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Immunology (By: Ben + Dustin) > Seminars 1/2 (Ben) - Intro + Ag/Ab Tests > Flashcards

Seminars 1/2 (Ben) - Intro + Ag/Ab Tests Flashcards

1
Q

What are the 4 main features of adaptive immunity?

A
  1. Specificity
  2. Sensitivity - small amt antigen can trigger
  3. Memory
  4. Selectivity - cell clone with appropriate receptor for antigen will proliferate more
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2
Q

What are the prefixes for 3 types of antigens according to their origin?

A
  • Auto - self antigen
  • Allo - non-self but same species
  • Xeno - non-self, different species
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3
Q

What is the basic difference between the epitopes bound by TCRs and BCRs?

A
  • BCR - binds conformational epitopes on unprocessed, whole antigen molecules
  • TCR - binds linear epitopes presented on MHC after APC processing
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4
Q

What happens if bone marrow has a functional defect?

(this was presented as an MCQ on the seminar PPT… maybe test material)

A
  • amt of circulating blood cells is reduced (pancytopenia) and severe, recurrent infections occur
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5
Q

What happens if a baby loses their thymus during a surgical procedure?

(another PPT MCQ)

A
  • Peripheral T cell function may be affected, leading to early immune senescence
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6
Q

What is immunophenotyping?

A
  • specific labeling of surface/intracellular markers to identify a cell population
  • done with Ag-AB reactions
  • can help identify leukocyte subpopulations, as well as their functional/developmental states
  • mostly looks for CD (Cluster of Differentiation) molecules
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7
Q

What CD molecule is common to all T cells?

How does its cellular location change over the course of T cell maturation?

A

CD3

  • transitions from intracellular icCD3 to normal CD3 on the cell membrane between “early thymocyte” and “common thymocyte” stages
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8
Q

What CD molecule is common to all NK cells?

(both NKT and regular NK)

A

CD56

(NKT is CD3+, NK is CD3-)

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9
Q

What CD molecule is present on all B cells?

A

CD19

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10
Q

What is a consequence of lymph node removal?

(another PPT MCQ)

A
  • lymphedema can develop as a result of disturbed lymph drainage
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11
Q

What are the different parts of a lymph node and the types of cells in each?

A
  • Paracortex - T + dendritic cells
  • Cortex - B cells + macrophages
  • Germinative Center - dividing B cells, plasma cells + macrophages
  • Follicle - B cells
  • Medulla - plasma cells + macrophages
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12
Q

Through what special kind of blood vessel do lymphocytes enter secondary lymph organs?

A

High Endothelial Vessels

  • in all secondary lymph organs except spleen
  • cuboidal endothelial cells with receptors for leukocyte interaction
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13
Q

What is a sentinel lymph node?

A
  • the first lymph node in a lymph node bed to receive drainage from a tumor
  • “staging” of cancers is based on sentinel node biopsy
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14
Q

What is the consequence of a splenectomy?

(another PPT MCQ)

A
  • susceptibility to infections with encapsulated bacteria and immune memory reduction
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15
Q

What are the two types of mucosa-associated lymph tissue (MALT) and examples/locations of each?

A
  • GALT (GI-associated) - tonsils, appendix, Peyer’s patches
  • BALT (broncheoalveolar) - in lung parenchyme + bronchi
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16
Q

What is the consequence of a tonsillectomy?

(PPT MCQ)

A
  • there is no direct immunological consequence
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17
Q

What is the total count of WBCs per liter of blood?

A

Men: 3.7 - 9.5 x 109 / L

Women: 3.9 - 11.1 x 109 / L

18
Q

What are the lymphocyte counts in blood per liter?

Overall and for specific types.

A
  • Total: 1.1 - 3.5 x 109
  • T: 0.7 - 2.7 x 109
  • B: 0.06 - 0.66 x 109
  • NK: 0.2 - 0.4 x 109
19
Q

What are the granulocyte counts in blood per liter?

Overall and for each type.

A
  • Total: 1.8 - 8.9 x 109
  • Neutr: 1.5 - 7.4 x 109
  • Eos: 0.02 - 0.67 x 109
  • Baso: 0 - 0.13 x 109
20
Q

What is the monocyte count in blood per liter?

A

Monocytes: 0.2 - 0.9 x 109

21
Q

What kind of bonds form between antigens and antibodies?

A
  • many non-covalent bonds = strong connection
  • H bonds, ionic bonds, VdW interactions + hydrophobic interactions
  • is irreversible
22
Q

What are polyclonal vs. monoclonal antibodies?

A
  • Polyclonal - different antibody products of different B-cell clones recognizing different epitopes on the same antigen, normally produced in physiological immune response
  • Monoclonal - antibodies specific to a single epitope, from a single B cell clone, sometimes produced in disease
23
Q

What is affinity in terms of antibodies?

How is it quantified?

A
  • how strongly an antibody fits to its antigen
  • expressed in terms of the equilibrium constant of the Ag-Ab complex
    • Keq = [Ag-Ab] / [Ag] x [Ab]
24
Q

What is avidity in terms of Ag-Ab interactions?

A
  • combined strength of all bond interactions btwn an Ab and its Ag
  • ex: pentameric IgM with binding several epitopes on the same antigen has higher avidity than monomeric IgG with just one or two epitopes bound
25
Q

What is serum electrophoresis and what is it for?

