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 only 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