CCL21 from HEV to LN)
BAFF Receptor (Bcell activating factor)
CD40R (T-cells)
CD40L (Dendritic) |
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Term
| B-cell Receptor and co-receptor |
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Definition
| Ig, Ig alpha, Ig beta, CD19, CR2, CD81 |
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Term
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Definition
CD4 (Th)
CD8 (Tc)
CD2, 5 and 44 (Attachment and signaling)
IL-7R and Notch-1 Receptor (Signaling Thymocyte --> T-cell) |
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Term
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Definition
TCR ( Alpha/beta or gamma/delta)
2 zeta chains
2 CD3 Receptors (delta, gamma and 2 epsilon)
CD4 and 8 |
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Term
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Definition
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Term
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Definition
Tcells: CD28 --> B7 (CD80)increases proliferation and CTLA --> B7 decreases
B-cells:CD40L (Dendritic) CD40R (Tcell)
*this second signal is not required for Tc Cells! |
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Term
| Antibody Dependent Cell Mediated Cytotocxicity (ADCC) |
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Definition
ADCC is mediated by the NK cells
When NK cell (loaded with pre-formed cytotoxic granules) encounters the target cell coated with Abs its FcRs interact with Fc portions of the Abs
Cross-linking of the FcgammeRs leads to release of the toxins that kill the target cell |
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Term
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Definition
| Cellular Funtion - macrophage activation |
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Term
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Definition
| Humoral Fuction - antibody production, need for ADCC |
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Term
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Definition
An MHC Class I molecule is composed of one membrane-bound heavy alpha chain and noncovalently bonded beta2 microglobulin
The heavy chain has three extracellular (alpha1, alpha2 & alpha3) domains
1 & 2 domains form the peptide (Ag-derived) binding site |
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Term
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Definition
An MHC Class II molecule is composed of two membrane-bound chains: a chain and b chain. Each of them have two extracellular domains
a1 & b1 domains form the binding site fro the Ag-derived peptide |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
| Alternative C3 Convertase |
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Definition
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Term
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Definition
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Term
| Ab predominate in the blood |
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Definition
| IgM, IgG, and monomeric IgA |
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Term
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Definition
| IgG transported by FcR of mother |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| The ability of an antigen to elicit immune responses is called immunogenicity, which can be humoral and/or cell-mediated immune responses. |
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Term
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Definition
Some self-reactive T cells leak the negative selection mechanisms in the thymus & enter peripheral circulation
However, they are not going to be activated because when APCs present self-Ags, they do not express co-stimulatory molecules
Without 2nd signal T cell instead of activation becomes anergic (not responding to Ag) |
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Term
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Definition
IL-2 is secreted by T cells during their activation & is a major cytokine of the adaptive immunity
Secreted IL-2 is a ligand of IL-2R of the T cells, promoting their proliferation & differentiation
Both signals (through MHC/Ag & TCR and CD28 & B7) are required for expression of IL-2 gene |
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Term
| Is costimulation necessary for effector functions? |
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Definition
| Effector cells recognize Ag on the target cells & mediate their function without requirement for 2nd signal |
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Term
| Outcomes of opsinization through antibody |
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Definition
The opsonization thus promotes phagocytosis of pathogens
Alternative role of opsonization is in the classical pathway of complement activation because Abs bound to the surface of the pathogen cause complement fixation |
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Term
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Definition
| Induce local & systemic inflammatory reactions |
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Term
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Definition
Lymphocytes’
activation,
Production of IL-6 |
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Term
| Innate Immunity - viral infections |
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Definition
Extracellular phase
Complement system
Virolysis
Neutralization (Abs-mediated)
Intracellular phase
Type I interferon
Activation of the NK cells
Increases expression of ligands on the infected cells specific to the receptors on the NK cells
Natural killer cells
Destroy the virally infected cells |
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Term
| Innate Immunity - Bacterial Infectin |
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Definition
Macrophages are the first responders:
Phagocytosis
Synthesis of cytokines
Stimulating the liver
Chemokines promoting chemotaxis of neutrophils to the center of infection
Growth Factors for bone marrow
Liver
Acute-phase proteins
Complement system
Tagging the pathogen for phagocytosis
Lysing the pathogen
Bone marrow
More macrophages and neutrophils |
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Term
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Definition
All reactions are Ag non-specific (just against any molecular structures foreign to the human body)
Remaining major features of the innate immunity are:
No increase in response with repeated exposure to a given pathogen (no memory cells)
It is nonclonal defense mechanism |
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Term
