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
Panagglutinin All Capture Panel Cells Reacting Automated Positive Negative DAT Perform Perform PEG panel eluate or workup as WAI All Cells Identify All Cells Negative antibody Reacting AHG XM with PEG Autocontrol Positive Negative Work up for Workup multiples or as WAI high freq
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”
Positive Solid Phase Antibody Screen Solid Phase Positive Negative Panel Report Identify PEG Antibody Antibody? Screen No Positive Negative PEG Panel Echo only antibody Positive Negative Identify IS XM Report Antibody of no No Antibody? Antibody discernible specificity – treat as clinically sig
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
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