Unexpected Antibody Reactions What is this and what do I do with it? - - PowerPoint PPT Presentation

Unexpected Antibody Reactions

What is this and what do I do with it?

Janet Cass-Baxter, MT(ASCP)SBB

Objectives

• Discuss positive antibody screen and

pan-reactive workflows

• Discuss tools for resolving the

“unresolvable” non-specific reaction patterns and the pan-reactive reaction patterns

Anne Arundel Medical Center

• 380 bed hospital
• Third busiest hospital in Maryland
• Active Oncology, Mother/Baby with a

NICU (second most active maternity service in Maryland), Orthopedics

• Open heart is in the works
• Have our own Donor Center that

supplies 100% of our RBC needs

The Unexpected

• We expect to put our sample into the

instrument and get a definitive answer back

• Most of the time that is what happens
• But what if that doesn’t happen?
• What are the next steps in resolution?

Antibody Screen

• Antibody Screen positive – proceed to solid phase panel
• Antibody screen has question marks??????

Probably negative, do a manual screen (PEG) to resolve

• Antibody Screen has a question mark, and a strong positive

reaction

Probably negative, do a manual screen (PEG) to resolve

• Antibody screen all strong positive reactions – but they do not

have a smooth consistency, they are granular looking



Automated panel may come up all positive, with that granular look



Automated panel may come up negative



PEG panel will be negative (probably)

Panel Weak Panagglutinin

• If the panel gives you a bunch of

question marks – probably all negative

• I would go to a PEG antibody screen

and see what that says. It will probably be negative. If not, proceed from there.

Panel Strong Panagglutinin

• Everything is positive
• now what?

 Can’t assume too much…yet, and the objective is not to just

make it go away. The objective is to identify what is there.

 Warm autoimmune antibody?  Multiple alloantibodies?  Junk?

Panel Panagglutinin

• Run an automated DAT

 If positive – move to a manual workup as if

this is a warm auto antibody

 If negative

 Might run an Extend panel to see if that offers any

more information OR…

 Move to manual PEG panel to see what

information that offers

Panel Panagglutinin

 PEG panel completely negative

 What we call an Echo only antibody  We define this as something that reacts only with

the solid phase and doesn’t react with PEG or LISS

 We do a complete XM with PEG – although the

antibody doesn’t react in PEG so this will undoubtedly be negative

Panel Panagglutinin

 Add a comment that says

“Alloantibody with possible clinical significance

• identified. Antibody is of such weak titer that we

cannot assign specificity at this time. Antibody will be treated as clinically significant until proven otherwise.”

Panel Panagglutinin

 PEG panel yields a discernible pattern –

Antibody ID’d

 PEG panel results – all positive

 Open up the bag of tricks and start applying them

 Enzymes  Adsorptions  Phenotyping of the patient  Search for negative cells to high freq antibodies

Automated DAT Positive Negative Perform eluate or workup as WAI Perform PEG panel Identify antibody All Cells Reacting Autocontrol All Cells Negative AHG XM with PEG Negative Positive Workup as WAI Work up for multiples or high freq Panagglutinin All Capture Panel Cells Reacting

Panel Pos, but no pattern

• Run an Extend panel to gather more

information

• Move to PEG manual panel to resolve

 If PEG is negative then we assign our Echo

• nly antibody identification to it.

 If PEG is positive and you can get an ID, great  If PEG is positive and you don’t get a pattern

you may do further investigation or call it a “no discernible specificity”

No No Positive Solid Phase Antibody Screen Solid Phase Panel Negative Positive PEG Screen Negative IS XM Positive Identify Antibody? PEG Panel Identify Antibody? Antibody of no discernible specificity – treat as clinically sig Report Antibody Report Antibody Echo only antibody Positive Negative

Case Study #1

Echo Ab screen

Case Study #1

Echo panel

Case Study #1

• Run a DAT – solid phase
• Positive DAT
• No history of transfusion
• Call it a warm auto and proceed with

tube testing per protocol

Case Study #2

Echo Ab screen

Case Study #2

Echo panel

Case Study #2

• Echo Dat is negative
• No transfusion history
• Tube PEG panel

Case Study #2

Tube PEG panel – no discernible specificity

Case Study #2

Conclusion

• Solid phase - panagglutinin
• PEG panel – all clinically significant

alloantibodies ruled out

• Negative auto control
• Result as “NDS”
• PEG/AHG crossmatches

Case Study #3

Echo Ab screen – no INT

Case Study #3

Echo panel – no INT

Case Study #3

PEG screen

Case Study #3

PEG panel – anti-E

Case Study #4

Echo Ab screen

Case Study #4

Echo Panel

Case Study #4

Conclusion

• Result as Negative
• IS crossmatch