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UNT / Biological Sciences / BIOL 4201 / What is opsonization?

What is opsonization?

What is opsonization?

Description

School: University of North Texas
Department: Biological Sciences
Course: Immunology
Professor: Goven
Term: Winter 2016
Tags: immunology, Study Guide, and Test 2
Cost: 50
Name: Test 2 Study Guide
Description: Here is my study guide for test 2!
Uploaded: 03/07/2016
6 Pages 144 Views 4 Unlocks
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Test 2 Study Guide


What is opsonization?



Functions of Antibodies 

∙ Neutralize toxins

o Bacterial, venom

o Ab binds to active site on Ag  

∙ Agglutination (Aggregation)

o Ab binds to two Ag’s  

o Clumps them together (like eating popcorn)

o Phagocytic cell can attack two cells at once

∙ Opsonization

o Prepare to eat (like mustard on a hot dog)

o Puts an Ab “handle” on Ag  

∙ Viral neutralization

o Cover binding site with Ab

o Like bacterial neutralization, but multiple Ab covering binding  sites

∙ Antibody Dependent Cell Cytotoxicity (ADCC)

o Ab is an identifier for phagocytic cells to lyse


What is neutralize toxins?



Complement 

∙ Necessary to lyse cells – Ab cannot lyse cells on their own

∙ Found in serum

∙ Heat labile (denatured at 56C for ½ hr)

∙ Constant concentration—wait for Ab as the magic bullet

∙ 9 proteins, work in cascade form

o C1, C4, C2, C3, C5, C6, C7, C8, C9

o Glycoproteins, enzymes cleave them to make products If you want to learn more check out What is griffith?

o Source: liver, monocytes, macrophages

o Function: lyse target cells, mediate inflammation, enhance  phagocytosis, recruit cells for proliferation in bone marrow

2 Pathways of Complement 

Classical: must have Ab activation, 3 phases


What is antibody dependent cell cytotoxicity (adcc)?



If you want to learn more check out What is pahoehoe?

Alternate: no Ab necessary

Classical 

1. Recognition- Ab-Ag complex, two IgG or one IgM bind C’1 esterase 2. Enzyme Activation- conformational change in C’1 esterase a. Splits C4  

i. C4a denatures in the fluid

ii. C4b binds to the membrane (but only 10%)

b. C1 esterase also splits C2 after C4b binds

i. C2a binds  

ii. C2b denatures

c. C3 convertase splits C3

i. C3a enters fluid, is biologically important  

ii. C3b binds  

iii. Causes immune adherence

1. Ag with C3b attaches to rbc, travels to spleen, meet  

splenic macrophage,

iv. Causes opsonization

1. Ag with C3b is phagocytized by phagocytic cell

v. Wouldn’t notice immunodeficiency at this point

3. Attach Phase

a. C5 convertase splits C5  

i. C5a same fxn as C3a

ii. C5b binds anywhere on the membrane

b. C6, C7 attach—chemotactic function

c. C8, C9 attach—cause leaky membrane, incomplete tube

d. C5b-C9 attach—causes lysis of cell, fully functional tube

i. When there are too many tubes on the cell, it becomes leaky  and unstable, and becomes lysed  

ii. Tube is hydrophilic on the ends, hydrophobic within the  

membrane

∙ Anaphylatoxic Activity  

o C3a and C5a directly affect vasculature without mast cells If you want to learn more check out What is foreign markets?
Don't forget about the age old question of Referring to biologically-driven growth is called what?

o Increase vascular permeability

o Release of histamine  

∙ Chemotactic Activity

o Bring white blood cells to site of infection using concentration gradient in  tissue  

Alternate 

∙ Different beginning  

∙ Factor B + C3b = C3bB + Factor D = C3bBb (unstable enzyme) + C3 = C3a  and C3b

∙ Need to stabilize C3bBb with properdin (P): compound that lyses cells  without Ab

∙ PC3bBb is a stable enzyme, acts on large amounts of C3

o C3a same as classical

o C3b binds to PC3bBb and produces PC3b2Bb

∙ PC3b2Bb cleaves C5 – then it’s the same as the classical pathway If you lack Properdin, you will have more frequent infections.

Ag will have a free run during the lag phage while waiting for the production of Ab  and the classical pathway.

Genetic Control of Immune Response Don't forget about the age old question of What are the two ways o2 is transported in blood?
Don't forget about the age old question of What was the role of the catholic church and christianity during the colonial period?

