exam 4: diagnostics, cancer immunology

Question 1

describe the difference between a product that used polyclonal Ab and one that uses a monoclonal Ab

Answer 1

polyclonal Ab has high affinity, low specificity
monoclonal Ab better for specificity

Question 2

nonspecific absorption, nonpathologic Ab rxn, binding to FcR, contamination, internally bound Ig detected, inappropriate cut off or recent transfusion can all lead to what type of test?

Answer 2

false positive

Question 3

low reactivity, low affinity Ab, inappropriate Ab:Ag ratio, steric hindrance, inappropriate cut off, cell-mediated cytopenia, Ab vs precursor not cell, drug dependant or steroid administration can all lead to what type of test

Answer 3

false negative

Question 4

Radioimmunoassay (RIA)

Answer 4

detects serum antigens, good for low concentrations
(+) if serum is infected, decreased radioactivity
(-) if serum is not infected, increased radioactivity

Question 5

Direct Coombs Test

Answer 5

detects IgG, IgM or C3 bound to RBC
tests of immune-mediated hemolytic anemia (IMHA)

Question 6

ELISAs

Answer 6

enzyme-linked immunosorbent assay
test for complement, Ab, or Ag
indirect: primary Ab that detects Ag, then a secondary enzyme conjugated Ab that detects primary Ab
direct: an enzyme conjugated antibody that detects patient antibody

Question 7

immunochemistry

Answer 7

can localize antigen to area of tissue damage
species specific
detects Ag in situ
deparaffinize & Ag retrieval with block, primary Ab and secondary Ab

Question 8

immunohistochemistry

Answer 8

antigens on tissue sections rather than single cell suspensions

Question 9

immunofluorescent assay (IFA)

Answer 9

small quanities of antigen or antibody easier to detect

Question 10

flow cytometry

Answer 10

detects cell-specific antigens & can indicate cell state
cellular antigens, cellular products, cell cycle analysis, cell types, cellular viability & vitality

Question 11

Answer 11

side scatter = complexity of cell
forward scatter = size of cell

Question 12

immunoelectrophoresis

Answer 12

differentiation between groups of plasma proteins
albumin (smallest)
acute phase proteins (alpha & beta globulins)
immunoglobulins (gamma globulins)

Question 13

what are a couple important beta-globulins in non-domestic species

Answer 13

fibrinogen
amyloid A
C-reactive proteins

Question 14

immunofixation

Answer 14

separates isotypes of immunoglobulins
detects Ig light chains (kappa/lambda)

Question 14

immunofixation

Answer 14

separates isotypes of immunoglobulins
detects Ig light chains (kappa/lambda)

Question 15

acute serum vs convalescent serum

Answer 15

acute serum: initial sample, usually will show IgM with acute infection

convalescent serum: later sample, IgG would increase with the active disease process and you would see a 4-fold increase in Ab titers

Question 16

how do you determine if an antibody titer has a strong reaction/many antibodies present

Answer 16

the greater the dilution the better (e.g. 1:64)

Question 17

define premunition

Answer 17

an antibody is present but may not completely clear an infection

Question 18

is hyperplasia reversible

Answer 18

yes

Question 19

types of cancers
epitheial tumors are ___
mesenchymal tumors are ___
round cell tumors are ____

Answer 19

adenomas, carcinomas
sarcomas
lymphoma, plasma cell tumor, histiocytoma, mast cell tumor, transmissible venereal tumor

Question 20

proto-oncogens

Answer 20

mutation enhances function
(e.g. growth factors, growth factor receptors, signal transduction proteins, gene transcription proteins)

Question 21

tumor suppressor gene

Answer 21

example: P53 or Rb
mutation leads to loss of function

Question 22

what causes neoplastic transformation of cells

Answer 22

break down in DNA repair processes
uncontrolled growth
inhibition of apoptosis
alteration in tumor microenvironment (e.g. angiogenesis which allows cancer to receive blood supply)
immune evasion

Question 23

how does slow initial growth of cancer evade the immune system

Answer 23

cancer cells are not detected

Question 24

what cytokine is released for immune silencing & cancer stem cell proliferation

Answer 24

PGE2

Question 25

how do cancer cells escape treatment/therapy? what does this allow?

Answer 25

highly competitive clone
causes enhanced tumor growth

Question 26

how do tumor associated macrophages help cancer evade immune system?

Answer 26

immunosuppress the tumor environment

Question 27

what do FKN, ATP, LTF allow

Answer 27

tumor proliferation, trophic support, pro-angiogenic proliferation and anti-apoptosis

Question 28

what do cancer cells do to not undergo apoptosis

Answer 28

breakdown of normal mechanisms, such as CD8+ t cells, gamme:delta t cells, NK cells

Question 29

how does decreased expression of MHC class I help cancer cells evade immune system

Answer 29

masks tumor antigens & gives antigens lower affinity interactions with CTLs

Question 30

what types of cytokines do cancer cells cause the release of

Answer 30

anti-inflammatory like TGF-beta or Treg recruitment to suppress immune response

Question 31

what inhibitory proteins are expressed to help cancer evade immune system

Answer 31

PD-L1 and PDL-2

Question 32

what secondary signal is lacked to allow cancer cells to evade immune system

Answer 32

lack of B7 on APC (dendritic cell) so co-stimulation with CD28 doesn’t occur= anergic T cells