A
  • separation of serum proteins via an electrical current, based on their electrical charge
  • used primarily to diagnose myelomas or gammopathies
26
Q

How does a normal serum electrophoresis densitogram look?

How does it change in myeloma and polyclonal gammopathy?

A
  • Normal: largest spike is albumin, gamma globulins are a low hump
  • Polyclonal: a taller, but still broad, y-globulin hump
  • Myeloma: an M-spike in the gamma region
27
Q

What happens to a serum electrophoresis densitogram in case of chronic liver failure and chronic inflammation?

A
  • liver failure: a relative decrease in albumin and alpha/beta globulins, increase in gamma-glob.
  • inflammation: a relative albumin decrease, with an acute phase protein + Ig increase showing in the alpha, beta + gamma bands
28
Q

What are some disease cause by immune complex overproduction ?

A
  • Via endogenous ABs: ABO/RH incompatibility, hemolytic anemia + SLE
  • Via exogenous ABs: “serum sickness” caused by a reaction to exogenous antibody administration (e.g. allergic reaction to an antivenom)
29
Q

What is the difference between turbidometry and nephelometry?

A

Both measure levels of proteins in liquid samples (serum, CSF, etc.)

  • Turbidometry - measures light intensity which makes it directly thru a sample (lower sensitivity)
  • Nephelometry - measures light intensity which is scattered by a sample (higher sensitivity)
30
Q

What is precipitation in terms of immunological reactions?

What is required for normal precipitation to occur?

(in terms of Ag/Ab concentrations)

A
  • soluble antigens forming soluble Ag-Ab complexes can be made insoluble/visible in the lab via physical (decreased temp.) or chemical (polyethylene glycol) methods
  • requires similar Ag/Ab concentrations (equivalence)
31
Q

What factors affect precipitation?

(3)

A
  1. Valence - # of “arms” by which Ab can bind Ag (IgM pentamer vs. IgA dimer)
  2. Temperature - lower temp. encourages precip.
  3. Chemical Factors - solubility-decreasing substances such as PEG
32
Q

What is the “Reynaud phenomenon”?

A
  • bluish-black tips of digits due to precipitation of circulating immune complexes at lower temps
  • common in immune diseases with incr. circulating complexes
33
Q

Describe simple radial immunodiffusion.

A

AKA Mancini method

  1. Patient sample loaded into wells of gel containing Ab specific to Ag in question
  2. Ag diffuses into gel + forms ring of precipitate where [Ag] = [Ab]
  3. Diameter is proportional to log [Ag]
34
Q

Describe double radial immunodiffusion.

A

AKA Ouchterlony method

  1. Ag and Ab placed in seperate wells in gel + diffuse toward each other
  2. Precipitate line forms where [Ag] = [Ab]
  3. If [Ag] in sample is higher, Ag will move further toward Ab well + thus dilute to match [Ab] (and vice versa)
35
Q

Describe immunoelectrophoresis.

A
  • Patient + control serums are applied to separate round wells in gel on opposite sides of a long, narrow well
  • Serum proteins are electrophoretically separated
  • A complete polivalent Ab set from diff organism (eg horse) is applied to long well
  • Sample serum proteins diffuse towards Abs + form multiple arcing precipitate bands in gel
  • Can compare size, density + positioning of control bands to sample bands to look for increased concentrations, etc.
36
Q

Describe immunofixation + its purpose.

A

To detect a specific antibody isotype (antibodies in sample are the antigens for the experimentally applied antibodies):

  • Same sample (urine, serum, etc.) is run thru electrophoresis in 6 lanes
  • “Monospecific” antibodies for each type of Ab heavy + light chain (mu, alpha, gamma, kappa, lambda) are each applied to a lane
  • Precipitates form where the sample’s elevated ABs react with the applied ABs (ex: if IgG-lambda is elevated, precipitate forms in the gamma + lambda lanes)
37
Q

What is an antibody titer?

A
  • a test for the maximal dilution of an Ab solution that will still give a positive agglutination result when combined with a fixed amt of antigen
  • the result is expressed as the inverse of the dilution (in pic below result = 160)
38
Q

What is direct vs. indirect agglutination?

A
  • Direct - binding of primary antibodies with antigens of cells results in agglutination
  • Indirect - secondary antibodies bind to Fc region of primary ABs against cellular antigens + induce agglutination
39
Q

What is passive agglutination?

What are 2 examples of lab tests using this method?

A
  • Latex beads without surface antigens are coated with a known antigen or antibody + mixed with serum to check for presence of Ab/Ag
  • Tests for r__heumatoid factor (serum IgM autoantibodies against self IgG) and CRP use passive agg.
40
Q

What are the structures of the ABO antigens?

A
  • O antigen - has terminal galact-/fucose sugars
  • A antigen - an N-acetyl-galactosamine on O Ag
  • B antigen - a galactose on O Ag
41
Q

Describe the microcolumn test.

What is it for?

A

Tests the amount of ABO antibodies in patient serum with known cells/antigens or vice versa

  • Add sample + knowns to microcolumn containing anti-IgG, anti-IgM and anti-C3d (help indirect agglutination)
  • Sepharose beads at bottom of well will catch agglutinated complexes upon centrifugation (+ result) or non-agglutinated cells will flow to bottom (- result)
42
Q

How can hemmaglutination occur without antibodies?

A

Viral proteins (eg mumps, flu) can induce agglutination

Immunology (By: Ben + Dustin) (12 decks)

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