Week 3 - Complement and Acute Phase + Serology Flashcards
What kind of globulins would show up high on Serum electrophoresis during:
Normal, Chronic Liver Failure, Chronic inflammation
Normal - Albumin
Chronic Liver Failure - Gamma would be relatively high since liver is not producing the others well enough.
Chronic Inflammation - Gamma would actually rise!
What is ESR? what does it tells us regarding Myeloma or Inflammatory Diseases?
Erythrocyte Sedimentation Rate: Diagnostic Tool
Negative Sialic Acid on RBC binds positive Igs and Fibrinogen, causing them to form a rouleaux faster!
What should we suspect if the Serum electrophoresis comes back with a peaked gamma globulin reading (not curved)? Example.
M-spike, it is an indication of a Monoclonal Gammopathy (Curved when Polyclonal).
One plasma cell colony is over-proliferating forming the monoclonal antibodies, e.g. Multiple Myeloma.
Agglutination Vs Precipitation
Agglutination - Corpuscular Antigen (like a RBC)
Precipitation - Soluble Antigen (like a Nutrient)
Antibody Titer
The Highest degree of dilution, where hemagglutination still occurs.
Indirect agglutination? use in lab?
Secondary Antibody binds first binding Antibody Fc region as an Antigen. used for Anti-D detection.
Passive agglutination? use in lab?
Haptens or Antigen bind pretreated RBCs/Latex.
Antibodies specific to coating molecules induce agglutination.used for Rheumatoid Factor Detection.
Indirect ELISA
1) Antigen binds pretreated vessel walls,
2) Serum antibody binds antigen
3) Treated Enzymatic Secondary Binds Fc portion of First
4) Enzyme produce colour even after wash (Bound)
Sandwich ELISA
1) Antibody Fc binds pretreated vessel walls,
2) Serum antibody binds antigen
3) Treated Enzymatic Secondary Binds Antigen +First complex
4) Enzyme produce colour even after wash (Bound)
Where are Complement proteins produced?
Liver Mostly and Immune cells
Upon cleavage of a Complement protein, one part will get an “a” name addition and other will get a “b”,
(C3-> C3a + C3b ) what do these mean?
a - Cleavage product diffuses away (anaphylatoxins)
b - Larger, Enzymatic Part stays in the site of cleavage
Parts of C1 ?
C1r , C1s , C1q
How does the Complement system aids Bacteria Killing?
1) Opsonins : C3b,Cbi,C3dg
2) Membrane attack complex (MAC) : C5b-C9
How does the Complement system links between the Innate and Adaptive Immune system?
- Antibody responsive
- by promoting opsonization it also promotes antigen presentation and cytokine release
How does the complement system helps in the elimination of Immune complexes?
(CR1 Function)
Erythrocytes membrane CR1s bind C3b-Antibody complexes to be phagocytosed by Splenic Macrophages later. (C3b/C4b receptor or CD35)
Immune Functions of CR2
CR2 (CD21) - B cell activation by C3dg (Late degredation Product) binding.
Complement Regulation proteins:
Inhibition of the classical pathway initiation:
C1 inhibitor: C1INA
Deficiencies in Complement:
Early Parts (C4,C2,MBL,C1 …)
C3 Convertase
Late Parts (C5b - C9)
Early parts - Autoimmune Diseases (SLE: Lupus )
C3 Convertase - Chronic Bacterial Infections
Late Parts (C5b - C9) - Chronic Neisseria Infections
Deficiencies in Complement Regulators
Deficiency in C1INH Causes:
C1INH Deficiency - Hereditary angioneurotic edema (Bradykinin elevated)
How does Acute phase reaction (APR ) differ from Inflammation?
APR develops later, it is systemic by default, onset is from above a threshold, Inhibits inflammation in order to restore Immune Homeostasis.
Time scale of progression of APR?
6-12 hr
What are the Second wave mediator of Inflammation that cause APR?
