longhorn2891

The other thing is to be absolutely sure that your enzymes are pure.
Trypsin is very often contaminated with a small amount of chymotrypsin, which will ruin your tests.

This therapy has come to my hospital. Thankfully, our oncologist gave me a heads up. Apparently, the drug manufacturer is strongly suggesting that prescribing doctors communicate with their transfusion services. They even provide cards for the docs to give the patients, that can be presented, should the patient go to a different hospital (I'm envisioning something like a card from the Red Cross that details what antibodies a patient has).
Anywho....since I do not routinely stock DTT, and haven't used it in 20 years, my 'frontline' strategy has been to get a complete phenotype on the patient before he gets his 1st daratumumab treatment this afternoon. I am simultaneously trying to find a supplier and pricing for DTT (anyone, anyone?) to determine if this is something we want to undertake or do we want to send these specimens to our reference lab every time.

I agree with the posters above.
We had a long thread about that but I cannot find it for you.
Conclusion: the gel antiglobulin crossmatch is not enough to detect ABO incompatibility.

The following reference may be pertinent to your question:
2010 Ask the FDA and CLIA Transcript



Ask the FDA and CMS/CLIA
October 11, 2010
AABB 2010 Annual Meeting
Baltimore, Maryland

FDA

Jay Epstein - Director, Office of Blood Research & Review, CBER
Ellen Lazarus - Director, Division of Human Tissues in the Office of Cells, Tissue and Gene Therapy, CBER
Hira Nakhasi - Director, Division of Emerging and Transfusion Transmitted Diseases, Office of Blood Research & Review, CBER
Paul Mied - Deputy Director, Division of Emerging and Transfusion Transmitted Diseases, Office of Blood Research & Review, CBER
Judy Ciaraldi - Consumer Safety Officer, Division of Blood Applications, Office of Blood Research & Review, CBER
Lore Fields - Consumer Safety Officer, Blood & Plasma Branch, Division of Blood Applications, Office of Blood Research & Review, CBER
Sharon O'Callaghan - Program Surveillance Branch, Office of Compliance & Biologics Quality, CBER

CMS

Penelope Meyers - Division of Laboratory Services, Survey & Certification Group, Center for Medicaid & State Operations at CMS

Moderator

M. Allene Carr-Greer, Director, Regulatory Affairs, AABB


Question 4: We perform all routine testing using gel technology. We also perform electronic crossmatches. For patients in whom clinically significant antibodies have been identified, is it sufficient to perform only a gel antiglobulin crossmatch? Does this satisfy the CLIA requirement to perform a test to detect ABO incompatibility?

MS. MEYERS: For this question, before I start, I would like to just make the comment that the answers that I will be giving to the questions today are based on the CLIA regulations. However, I would like to remind the audience that many laboratories choose to obtain their CLIA certification through a CMS-approved accreditation organization, of which there are six. One of which is AABB. These laboratories must follow all the requirements of their chosen accreditation organization which may be more stringent than the CLIA requirements.

Now back to the question. Actually, these CLIA requirements for crossmatching are based on the FDA requirements for crossmatching, and FDA and CMS have collaborated in preparing the answer to this question. The simple answer is that the IgG gel card does not fulfill the requirement to demonstrate ABO incompatibility. There are two issues involved here. First, the labeling clearly indicates that the IgG gel card is for direct and indirect antiglobulin tests. In other words, detection of cell-bound IgG antibodies. While the limitation section of the package insert states that some IgM antibodies may react, this limitation should not be interpreted to mean that the card is capable of detecting all IgM antibodies, particularly ABO antibodies. Secondly, the IgG gel card is a low ionic test system and there have been reports that ABO incompatibilities, due to IgM antibodies, can be missed when the antibodies are weak and the test is low ionic strength. While we acknowledge that there is continuing debate on this topic, but with the knowledge of these reports and in the absence of data from the reagent manufacturer to support the use of a low ionic strength system for detection of ABO incompatibility due to IgM antibodies, we believe it is not appropriate for users to omit some kind of test to detect these incompatibilities. And for eligible patients, an electronic crossmatch would fulfill the requirements. An immediate spin crossmatch, of course, is an acceptable method for all patients.

MODERATOR: Thank you, Penny. Can I ask, because I could not hear everything that you just said, but did you respond to the part about sufficient to perform only the gel antiglobulin crossmatch, that first part?

MS. MEYERS: No, it is not sufficient to perform only the gel antiglobulin crossmatch because that does not fulfill the requirement to detect ABO incompatibilities.
PANEL MEMBERS:

Both the teleconference on changes in the 28th edition of Standards and the Ask the Standards Committee session at the annual meeting left me totally convinced that a computer system can fill this bill. They were clear that you have to have validated it on site. Obviously you have to have IS xm added to your downtime procedures since EXM won't be available for patients with no antibodies and you will have to do it in addition to gel testing on those that do have antibodies. I added a description of my logic to my procedure explaining the the computer is at least as sensitive and specific as the IS xm since it can't have false positives due to cold agglutinins and rouleaux and it can't have false negatives due to weak reverse antibodies, problems which can plague IS xms.