Producer - macrophage, endothelial cell, epithelial cell

Actions - Inflammation, fever (via prostaglandins), incr. acute phase proteins liver, increase Th1 cells

IL-2

(producer cell, actions)

Producer cells - TH0, TH1, TC cells.

Actions - lymphocyte proliferation (T,B, NK) and NK--> cytotoxcity

IL-3 multicolony CSF

Producer, Actions

Producer cells - CD4+ T cells, thymic epithelial cells;

Actions - synergestic action in early hematopoesis;

IL-4

producer, actions

producer cells - TH2, mast cells

actions - B cell activation, IgE and IgG4 switch, decr. TH1 cells/macrophages, decr. IFN-gamma, decr. DC-IL-12, incr. mast cells, TH0-->TH2;

IL-5

producer cell, actions

producer cells: TH2 cells, mast cells;

actions: incr. IgA (post switch), incr. eosinophil growth and differentiation, incr. CD25 on mem. B cells, incr. growth of activated B cells;

IL-6

producer cells, actions

producer cells - T cells, macrophages, endothelial cells.

actions - incrs. T and B cell growth/differentiation, incr. plasma cell growth, acute phase protein production, fever;

IL-10

producer cells, actions;

producer cells - many cells, T reg cells

actions - incrs. MHC II Class for B cells, decrs. TH1, decrs. cytokine secretion, co-stimulates mast cells, immunosuppressive, suppresses activation of macrophages;

IL-12

producer cells, actions

producer cells - DCs, macrophages;

actions - incr. NK cells, TH0-->TH1;

IL-13

producer cells, actions

producer cell - TH2 cells

actions - B-cell growth/differentiation, decrs. macrophage inflammatory cytokine prudction, and decrs. TH1 cells and IgE switch;

IL-17

producer cells, actions

producer cell - TH17

actions - IL-2 like, incrs. growth of intestinal epithelium, T cells and NK cells, pre Tc --> Tc inflammation by recruiting immune cells to infected tissue, IgG3 switching, involved in TH 17 differentiation;

IG-23

producer cells, actions

producer cells - DCs

actions - IL-2 like, incr. growth of ints. epithelium, T cells and NK cells, pre Tc --> Tc inflammation by recruiting immune cells to infected tissue, IgG3 switching, involved in TH17 differentiation;

TGF B

producer cell, actions

producer cell - CD4 T cells;

actions - IgA switch factor, incr. B cell growth, incr. macrophage activation, incr. neutrophils, decr. T cell activation, incr. fibrosis and wound healing, incr. phagocytic activity;

TNF alpha (cachectin)

producer cells, actions

producer cells - macrophages, NK cells, T cells;

actions - local inflammation, fever (toxic shock at high concentration), incr. endothelial cells;

TNF-beta (lymphotoxin, LT)

producer cells, actions;

producer cells - T cells, B cells;

actions - Killing, incr. endothelial cells;

IFN - gamma

producer cells, actions

producer cells - TH1 cells, NK cells, CD 8 cells, T reg cells;

actions - macrophage activation,  incr. expression of MHC and FcRs on B cells, incr. IgG1 class switching (post switch), decr. IL-4 and TH2 secretion factor for Human IgG1;

limit viral infections induce fever inflammation, and antibody production;

IFN alpha/Beta = type I

IFN gamma = type II

1. lipids and lipopeptides

2. proteins

3. Nucleic acids

4. self ligands including HSP, Fibrinogen, hyaluronan, fibronectin;

Toll like receptors (TLR)

Downstream effects

1. recruitment of adaptor proteins

2. activation of signal transduction molecules

3. activation of MAP Kinases

4. nuclear translocation of NF-kappaB

L Selectin (CD62L)

Vascular Addressins and Homing specif.

vascular addr. on EC of blood vessels: CD34, glyCAM-1;

Homing specificity:virgin lymphocytes to lymph nodes;

L Selectin (CD62L)

vascular addressin: MAdCAM

Specificity?

alpha4/beta7 integrin

vascular addressins: MAdCAM VCAM-1

homing specificity?

virgin lymphocytes to peyers patches;

memory effector cells to lamina propria of GI tract;

cutaneous lymphocyte antigen (CLA)

vascular addressins: E-Selectin P-Selectin

homing specificity?