TNF
IL1
IL6
IL8
What are the acute phase reactions formed in (Second wave mediator targets): LIver Bone Marrow Adipose CNS
LIver - Acute Phase Proteins (like CRP)
Bone Marrow - Leukocytosis
Adipose - Lipid Mobilization
CNS - Hypothalamus: Fever
APR Events in Hypothalamus
APR Events in Hypothalamus:
- IL6 elevates CRH (parallelly ACTH and Cortisol) leads to inhibition of Inflammation.
- Fever by PGE2 formation
What are the Acute phase proteins formed in the liver:
- Serum amyloid A and P (SAA and SAP)
- C reactive Protein (CRP)
- Mannose binding Lectin (MBL)
- Fibrinogen (Promotion of Coagulation)
- Complement System Proteins
Name 3 proteins that decrease in concentration in production in liver in acute phase reaction:
- Transferrin
- Fibronectin
- Albumin
CRP:
PRR works as an Opsonin and Complement activator.
Main Acute phase protein.
Serum Amyloid-A (SAA):
Transfer cholesterol - Acute Phase HDL (Anti-Inflammatory)
Haptoglobin:
Macrophage Activation inhibitor and Iron Carrier
Coeruloplasmin:
Free radical scavenger and Copper Carrier
A2M (alpha2 - macroglobulin)
Protease Inhibitor (Anticoagulatory)
Why should we prefer measuring Acute phase proteins in blood over Cytokines level?
Cytokine level changes faster than acute phase proteins. Acute phase proteins always reflect the systemic condition.
What is the significance of measuring Acute phase proteins ?
Give an example for a test using these proteins:
Detection of Infection, Autoimmunity, Therapy monitoring, Hemolytic anemia.
we could have an ELISA for CRP or SAA proteins
Immune Functions of CR3 and CR4
CR3,CR4 - Integrin type receptors bind iC3b (Early Degradation product) and aid in phagocytosis. (Located on phagocytes)
What domain of the Antibodies is bound by the Complement factors?
CH2 Domain of the Antibody
What are the molecules possible to be binded for initiation of complement cascade? What part of the C1 is responsible for that?
Certain retroviral surfaces, LPS and Gram-negative bacterial surfaces, CRP.
These could be bound by C1q subdomain.
What are the two versions of C3 Convertase (Alternative and Classical) ?
- Classical: C4b2b
- Alternative: C3bBb
Complement Regulation proteins- Inhibition of C3 convertase:
C3 convertase Inhibition: I factor, DAF, MCP
Complement Regulation proteins-Inactivation of anaphylatoxins by cleavage of C3a and C5a:
Eliminate C3a/C5a:Serum Carboxypeptidase N (SCPN)
Complement Regulation proteins-Inhibition of MAC:
MAC Inhibition: Protectin (CD59)
What are the two versions of C5 Convertase (Alternative and Classical) ?
- Classical: C4b2b3b
- Alternative:C3bBbC3b
_____ Acid is a surface regulator for C3b.
Sialic Acid is a surface regulator for C3b.
Deficiencies in Complement Regulators - DAF deficiency causes:
DAF Deficiency - Paroxysmal nocturnal hemoglobinuria
Rationale of Measuring Acute Phase Proteins and Not Inflammatory Mediators?
Cytokine levels change faster but APPs reflect the general status better
Significance of Measuring Acute Phase Proteins ?
Detection of infection
Autoimmunity
Monitoring of therapy
Hemolytic anemia (haptoglobin)
Methods of Measuring Acute Phase Proteins ?
Erythrocyte sedimentation rate ->~ fibrinogen conc.!
Serum protein electrophoresis
ELISA - CRP/SAA
Classical Pathway:
1) C1 Binds Antibody (that is bound to the Bacteria mem.)
2) C1-Antibody complex cleaves C2 and C4
3) C2b and C4b bind membrane and form __ Convertase
4) __ is cleaved by convertase and ___ binds Mem.
5) C2bC4bC__ (5 convertase) Cleaves C5
6) C2bC4bC__C5b attracts C6 to 9 proteins
7) Membrane attack complex is formed
Classical Pathway:
1) C1 Binds Antibody (that is bound to the Bacteria mem.)