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Definition
MHC Class I molecules are assembled in the ER, where they make complexes with antigenic peptides derived from the cytosol
The CD8 receptors bind to MHC I molecules to insure that Tc cells recognize a cytosol-derived Ag |
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Term
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Definition
MHC Class II molecules are also assembled in the ER (as MHC Class I) but they make complexes with antigenic polypeptides derived from the endocytic vesicles
The CD4 receptors bind to MHC II molecules to insure that TH cells recognize a endocytic vesicles-derived Ag |
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Term
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Definition
regulate migration (trafficking) of cells (chemotaxis)
Combined with cell-adhesion molecules, the chemokines facilitate the extravasation of leukocytes and homing in the tissues in areas of the immune reaction |
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Term
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Definition
Interferons were originally so named because they interfere with viral replication
There are two types of the Interferons:
Type I (IFN-α & IFN-β), Type II (IFN-gamma)
Mechanisms of action:
Activation of natural killer (NK) cells
Upregulation of the expression of MHC class I molecules (thus increasing the recognition and killing of virus-infected cells) |
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Term
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Definition
| can be produced by ANY infected cell |
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Term
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Definition
| secreted by TH, TC & NK cells |
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Term
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Definition
The transforming growth factor beta
The overall function of TGF-β is to down-regulate the inflammatory response, it is a negative feedback mechanism ‘switching off’ the inflammation-related reactions of the immune system when they are no longer needed
Mechanism of action:
It suppresses proliferation & differentiation of the immunocompetent & somatic cells
It is involved in regulation of cells apoptosis
Inhibit activation of macrophages |
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Term
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Definition
Interleukins (IL-3; IL-5; IL-7)
erythropoietin (EPO)
Granulocyte CSF (G-CSF)
macrophage CSF (M-CSF)
Granulocyte-macrophage CSF (GM-CSF) |
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Term
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Definition
CSFs are produced in the bone marrow in response to inflammatory cytokine IL-1
They promote maturation of the corresponding lineages of hemopoietic cells |
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Term
| Interleukin 12 Innate immunity |
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Definition
Innate Immunity:
Stimulates production of tumor necrosis factor-alpha (TNF-α)
Mediates enhancement of the cytotoxic activity of NK cells |
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Term
| Interleukin 12 Adaptive immunity |
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Definition
Adaptive immunity:
It stimulates the production of interferon-gamma (IFN-γ)
Mediates enhancement of the cytotoxic activity of CD8+ TC cells
A T cell stimulating factor and growth factor
It promotes differentiation of naive T cells into Th1 cells |
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Term
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Definition
IL-1 is secreted by monocytes & macrophages, fibroblasts, Dendritic cells and upon activation by many other types of blood cells
Its functions:
An endogenous pyrogen (induces fever)
Induces accumulation of leukocytes to the center of inflammation by regulating chemotaxis:
Promotes the expression of cell-adhesion molecules & chemokines
Activates vascular endothelium
Plays a role in regulation of the hematopoiesis
Induces secretion of IL-6 |
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Term
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Definition
IL-6 is produced by both lymphoid and nonlymphoid cells (T & B cells, monocytes and macrophages, fibroblasts, hepatocytes, keratinocytes, astrocytes, endothelial cells, and various tumor cells)
Secretion of IL-6 is primarily triggered by IL-1
IL-6 is a pleiotropic cytokine, affecting:
Production of the acute phase proteins by liver
Activation of B cells
Promotes B cells differentiation into plasma cells & immunoglobulins (Ab) synthesis
Activation of T cells
Promotes production of cytokines by CD4+ cells |
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Term
| Tumor Necrosis Factor (TNF-α) |
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Definition
TNF-α is secreted by monocytes, macrophages, neutrophils, NK cells and CD4+ T cells and some tumor cells
TNF-α is the major member of the TNF superfamily
The main trigger for its production are lipopolysaccharides in gram-negative bacteria
TNF-α exists in both membrane-bound and soluble forms
TNF-α functions:
Causes vasodilation and increased vasopermeability
Induces secretion of the cell-adhesion molecules & chemokines
Promotes expression of MHC class II molecules
Anti-tumor immunity |
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Term
| The major cytokines involved in triggering innate immunity reactions are: |
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Definition
Interleukin-1 (IL-1)
Tumor necrosis factor-α (TNF-α)
Interleukin-6 (IL-6) |
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Definition
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Term
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Definition
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Term
| Major cytokines mediating Treg cells function are |
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Definition
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Term
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Definition
| There are several genes encoding MHC proteins with different Ag-binding specificities |
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Term
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Definition
| There are multiple alleles of each gene |
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Term
| The diversity of MHC molecules is due to |
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Definition
Existence of the gene families, consisting of multiple genes encoding different chains of MHC molecules