∙ Gene editing: gene rearrangement and excision  

∙ Somatic point mutations: improves diversity of Ab binding sites ∙ Plasma cells can switch isotypes: B – PC – IgM then switch to IgG

Infection Example 

∙ Primary Response

o 0-7 days: lag phase

o Clonal selection, clonal expansion, cell differentiation, protein  synthesis, export of Ab

o IgM produced first, then large amounts of IgG

Reinfection 

∙ Secondary Response (Anamnestic)

o Shorter lag phase: 2.5 days because of memory cells

o More powerful

o Higher levels of IgG produced  

Immunogenetics

∙ Dreyer/Bennet 1965  

∙ Two genes, one polypeptide chain

∙ Choose a variable and a constant gene, cut out others

Immunobiology Experiments

∙ T cell, B cell, macrophage and cytokine cooperation

∙ Good/Waksman experiment proves you need T, B, macrophage o thymoma in cancer patient, undergoes thymectomy (ThyX)

o Patient develops hypogammaglobulinemia  

o Use symgeneic mice (genetically identical)  

 Add reconstituted thymoctyes—good Ab response

∙ Claman: proves what cells make Ab

o 1. X-ray mice—kills lymphocytes but not macrophages

o 2. Add Thymocytes  

o 3. Add Ag

o Ab Response: negative. Proves that T cells don’t make Ab  

∙ X-rayed mouse with added thymoctyes and Ag: no Ab response ∙ X-rayed mouse with added bone marrow cells and Ag: medium Ab response ∙ X-rayed mouse with added thymoctyes AND bone marrow cells and Ag: good  Ab response

Macrophages

∙ Process Ag, ingest and digest Ag into its antigenic determinants ∙ Present Ag to lymphocytes

∙ Experiment: Can separate macrophages from lymphocytes because MP  adhere to sides of test tube

∙ T and B cells produce Ab response

∙ T and B and macrophages produce a protective Ab response  Major Histocompatibililty Complex- Antigen Bridge 

Nonspecific molecules that bind Ag

Class I: surface glycoprotein, on all nucleated cells, fxn. Describe self, present  ENDOGENOUS Ag

Ex. Ag bridge between T cytotoxic lymphocyte and Tumor Cell

∙ T cell has TCR receptor region that binds to Tumor Associated Antigen on  Tumor Cell

∙ T cell has CD8 marker that binds to CD8 receptor on Tumor Cell

Class II: surface glycoprotein, on Ag presenting cells only, fxn. Describe self,  present EXOGENOUS Ag, promiscuous – will bind anything, no specificity  

Ex. Ag bridge between T helper cell and Macrophage

∙ T helper cell has TCR that binds to processed Ag on Macrophage (Antigen  Presenting Cell)

∙ T helper cell has CD4 marker that binds to CD4 receptor on Macrophage  

T and B Cell Cooperation

Carrier Effect: Hapten-carrier  

∙ Experiment: Hapten is Dinitrophenol (DNP), Carrier is Bovine Gamma Globulin (BGG)

∙ EA is a different carrier: Egg Albumin

Using four mice:

Addition of Ag

Add DNP-BGG

Add DNP-BGG

Add DNP-BGG

Add DNP-BGG

Antibody  

response to  

DNP

Primary

Primary

Primary

Primary

2nd Exposure

Add DNP-BGG

Add BGG

Add DNP-EA

Add EA

Antibody  

response to  

DNP

Secondary

None

Primary

None

Contains 2nd B  cells, and 2nd T cells

Contains 2nd B  cells, but only  1st T cells

∙ B cells recognize the hapten, T cells recognize the carrier.

∙ A different carrier means only a primary response by T cells.

Overcoming the Carrier Effect 

∙ Need T and B cells to be in equal concentration to overcome the carrier effect in the body

Using two mice:

Add the antigen

Add DNP-BGG

Add EA

Produce a single cell  

suspension

Add anti-CD4 and anti CD8 to mark T cells, add  C’ to lyse T cells, and  remove macrophages by  adherence

Add antimouse IgD to  mark B cells, add C’ to  lyse B cells, and remove  macrophages by  

adherence

B cells remain

T cells remain

X-ray a new mouse  

(will retain  

macrophages)

Add B cells with DNP-BGG memory

Add T cells with EA  

memory

Add DNP-EA and measure Antibody response

Ab response is secondary: the new mouse has  memory to DNP from the B cells and memory to EA  from the T cells

Cytokines

∙ Small and soluble  

∙ Found in body fluids

∙ Secreted by white blood cells (lymphocytes, monocytes)

∙ Affect gene expression by causing cell to produce proteins

o Ex. Plasma cell producing Antibody

∙ Activate cells to proliferate and differentiate

∙ Send specific signals

∙ Concentration depends on number of T cells

Types of signaling

∙ Autocrine: self

∙ Paracrine: Neighboring

o High concentration not necessary  

∙ Endocrine: distant  

o Needs carrier protein

o Ex. Cytokine to bone marrow to promote lymphocyte production Cytokine Function:

∙ Pleiotropic: some have multiple effects

∙ Synergistic: some effects need two cytokines at once

∙ Redundant: multiple cytokine types do the same thing

∙ Antagonistic: different cytokines can turn off others

T Delayed Hypersensitivity Type

∙ Similar to the function of a T helper cell with a CD4 marker ∙ Ex. Tuberculosis test: purified protein derivative of TB inserted under the skin

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