From: Guidelines for Antibody Identifcation, American Association of Blood Banks, 2010. Additional Guidance and Testing, page 21

 

"2. Exclusion of anti-E and anti-C may be completely eliminated for patient with anti-c and anti-e, respectively, because of the paucity of c-E+ and e-C+ donor units. Policies do differ in this regard.

 

    a. In addition to selecting donor units lacking the antigen(s) corresponding to the known antibody(ies), select donor units lacking the antigen(s) for which antibody exclusion has not been performed.  For example, select c-E- units with anti-c and C-e- units with anti-e, even though c-E+ or C+e- red cells were not tested and the presence or absence of anti-E or anti-C, respectively, is unknown.

 

    b.  Select donor units lacking the antigen(s) corresonding to the known antibody(ies).  When transfusion is requested, an antiglobulin crossmatch of the appropriate antigen-negative donor cells will be required (ie, c- or e- units would be crossmatched).  If the patient also had anti-E or anti-C, not excluded by antibody identification testing, antigen-positive donor unit would be incompatible."

 

 

Which policy do you follow, A or B?  ( assume,  that in either case, antiglobulin crossmatch is done.)

 

Thanks,

 

Dan

 

 

If we have a patient with an anti-c or anti-E we antigen type them for both c and E. If for example they have anti-c, but have the E antigen then we wouldn't worry about it. If they're negative for E and we can rule it out then we don't worry about it; if we can't rule it out then we would give c-E- units.

In the UK, the National External Quality Assurance Scheme (NEQAS) does not require that either anti-E be excluded in the case of an anti-c or anti-C be excluded in the case of an anti-e, but would expect either c- E- or C- e- blood to be cross-matched in such cases.

The reason for this is two-fold.

Firstly, R1Rz and R2Rz red cells (and RzRz, come to that) are very rare, and most hospital laboratories would not have access to such cells.

Secondly, in the case of anti-e, it is not necessarily easy to exclude a pure anti-C anyway, because most apparent sera containing anti-C (anti-Rh2) actually contain a mixture of anti-C and anti-Ce (anti-Rh7), with the anti-Ce being the major part of the mixture.

The reason why we would not go for cross-match compatible blood that has not been tested and found to be negative for the E or C antigens respectively, is because cross-matching is unreliable in detecting the presence of these antibodies. The screening red cells and the antibody identification red cells are selected to express these antigens maximally, and are in a medium that will preserve antigenicity (rather than the ability to carry and exchange oxygen), whereas the red cells in a unit are, of course, random in terms of the expression of antigenicity, and are in a medium that is designed to preserve the oxygen carrying capacity and exchange (rather than preserving maximal antigen expression).

All that having been said, working, as I do, in a Reference Laboratory, we do go the extra mile and exclude the presence of either an anti-E or an anti-C, but it is actually a matter of professional pride, rather than a necessity!

We do B

I also want to know to know if there is a anti-E hiding in there behind the anti-c. We usually have a RZR1 cell on one of our panels, or can beg a drop from our reference lab, conveniently located just a few miles away. What you say makes sense Malcolm, but are you aware of any studies done to demonstrate that phenomenon, titering anti-E against reagent and donor cells? Maybe it'll be my project after I finish my transplanted poop study for Anna...........

We do as Malcolm indicates, above, for the same reason.  For example,if we have a patient with anti-E, and negative for little-c, we would give them E and little c negative blood, even if they do not show anti-c.  It is really not necessary to do extra screening for the E antigen in the reverse case.  Likewise with ant-e/C.

 

Scott

I also want to know to know if there is a anti-E hiding in there behind the anti-c. We usually have a RZR1 cell on one of our panels, or can beg a drop from our reference lab, conveniently located just a few miles away. What you say makes sense Malcolm, but are you aware of any studies done to demonstrate that phenomenon, titering anti-E against reagent and donor cells? Maybe it'll be my project after I finish my transplanted poop study for Anna...........

I do know that there was a theory put about some years ago that anti-cE caused more severe HDFN than does a mixture of anti-c (monospecific) and anti-E (monospecific) and, as a result, we have been titrating samples from pregnant ladies with anti-c+E with various red cells to represent the three different specificities for some years now. Apart from proving that it gives my staff arm ache and costs more in terms of reagent red cells, I have seen no proof whatsoever that the theory holds true!

