Direct Test Labeled anti-X antibody Detectable marker Wash off Positive result Label detected. unbound antibodies. Test for label. Conclusion: Antigen X is present. Labeled antibodies bind to antigen. Labeled antibodies remain. Unknown Add labeled antigen antibodies specific for antigen X. Unknown antigen is attached to a solid surface. Wash off unbound antibodies. Negative result Label not detected. Test for label. Labeled antibodies do not bind. Labeled antibodies washed off. Conclusion: Antigen X is not present (a) Indirect Test Detectable marker Labeled anti-human Patient's Add labeled IgG antibody antibody (IgG) secondary antibodies (anti-human IgG); wash off any that do not bind. Wash off unbound Test for Positive result Label detected. Conclusion: Patient's serum has IgG against antigen X. label, antibodies. Patient's antibodies bind to antigen. Patient's antibodies remain. Labeled secondary antibodies bind to patient's IgG and remain. Add patient's Antigen X serum (contains antibodies). Add labeled secondary antibodies (anti-human IgG); wash off any that do not bind. Antigen X is attached to a solid surface. Wash off unbound antibodies. Test for Negative result label. Label not detected. Conclusion: Patient's serum does not have IgG against antigen X. Patient's antibodies do not bind. Patient's antibodies washed off. No human IgG, present so labeled secondary antibodies do not bind. (b) FIGURE 18.5 Basic Principles of Tests That Use Labeled Antibodies to Detect Antigen-Antibody Interactions (a) Positive and negative results of a direct test. (b) Positive and negative results of an indirect test.
Direct Test Labeled anti-X antibody Detectable marker Wash off Positive result Label detected. unbound antibodies. Test for label. Conclusion: Antigen X is present. Labeled antibodies bind to antigen. Labeled antibodies remain. Unknown Add labeled antigen antibodies specific for antigen X. Unknown antigen is attached to a solid surface. Wash off unbound antibodies. Negative result Label not detected. Test for label. Labeled antibodies do not bind. Labeled antibodies washed off. Conclusion: Antigen X is not present (a) Indirect Test Detectable marker Labeled anti-human Patient's Add labeled IgG antibody antibody (IgG) secondary antibodies (anti-human IgG); wash off any that do not bind. Wash off unbound Test for Positive result Label detected. Conclusion: Patient's serum has IgG against antigen X. label, antibodies. Patient's antibodies bind to antigen. Patient's antibodies remain. Labeled secondary antibodies bind to patient's IgG and remain. Add patient's Antigen X serum (contains antibodies). Add labeled secondary antibodies (anti-human IgG); wash off any that do not bind. Antigen X is attached to a solid surface. Wash off unbound antibodies. Test for Negative result label. Label not detected. Conclusion: Patient's serum does not have IgG against antigen X. Patient's antibodies do not bind. Patient's antibodies washed off. No human IgG, present so labeled secondary antibodies do not bind. (b) FIGURE 18.5 Basic Principles of Tests That Use Labeled Antibodies to Detect Antigen-Antibody Interactions (a) Positive and negative results of a direct test. (b) Positive and negative results of an indirect test.
Chapter16: Antifungal, Antiviral, And Immunizing Agents
Section: Chapter Questions
Problem 24RQ
Related questions
Question
In (b), why would it be more efficient to use labeled anti-human IgG rather than label the patient’s antibodies?
Transcribed Image Text:Direct Test
Labeled
anti-X
antibody
Detectable
marker
Wash off
Positive result
Label detected.
unbound
antibodies.
Test for label.
Conclusion:
Antigen X is
present.
Labeled
antibodies
bind to antigen.
Labeled
antibodies
remain.
Unknown
Add labeled
antigen
antibodies
specific for
antigen X.
Unknown antigen is
attached to a solid
surface.
Wash off
unbound
antibodies.
Negative result
Label not detected.
Test for label.
Labeled
antibodies
do not bind.
Labeled
antibodies
washed off.
Conclusion:
Antigen X is
not present
(a)
Indirect Test
Detectable
marker
Labeled anti-human
Patient's
Add labeled
IgG antibody
antibody
(IgG)
secondary
antibodies
(anti-human IgG);
wash off
any that
do not bind.
Wash off
unbound
Test for Positive result
Label detected.
Conclusion:
Patient's serum
has IgG against
antigen X.
label,
antibodies.
Patient's
antibodies
bind to antigen.
Patient's
antibodies
remain.
Labeled secondary
antibodies bind to
patient's IgG
and remain.
Add patient's
Antigen X
serum
(contains
antibodies).
Add labeled
secondary
antibodies
(anti-human IgG);
wash off any that
do not bind.
Antigen X is attached
to a solid surface.
Wash off
unbound
antibodies.
Test for Negative result
label.
Label not detected.
Conclusion:
Patient's serum
does not have IgG
against antigen X.
Patient's
antibodies
do not bind.
Patient's
antibodies
washed off.
No human IgG,
present so labeled
secondary antibodies
do not bind.
(b)
FIGURE 18.5 Basic Principles of Tests That Use Labeled Antibodies to Detect Antigen-Antibody Interactions (a) Positive and negative
results of a direct test. (b) Positive and negative results of an indirect test.
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