Genetic polymorphism, which is presence of multiple alternative forms (alleles) of a gene |
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Term
| Neutrophils’ Extravasation 4 steps |
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Definition
Step I: rolling of neutrophils along the blood vessel wall is slowing down
Step II: neutrophils hold to endothelial cells and stop rolling
Step III: diapedesis (neutrophil squeezes between neighboring endothelial cells & leave the blood vessel)
Step IV: movement into the center of the infection |
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Term
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Definition
type-II transmembrane protein that belongs to the tumor necrosis factor (TNF) family
Its binding with its corresponding receptor induces apoptosis |
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Term
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Definition
| FasR forms the Death-Inducing Signaling Complex (DISC) upon binding with FasL |
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Term
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Definition
Pathogen-Associated Molecular Patterns
highly conserved among microorganisms, BUT NOT expressed by human tissues
Molecular structure recognized by the innate immune system
A typical PAMP is bacterial DNA |
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Term
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Definition
| PAMPs are recognized by specific Pattern Recognition Receptors (PRRs) |
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Term
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Definition
opsonins that bind to microbial walls to tag them for degradation by the complement system or by phagocytosis
Mannose-binding lectin (MBL) is secreted by liver as one of acute-phase proteins. It recognizes carbohydrates on bacteria, yeast & some parasites |
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Term
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Definition
are expressed on the surface of phagocytes and mediate the uptake & transport of the pathogen to lysosomes
Mannose receptors
Scavenger receptors
NOD1 & NOD2 (proteins with nucleotide-binding domain) |
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Term
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Definition
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Term
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Definition
expressed on monocytes, macrophages & dendritic cells
alpha and gamma chains, gamma chain mediates function
FcRI can bind to IgG in the absence of Ag *
Once IgG traps an Ag on the surface of monocytes, macrophages & dendritic cells it leads to its uptake and destruction |
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Term
| high affinity membrane receptors for Fc portion of IgE |
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Definition
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Term
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Definition
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Term
| In the follicular centers |
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Definition
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Term
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Definition
T cell area
T cells already differentiated in the thymus |
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Term
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Definition
antigen presentation
iDC recognize specific chemical signatures on the pathogens through pattern recognition receptors (PRRs) such as the toll-like receptors (TLR)
In the process of phagocytizing and degrading the proteins of the pathogens and migrating to the lymph nodes they become mature Ag-presenting DCs (mDC)
Upon maturation DCs acquire CD80, CD86 and CD40 receptors (co-stimulatory molecules) important for their function in T Cell activation.
Link between adaptive and innate immunity |
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Term
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Definition
WBC, granulocyte, which granules are susceptible to staining by base dyes
Express receptors for IgE, IgG, complement & histamine (role in allergic reactions)
Granules of the basophils contain:
Heparin & Peroxidase
Prostaglandins & Leukotrienes (factors of anaphylaxis)
Platelet activating factor
IL-4, cytokine that stimulates the proliferation of activated B-cells
IL-5, the growth factor for eosinophils |
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Term
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Definition
are residents of the connective tissue of bone marrow origin
They secrete:
Histamine
Leukotrienes
Different enzymes |
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Term
| First class of ab made in immune response |
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Definition
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Term
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Definition
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Term
| Which IgG does not cross placenta easily? |
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Definition
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Term
| IgG not a complment activator |
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Definition
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Term
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Definition
| digests into 3 segments 2 Fab and one Fc |
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Term
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Definition
| digests into 2 segments F(ab)2 and Fc |
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Term
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Definition
| 2 H chains and 2 L chains |
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Term
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Definition
process of constructing an exon which includes a single version of all variable constituents of each segment (VL & JL for light chain & VH, JH & D for heavy chain) to be transcribed into mRNA
This is the first factor contributing to the ultimate diversity of Abs. |
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Term
| recombination signal sequences (RSSs) |
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Definition
| The recombination of V, J & D regions of gene segments is directed by recombination signal sequences (RSSs) |
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Term
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Definition
| The set of enzymes that combine V, D & J segments is called V(D)J recombinase & is encoded by recombination-activation genes (RAG-1 & RAG-2) |