All,

 

What do you report on a CAP survey, when anti-c is identified in a sample that you can't rule-in or rule-out anti-E?

If we have a patient with an anti-c or anti-E we antigen type them for both c and E. If for example they have anti-c, but have the E antigen then we wouldn't worry about it. If they're negative for E and we can rule it out then we don't worry about it; if we can't rule it out then we would give c-E- units.

Ditto

Sometime we try to adsorb anti-c and with c+E- cells and then test is again to see if anti-E is present.

We usually have an RzR1 cell on a panel that we can use to rule out anti-E in the presence of anti-c but we don't have RzR2 cells so we just give C neg units to our patient who has anti-e because (a) we can't rule out anti-C and ( it is really easy once you have e neg units because they are always C neg too.

1) Why Eagle Eye?

2) Not ALWAYS Mabel! Overwhelmingly often - but not always!

1) Why Eagle Eye?2) Not ALWAYS Mabel! Overwhelmingly often - but not always!

1) I do not know . For academic purpose.

2) if we rule out anti-E no need to give E-

3) For survey we try to rule out

1) Thought so (and there is NOTHING wrong with that).

2) If you rule out anti-E, there is no need to give E-, if the patient is E+, but, on the other hand, if they are E-, and you give E+ blood, you are going to have to go through the entire process of doing the adsorption studies each and every time you see the patient from then onwards, in case they then produce an anti-E!

3) Understood.

If we have a patient with an anti-c or anti-E we antigen type them for both c and E. If for example they have anti-c, but have the E antigen then we wouldn't worry about it. If they're negative for E and we can rule it out then we don't worry about it; if we can't rule it out then we would give c-E- units.

Us, too.

When you have a E, c antigen negative patient and they are making only anti-E, I can see screening donor units for both E and c, as since the patient has been known to have been exposed to E, they have almost certainly been exposed to c. And if they are c antigen negative, giving them c positive blood (which is quite common) will cause them to start producing anti-c. (likewise for C/e)

But I do not see why they reverse should be true: needing E negative blood when the patient only produces anti-c? A person who is exposed to c antigen is much less likely to have been exposed to E, and the E antigen is relatively rare on donor cells (other antigens like Fya are much more common - no-one screens for those routinely either!)

I may be mistaken here, but I believe one can look at the AABB manual and see the same argument.

Scott

Ah, but the E antigen is more immunogenic than the Fy(a) antigen.

Ya.

Still... if we wanted to be really careful, we would completely phenotype for every significant antigen for both the patient and donor units. And I think that is where we are headed when we screen for E with anti-c patients, or for e with anti-C patients.

(In general, I think we are already enough anal-retentive!)

Scott

We screen the pt for their antigens and decide based on that. If they have Anti-E or Anti-c and are also E and/or c negative - they get R1R1 units. If they have Anti-C or Anti-e and are also C and/or e negative - they get R2R2 blood. This is the only prophylactic screening we do, but it works well based on the frequency of exposure to the opposite antigens that would occur if you ignored it. (Little c at 70%+ when you screen only for E, and Little e at 98% when you screen only for C). Issit and the AABB Manual seem to be split on the subject, so we went with careful. We see so many Anti-Es that we keep some R1R1 units around all the time for use on these pts. Our blood distributor gets the R2R2 units very efficiently, so we just order those at need.

Right, Malcolm.  That is why we still antigen type the e neg units for C.  Always in the sense that it "always" rains when you plan a picnic, not mathematically precise always.

Carolyn,

Are the units you get from your supplier labeled as R1R1 units? We don't get anything like that, but we do get a historical database than we can use to select units to antigen type.

Carolyn,

Are the units you get from your supplier labeled as R1R1 units? We don't get anything like that, but we do get a historical database than we can use to select units to antigen type.

 

Yes - when we order special screened units from our distributor - UBS, El Paso, they screen and label the units. There is extra charging for this service. We rescreen the units here, but it is much faster than searching our own inventory - especially since our distributor is doing a lot of prescreening now and many of the antigen negative units are already gone. They hold them in stock at the center and have a very fast response time for antigen negative unit requests.

Edited February 21, 201411 yr by carolyn swickard

In the UK, all units are typed for C, E, c, e and K, in addition the ABO and D.

These is true for special order from blood center or entire inventory is screened for those antigen malcolm

Entire inventory Eagle Eye.