DAT testing

[hmust1]

Hello all -

Currently when we perform an adult DAT, we start with Poly-specific IgG, C3d. If that is positive, we perform both anti-IgG and anti-C3d,C3b. Are there regulations that say I HAVE to perform the anti-complement portion?

I'd like to discontinue the anti-complement reagents to save costs.

Thanks!

Heather

[KBBB]

I searched in the previous threads and didn't find an answer to this either. There were only 2 ordered DAT's at our facility in the last year, and just a few transfusion reaction workups. We could:

1. Send all DAT's out to the local ref. lab. (thus getting rid of Poly AHG and anti-C3d,C3b (this facility had not previously had the C3d,C3b check cells....which is deficient, and none of the previous inspectors noticed-JCAHO-inspected).

2. Keep Poly AHG and do a DAT screen...sending out any positives to the ref. lab.

Is it considered incomplete on the CAP survey to do some but not all types of DAT's?

Note that our facility does not have an OB service.

I'm interested in what others have done in this situation and your opinions.

Thanks

[Lcsmrz]

I don't think there is a regulation that says you have to use Anti-C3, but it's a good idea! When a physician orders a DAT, the usual expectation is that both IgG and complement will be included. It's also very useful in post-reaction workups.

I know the thinking: C3-coated check cells are expensive. But it's worth having them for the above reasons.

[cindym]

Just wanted to say Hello. I'm really enjoying everyone's posts and hope to chime in soon....

[John C. Staley]

Try this on for size.

Keep the poly and IgG coombs and drop the C3d/C3b. Test with poly, if positive, test with IgG. If the IgG is negative then by default it must have been the C3d portion of the poly that reacted therefore you have a positive DAT due to compliment.

Seems logical to me.

Not what we do but might consider some day.

[n.peters]

If anyone was looking for complement requirements see below:

TRM.40655 When a DAT is ordered b a patient's physician, does the testsystme llow detection of RBC-bound complement as well as IgG?

Also TRM.41850 was revised and the only thing I can tell that was changed was a sentence in the note: The DAT must allow detection of RBC-bound complement as well as IgG.

[csjuarez]

Try this on for size.

Keep the poly and IgG coombs and drop the C3d/C3b. Test with poly, if positive, test with IgG. If the IgG is negative then by default it must have been the C3d portion of the poly that reacted therefore you have a positive DAT due to compliment.

Seems logical to me.

Not what we do but might consider some day.

Seems logical to me, too. However, I have seen some cases where the poly was positive (most likely very weakly positive) and both the anti-IgG and anti-C3 were negative. If using the scenario above an incorrect conclusion might be drawn.

[BloodBank]

This is how we handle Poly DAT and Complement CC issue. Beacause of cost & few times test being done, we changed our policy. We perform DAT using anti-IgG when we have positive antibody screen and for cord/ neonatal blood. Poly specific coombs test is performed for suspected transfusion reaction and physician requested coombs test. If poly coombs is negative, well and good. If positive we perform IgG coombs test and send Complement coombs test to reference laboratory. We may have to send no more than ten times a year for complement coombs, but I don't have to keep anti-C3b,C3d and complement check cells.

[hmust1]

As always...the wealth of knowledge on this site has been extremely helpful!

We perform an extremely low volume of physician requested DATs. I was planning on continuing to test initially with Poly, then confirm positives with only IgG...allowing for the assumption that if the IgG is negative, complement is causing the Poly to be positive...and in our interpretation (hopefully our next inspector feels the same way)...satisfying the CAP checklist requirement for "detecting" complement.

Thank you everyone for the input!

Heather

[cmiller]

We were following the same line of testing for our DATs: Poly first, then if positive Anti-IgG. We assumed that if the poly was positive and the IgG negative it was complement.

We had our CAP inspection in February and that seemed good enought for them, but if you do this you must also keep the Complement check cells inorder to verify the reactivity of the complement component of the polyspecific reagent. We got dinged on this.

Because of this and the fact that ortho doesn't have complement check cells, I changed our DAT procedure.

We no longer use Polyspecific reagent. For DATs we test with Anti-IgG and Anti-C3b,C3d separately, and use separate check cells for each.

CAP seemed to be ok with this when I sent in our revised procedure/order request for complement reagents.

Bottom line, I believe it is ok to use only the Poly and IgG reagents as long as you use complement check cells to check the reactivity of the complement part of the poly.

[hmust1]

Candace,

CAP dinged you

The notes for TRM.40210 specifically refer you back to TRM.40200 for use of polyspecific antiglobulin. And TRM.40200 states that "When performing an antiglobulin test with anti-IgG OR polyspecific antiglobulin reagents, are IgG-coated red blood cells used in all negative antiglobulin tests?"

As a CAP inspector myself...I would think that TRM.42010 (and hence the Complement control cells) would be N/A if you're not using the anti-C3 reagent.

Did you challenge the inspector's citation with CAP during the inspection? or did you just submit corrective action afterwards?

Heather

[cmiller]

Well thats what I was thinking when I went through the checklist in preparation for the inspection, but our inspector didn't agree.

He used the line in the Note: "Tests found negative by tube methodology must be checked with the addition of appropriate check cells." His interpretation was that this included the complement component b/c it was stated after the statement about IgG coated cells for negative tests.

He also refered to the manufacturer's package insert which states "The positive control of anti-beta[complement] activity is a test with red cells sensitized with complement." This indicates that the complement component should also be controlled in the same manner as anti-IgG.

That was this inspectors take on it and we went with it - we wanted to change our procedure anyway...

I didn't call CAP to check on this, but it might be worth while to others with pending inspections.

Thanks for the reply Heather.