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Term
| Steps in Somatic Recombination |
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Definition
Step 1: RAG-1 binds to one type of RSS & RAG-2 to another
Step 2: Interaction between two RAGs
Step 3: Detachment of the formed loop
Step 4: Removal of nonfunctional ‘signal joint’
Step 5: Formation of coding joint |
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Term
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Definition
The second factor contributing to diversity of the Abs hypervariable regions
addition of nucleotides (that were not encoded in the germline DNA) by the enzymes involved in formation of the coding joint
The added nucleotides are:
P nucleotides
N nucleotides |
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Term
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Definition
| Alternative splicing is a process by which the exons of the RNA produced by transcription of a gene (pre-mRNA) are reconnected in multiple ways during RNA splicing. The resulting different mRNAs are translated into different protein isoforms. |
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Term
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Definition
After maturation in the bone marrow B cells are released into peripheral blood circulation & before encounter with an Ag
Only IgM & IgD
Both these isotypes can be expressed simultaneously on the same cell (an unique feature, characteristic only for naïve B cells) |
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Term
| Combinatorial Association |
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Definition
(third*) contribution to the overall diversity of Ig molecules
the association of heavy & light chains, the combinatorial (in different combinations, either , or light chains & either one of 9 heavy chains isotypes with the same Ag specificity) association |
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Term
| naive B cells encounter ag |
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Definition
triggers their proliferation (clonal expansion in the secondary lymphoid tissues, mainly in the lymph nodes) & differentiation
Ultimately these processes lead to evolvement of Plasma cells and production of Abs
As the immune response progresses, Abs with different properties are made as a result of:
Somatic hypermutation
Isotype switching |
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Term
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Definition
| The point mutations (single-nucleotide substitutions) are randomly introduced at a high rate throughout the rearranged V regions (only!) of heavy chain & light chain genes |
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Term
| Somatic hypermutation is dependent on the enzyme |
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Definition
| activation-induced cytidine deaminase (AID) |
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Term
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Definition
After somatic hyper mutation
As the adaptive immune response proceeds, Abs of progressively higher affinity are produced |
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Term
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Definition
Isotype switching occurs only in B cells primed with Ag (proliferating in the response to antigenic stimulus) and, as somatic hypermutation, is dependent on AID enzyme (activation-induced cytidine deaminase)
Occurs by somatic hypermutation |
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Term
| B cell development stages |
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Definition
| Precursors in BM > - selection> + selection > blood/lymph circulation > priming > activation > Proliferation and differentiation |
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Term
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Definition
| HSC > Lymphoid cell > Pro B > Pre B > Immature > Mature > Activated > IgM secreting > class switching >Memory and Plasma cells |
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Term
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Definition
Difference is in the lack of Ig light chain, which is replaced by the surrogate light chain made up from the VpreB & 5 polypeptides
Pre-B cell receptor is not expressed on the cell membrane, it remains in the cell’s cytoplasm |
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Term
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Definition
| In a developing B cell, the process of Ig gene rearrangement is tightly controlled that only one heavy chain & one light chain of the same specificity are expressed |
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Term
| Pre B cell receptor role in allelic exclusion |
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Definition
Once rearrangement of the first immunoglobulin locus is successful, the synthesis of chain & assembly of the pre-B cell receptor signals:
To stop transcription of RAG genes
To degrade the existing RAG proteins
To stop further somatic rearrangement in the M heavy chain locus |
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Term
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Definition
| the strength of the reaction between a single antigenic determinant and a single combining site on the antibody |
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Term
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Definition
a measure of the overall strength of binding of an antigen (by its multiple epitopes) with multivalent antibodies
It is influenced by both the valence of the antibody and the valence of the antigen and is more than the sum of the individual affinities |
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Term
| Stromal Cells of the Bone Marrow |
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Definition
| provide special microenvironment for B cells maturation. They make direct contact with developing B cells & produce specific growth factors, such as Stem Cell Factor (SCF), IL-7 and some others |
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Term
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Definition
| IL-6, IL-15, 8D6 & BAFF, which induce transformation of B cells into large centroblasts |
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Term
| Thymus-Independent (TI-2) Ags |
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Definition
| TI-2 Ags are composed of repetitive epitopes expressed on the surface of microorganism at so high density that they cross-link B cell receptors & co-receptors so extensively that there is no need for additional signals |
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