VLA-4/LFA-1

vascular addressins: VCAM-1/ICAM-1(CD54)

homing specificity?

Bence Jones Proteins

def.

Enzymatic cleavage of IgG

Papain

Pepsin

Papain: cleaves molecule N terminal to the disulfide bonds in the hinge = 2 Fab and 1 Fc segmen.

Pepsin: cleaves the molecule C terminal to the disulfide bonds in the hinge region generating an F(ab')2 molecule and Fc fragments.

Ig type in Blood

Tissue Fluids

blood - IgG & IgM; low levels of IgA, IgD, IgE;

tissue fluids - IgG; trace IgM and IgA monomers;

Ig Type in Secretions

Fetus

Secretions - IgA dimers; small amt of IgG in tears, bronchi, esophagus, gut, breast milk;

Fetus - Passive IgG from mom (IgG1,3,4)

Ig type Beneath Epithelium

Brain

Beneath epithelium - IgE on mast cells

Brain - nowhere unless blood brain barrier is damaged.

long half life 3 wks (cept IgG3)

found in lymph and blood

secreted late primary early secondary

subtypes 1,4,3 cross to fetus

opsonizing antibody

mediates ADCC

neutralizes viruses and toxins

monomer on B cell surface (no hinge)

5 fxn binding sites (10 possible)

first Ig to appear during ontogeny

first Ig during an immune response (pentamer)

Natural isohemagglutinin (anti-AB)

second recptor on B cell (with M)

sensitive to proteolysis

rare but found in serum

binds basophils mast cells, and eosinophils;

no hinge

short half life

extra H domain

Allergy and anaphylaxis

protection against worms;

dimer in secretions

two subclasses

short half life

major Ig in body and external secretions

protects mucosal surfaces

Isotypes

def

allotypes

def.

allelic forms of the same protein which vary among members of the same species.

Changes in one or two AAs in constant region of heavy or light chain.

Idiotypes (Ids)

definition

variable region of the heavy and light chains of the antibody.

you can generate anti-Id antibodies against the variable regions of one homogeneous (clonal) immunoglobuilin that will not react with other immunoglobulin molecules and for the B cell that made it. Anti-IDs can go into the combining site or on the periphery of the combining site.

Components of TCR complex

TCR (does not extend into cytosol);

CD3 (gamma, delta, epsilon chains) that form 2 pairs that extend into the cytosol of the cell;

CD3 associates with TCR once it has bound its antigen;

zeta molecules exntend into the cytosol and bind the TCR

Kappa chain locus

lambda chain locus

kappa chain locus - chromosome 2 with VJ segments and single Ck segment;

lambda chain locus - chromosome 22 w/ VJ segments and 4 Clambda gene segments;

Antibody rearrangments

order

Ag independent only in B cells

H chain first

Lambda chains second (kappa before beta)

allelic exclusion

def.

each cell selects only one parental Vh and one parental Vl (kappa/lambda)

each B cell clone has one BCR (many copies of it)

TCR

chain combinations

alpha/beta - biclonal (two alphas) or monoclonal (alpha/beta)

gamma/delta - allelically excluded, always monoclonal;

prozone

postzone

def.

prozone - in excess of antibody weak or no precipitation may occur;

postzone - if antigen is in excess, weak or no precipitation may occur;

Direct Coombs Test

Used to detect the mother's anti-Rh IgG in the babys blood (acquired through the placenta);

agglutination of the newborn's RBC coated with the mother's anti-Rh AB by an anti-IgG Ab;

if agglutination occurs the child has hemolytic disease;

Indirect Coombs Test

used to detect the prescence of anti-Rh Ab in the serum of the mother;

Rh positive RBCs are treated with the mother's serum.  If it contains anti-Rh antibody these RBCs will be coated with the mother IgG anti-Rh Ab;

Complement Nomenclature

(exception)

When a protein is cleaved by a protease the smaller fragment is labeled 'a' and the larger one 'b' (Ex. C3 --> C3a &C3b)

exception: C2 --> C2a (bigger) & C2b (smaller)

Complement System

Overview Fxn.