2) C1-Antibody complex cleaves C2 and C4
3) C2b and C4b bind membrane and form C3 Convertase
4) C3 is cleaved by convertase and C3b binds Mem.
5) C2bC4bC3b (5 convertase) Cleaves C5
6) C2bC4bC3bC5b attracts C6 to 9 proteins
7) Membrane attack complex is formed
Classical Pathway:
1) C1 Binds Antibody (that is bound to the Bacteria mem.)
2) C1-Antibody complex cleaves C2 and C4
3) C2b and C4b bind membrane and form C3 Convertase
4) C3 is cleaved by convertase and C3b binds Mem.
5) _____________ _________ ________ ___
6) C2bC4bC3bC5b attracts C6 to 9 proteins
7) Membrane attack complex is formed
Classical Pathway:
1) C1 Binds Antibody (that is bound to the Bacteria mem.)
2) C1-Antibody complex cleaves C2 and C4
3) C2b and C4b bind membrane and form C3 Convertase
4) C3 is cleaved by convertase and C3b binds Mem.
5) C2bC4bC3b (5 convertase) Cleaves C5
6) C2bC4bC3bC5b attracts C6 to 9 proteins
7) Membrane attack complex is formed
Classical Pathway:
1) C1 Binds Antibody (that is bound to the Bacteria mem.)
2) C1-Antibody complex cleaves C2 and C4
3) C2b and C4b bind membrane and form C3 Convertase
4) C3 is cleaved by convertase and C3b binds Mem.
5) C2bC4bC3b (5 convertase) Cleaves C5
6) ______________ _______ __ __ __ _______
7) Membrane attack complex is formed
Classical Pathway:
1) C1 Binds Antibody (that is bound to the Bacteria mem.)
2) C1-Antibody complex cleaves C2 and C4
3) C2b and C4b bind membrane and form C3 Convertase
4) C3 is cleaved by convertase and C3b binds Mem.
5) C2bC4bC3b (5 convertase) Cleaves C5
6) C2bC4bC3bC5b attracts C6 to 9 proteins
7) Membrane attack complex is formed
Alternative Pathway:
Starts from the Spontaneous autocleavage of C3. Factor _ is cleaved by Factor _ and joined to form C3b_b a C3 convertase. C3b_bC3b (5 Convertase) forms and continues cascade til MAC as in Classical.
Alternative Pathway:
Starts from the Spontaneous autocleavage of C3. Factor B is cleaved by Factor D and joined to form C3bBb a C3 convertase. C3bBbC3b (5 Convertase) forms and continues cascade til MAC as in Classical.
Inflammatory Roles of Complement :
C3a and C5a are _________
Mast cell _________- Histamine and Leukotrienes
Vascular Changes: Dilation and _______
C5a: causes leukocyte ______ and chemotaxis
Inflammatory Roles of Complement :
C3a and C5a are anaphylatoxins
Mast cell degranulation - Histamine and Leukotrienes
Vascular Changes: Dilation and Permeability
C5a: causes leukocyte adhesion and chemotaxis
MBL Pathway:
Instead of C1+Antibody, a Mannose Binding Lectin kicks off the same cascade by cleaving C_ and C_.
MBL Pathway:
Instead of C1+Antibody, a Mannose Binding Lectin kicks off the same cascade by cleaving C2 and C4.
Direct Agglutination - Regular Use?
ABO Typing
Indirect Agglutination - Regular Use?
Rh Typing
Passive Agglutination - Regular Use?
RF detection
What is the essence of Serum electrophoresis?
Diffusion of the sample molecules according to their charge / size.
What is the Measured component in Nephelometery?
Various proteins / IC
What is the Measured component Serum in electrophoresis?
Albumin, alpha1, alpha2 and beta, globulins are well as gamma globulins
Densitometry:
Detection and Bases for measurement
Blood protein (globulin) and Size
Radial immunodiffusion and Double immunodiffusion/
What is measured? How?
Antigen-antibody interaction by Precipitation