[noelrbrown]

You should always use an anti complement reagent for DAT on post transfusion samples. There is always the danger of a complement activating antibody that has sensitised the cells yet remains undetected and could cause a violent transfusion reaction if the patient's immune system is challenged again with the same antigen. Complement coated cells are not hard to make in the lab. using fresh plasma and can last up to a week in PBS and even longer in Alsevers.

[KBBB]

I'm going with BloodBanks' reply-thanks. Even though there are other opinions, based on my experience with inspections and this issue at other facilities I don't think it is considered valid to assume complement is coating the cells without directly testing for it. I don't want to get into producing complement check cells either.

Different inspectors have different opinions based on their training and expertise. The only way to stop the gray areas is to write the questions plain and simple. example...."If your lab is performing DAT's and reporting results for Complement-coated cells, you must use anti-C3b, C3d and verify the reagent performance by the use of complement-coated check cells" I'm sure you all have seen labs "get away" with something because the inspector didn't notice. You may think you have a valid argument until an expert at the CAP/Joint Commission corrects you. That's why inspections can be so stressful!!!!

[AMcCord]

Not to beat a dead horse, but....

TRM.40655 asks 'when a direct antiglobulin test is ordered...does the test system allow detection of RBC-bound complement as well as IgG'? Then TRM.40210 asks 'when performing an antiglobulin test with anti-C3 antiglobulin reagents are C3-coated cells used in all negative antiglobulin tests'? (I haven't seen my new check list yet, so I'm going on our last one and an inspection checklist we did this spring.)

When you are doing a DAT which has been ordered by a physician, it is for diagnostic purposes - you are seeking to detect not only IgG but complement as well. Complement coated red cells are significant for oncology patients (treatment and prognosis, as I understand it) and patients with anemia-cause under investigation, as well as CAS, certain drugs, etc. If you are not comtrolling the anti-C3 activity of your poly AHG, how can you be sure that a neg DAT is not a false neg for complement? (Have I ever seen AHG fail QC for either IgG or complement?... no, but I don't think CAP would buy that defense from me about reagent QC .)

When this whole complement QC thing first appeared on the checklist a few years back, the lab manager and I debated the requirement for C3 coated cells. I called CAP to get a ruling on that and was told that I did need to use C3 coated cells with poly AHG when doing DATs (ordered by physician) for diagnostic purposes. So, I don't think you can meet the intent of 40655 and 40210 w/o using C3 cells. Immucor sells them - they are on my standing order along with regular Check Cells. Yes, it is an extra expense. If you don't get many orders for DATs, your simple option might be to send out any ordered DATs and not have to worry about it. Any other AHG testing, do under a protocol you define to exclude detection of C3.

[hmust1]

Ok, ok... Just to redeem myself here...the idea of eliminating the anti-complement and complement check cells was SUGGESTED TO ME by our last CAP Blood Bank Inspector! Maybe I'm missing something...but using the POLY-specific reagent IS a method to detect bound complement, isn't it? Therefore, satisfying TRM.40655. And as I mentioned previously... TRM.40210 specifically refers you back to TRM.40200 if you're using POLY-specific reagents. HOWEVER...the polyspecific reagent package insert DOES indicate that it should be controlled with BOTH IgG AND Complement coated red cells...so you've got me there anyway!

No worries, our current procedures and reagents are all still in tact! I was merely investigating a POTENTIAL change to save costs.

And since we've opened this can of worms...doesn't any one else have problems actually getting those very expensive complement control cells to work (and will admit it)??

[AMcCord]

You are correct - poly AHG detects complement, fulfilling the requirement to detect C3. You just need to do the complement QC on the poly to prove it works for the C3 as well as the IgG.

As to the control cells for complement, Oh ya, I'll admit it! they can be a wee bit 'touchy'. About once a year we have to request a fresh shipment - if they come in during really really cold or really really hot weather, they sometimes don't work very well or don't work at all. Seems like some lots are better than others, too. It helps to have a really light touch when you shake them off.

I tell my MT students that it's a good test of their tube shaking talent if they can get a nice 2+.

Edited July 10, 2008 by AMcCord

[David Saikin]

We perform anti-Comp testing using buffered gel tubes. The diluted (0.8%) Immucor compl Check cells are always 3+-4+ using in this system. I hated those cells when using tubes; could barely get 1+ routinely.

[mda]

David, did you validate this procedure using the Gel buffered card for anti-C3b, -C3d testing? I know that Immucor complement Check Cells always works using the buffered gel. We tried to parallel test this before and did not worked. Some of our weak reaction in tube, failed to react (5 out of 7) in buffered gel method ( we even try to extend the incubation time at RT).

[David Saikin]

I did validate but with only a few positive specimens (3). I had asked our large referral institution for some, but they were unable to assist me. All my C+ tube DAT's validated in gel.

[marvy1]

If you only test with Poly and IgG, what happens when the Poly is pos and the IgG is pos? Do you assume it's only IgG? Why couldn't it be both IgG and C3? If you are worried about the cost of reagents, maybe try making your own complement-coated control cells using sucrose. We find that works fine and its cheap.

[Mary Leslie]

Are you doing pre and post DATs with transfusion reactions?

[Yanxia]

I think the problem to use poly and anti-IgG only is the component of poly and the concentration difference.

Dose it only contain anti-component and anti-IgG? What is the influence of the concentration difference to the result?

Sorry, I have not read all the posts before me because the time limit, if my post have some wrong, please point it out. Thanks!

[LaraT23]

We currently do our DAT's with poly only and all positives are sent out because I cannot afford to keep complement coated read cells for QC of the complement portion or for testing. I am of the mind to never assume anything, and always get both portions of the dat question answered.

[AMcCord]

How do you know that your poly is detecting C3 activity if you don't QC it with complement coated cells?