Complement

Specific Fxns.

A. Generation of peptides with potent biological activities.

B. Formation of macromolecular complexes with enzymatic or membrane altering properties.

C. Covalent modification of other macromolecules.

Protective Effects of Complement

(4)

A. Lysis of bacteria

B. Causing inflammation (recruiting neutrophils, etc.)

C. Opsonization (marking for uptake by phagocytes)

D. Preventing immune complex damage (removal from circulation)

Classical Pathway

Recognition

CP Activators

(4)

IgM, IgG (3,1,2,4), Apoptotic Cells, Oxidized LDL;

Immunoglobulins are the most important activators.  C1q binds to the Fc portion of immunoglobulins.  One IgM molecule or two IgG molecules can activate C1q;  Only aggregated (bound) immunoglobulin not soluble can activate.

C1q + Ig activates the serine protease activity in C1s which cleaves C4 and C2 into two fragments each.

Cleaved C2 has protease activity and breaks C3 into two fragments.

C2+C4 = C3 Convertase + C3b = C5 Convertase

C3 and C4 have a posttranslational modification an internal thiolester bond, an unstable high energy intermediate.

After cleavage of C3 or C4 by proteases the thioester gets exposed and gets attached to nearby proteins or carbohydrates (cell surfaces, bacteria, viruses, and Igs.

Lectin Pathway Activators

(1)

Mannose containing microbial carbohydrates Agalactosyl IgG

Mannose binding lectin (MBL)

Attachment of C3 lectin Pathway

A. Lytic channels form once C5 converatase cleaves C5.  C5b binds to C6 and C7;

B. C8 binds and begins membrane perturbation;

C. C9 binds and then undergoes conformational change which allows it to selfpolymerize into a pore.

D. MAC disrupts cellular homeostasis, allowing ions, water, and bacteriocidal proteins (lysozyme) across the cellular membrane.

C1qR

ligand

sites of expression

biological effects

ligand - C1q bound to immune complexes;

sites of expression - leukocytes, endothelium, epithelium, platelets;

biological effects - phagocytosis (main), oxidative burst by PMN, ADCC, cytokine release;

CR1 (CD35)

Ligand, expression, biological effects

ligand - C3b, C4b;

expression - RBC, PMN, monocytes, B cells, FDC, Kupffer cells, glomerular podocytes;

Effect - removal of IC, phagocytosis, antigen presentation;

CR2 (CD21)

ligand, expression, biological effect

ligand - C3d,g;

expression - B cells, thymocytes, FDC;

Effects - B cell co activator, antigen presentation;

CR3 (CD 11b/CD18)

ligand, expression, biological activity;

ligand - C3Bi;

expression - PMN, monocytes;

biologic activity - phagocytosis;

CR4 (CD11c/CD18)

ligand, site of expression, biological function;

ligand - C2bi

expression - PMN, monocyte;

biological effect - phagocytosis;

Anaphylatoxins

small amino terminal fragments of C3, C4, and C5 generated during complement activation are potent inflammatory mediators;

The polypeptides responsible for anaphylactoid shock and death.

They bind to specific cell surface receptors.  They promote inflammation/recruitment of neutrophils, monocytes to tissue injury, and promote hemostatis and cytokine production;  Can also result in tissue damage or organ failure in widespread complement activation;

Regulation of C1s Activity

Main regulation at the level of C3/C5 convertases;

Factor I cleaves C3 into inactive fragments.

RCA proteins with Co-Factor activity - cleave C3/4 in presence of Factor I;

Factor H, C4bp, Membrane cofactor protein (MCP), CR1 (CD 35);

RCA proteins with Decay acceleration activity

disrupt the non covalent association of C3 with enzymatic components of the convertases (C2a/Bb)

Factor H, C4bp, Decay accelerating factor (DAF), CR1 (CD35);

Regulation of MAC

(3)

Vitronectin (S protein) - binds C5b-7 trimer and renders it hydrophilic, preventing membrane insertion;

Clusterin (SP-40) - prevents C5b-9 that forms in the serum from binding to cells;

CD59 - membrane protein on erythrocytes, leukocytes, and endothelial cells.  binds to C8 and prevents incorporation and polymerization of C9.

Prothymocyte V region

Rearrangement Order

gamma, delta, beta, alpha

TCR Positive Selection

Cortex of Thymus - If TCRs on a T cell recognize class I or class II with high affinity --> apoptosis.

If the TCR do not recognize Class I or II with any affinity --> die of neglect.

TCRs with low/medium affinity for Class I/II migrate to the medulla.

Negative Selection

Location of T cells in the periphery

(4)

a. cortex of lymph node

b. periarterial sheath of spleen

c. intranodal areas of peyer's patches (lower GI)

d. activated by heat shock proteins and mycobacteria;

Ligands for B7 costimulatory molecules

expressed on APC (2)

CD28

CD152 (CTLA-4)

Interacts with CD40 expressed on APC (1)

CD154(CD40L)

Adhesion Molecules on T Cell

(2)

CD11a/CD18(LFA-1)

CD49d/CD29 (VLA-4)

Homing molecule

Naive T Cell --> lymph Node via HEV

(1)

Alpha Chain of the IL-2 receptor on

activated T and B cells

(1)

Signals in T/APC immune response

(3)

signal 1 - recognize MHC/peptide via TCR

Signal 2 - engagement of costimulatory molecule w/ ligand

Signal 3 (pseudo)  - binding of integrin to integrin receptors strengthens the avidity of the rxn. 

anergy

(def)

CD4+ Regulatory T Cells

a)  Foxp3CD4+CD25+ T cells (T reg) --> develop in the thymus, require TCR engagement but once activated suppress (via cytokines) the proliferation and activation of CD4 and CD8 T cells;

b) Tr1 -develop in periphery produce IL-10

c) Th3 - develope in periphery involved in oral tolerance produce (TGF-B and IL10);

Biologic Fxns of Chemokines

(5)

1. leukocyte chemotaxis

2. integrin activation during leukocyte endothelial interactions

3. leukocyte degranulation and mediator release

4. angiogenesis/angiostasis

5. fibrosis and wound healing

Th1 cell

dev./fxn

Th0-->Th1 via antigen & IFNgamma;

involved in cell mediated immunity & defense against intracellular pathogens;

Produce:

IL-2 (B cell incr. Ab opson. of Bact. & act. Tc); IFN-gamma (mac. incr. kill & B cell Ab ops. of bacteria);

 TNF a/b (neutro microb. killing);

Th2 cell

dev. fxn. mol. produced

Th0-->Th2 via antigen, IL-4 (NK T cells);

Gen. of hum. immun., inhib inflam., Reg IgE against parasites;

Produce: IL-4,5,13;

Th1 & Th2

common cytokines produced

(5)

IL-3, GMCSF, IL-10, TGF-B, IL-6;

both can become memory cells;

Th17

dev./fxn./mol. prod.

Th0-->Th17 via TGF-B, IL-12, IL-6;

inflammatory resp. against extracellular pathogens;

Produce: IL-17;

Treg

dev./fxn./mol. prod.

Th0-->Th17 via TGF-B;

fxn. - immunosuppresion of T cell and macrophages;

produce immunosuppresive: IL-10 & TGF-B;

Dendritic Cell (DC)

cytokines produced

(5)

IL-12, TGF-B, IL-23, TNF-a, INF-a

NK Cell

cytokine (1)

IFN-gamma;

Macrophage

cytokines produced

(5)

IL-12, IL-1, TNF, IL-6, IL-8;

Mast Cell

cytokines produced (1)

IL-4;

NKT cell

cytokine produced

(1)

IL-4;

Immunosupprs. & tissue repair by Monocytes

Early - TGF-B & IL-10 (immunosuppresion)

Late - TGF-B, arginase (tissue repair)