GinaL

I just answered this question.


My Score PASS  

I just answered this question.


My Score PASS  

I just answered this question.


My Score PASS  

Both ficin and papain work well for adsorptions. We have routinely used ficin in our reference lab for decades, both for antibody ID and adsorptions. And both enzymes can be used as constituents of ZZAP. A couple of years ago I compared cysteine-activated papain and ficin as constituents of ZZAP, and the volume of 1%ficin used in ZZAP. In the AABB Technical Manual, the ZZAP recipe calls for twice as much 1% ficin as 1% papain without explanation. I found there is no need to use 2x the volume of ficin. I suspect there may have been some issues with the activity of ficin some years ago. We prepare and standardize our enzymes. Both the ficin and papain for this study were purchased from Sigman-Aldrich.  ref: Leger & Garratty. Comparison of papaina and ficin as constituents of ZZAP for adsorption using allogeneic RBCs to remove warm autoantibodies for detection of alloantibodies (abstract). Transfusion 2011;51(Suppl):173A. 
 
Gina Leger

Drug-induced immnune hemolytic anemia is uncommon, but piperacillin is now the top contender of all the drug antibody investigations we perform in Dr. George Garratty's research lab at the American Red Cross, Southern California Region. Ceftriaxone and cefotetan are also high on our list. Piperacillin, although it is a semi-synthetic penicillin is unlike penicillin G in both the clinical presentation and in the serology. Piperacillin is often given in combination with tazobactam, a beta lactamase inhibitor, and is commonly given to patients with cystic fibrosis for lung infections. Patients who develop anti-piperacillin often have prior exposure to the drug. Also unlike with penicillin, intravascular hemolysis can be seen and the hemoglobin can drop dramatically. Fatalities have been reported. Unfortunately, we cannot predict which patients will or will not develop anti-piperacillin. Monitoring the hemobglobin is the best initial indicator, then following up with the other typical indicators of hemolysis (indirect bili, LDH, haptoglobin, evaluating peripheral blood smear). A direct antiglobulin test should then follow suspected hemolysis to determine if it is immune-mediated.
A significant finding with piperacillin antibodies is that while the patient is still receiving the drug (it is intravenous), the serology can mimic warm autoantibodies, and often with anti-e specificity. One-to two days after the drug is stopped, however, this plasma reactivity disappears. We believe this reactivity is caused by circulating drug (i.e., no in vitro drug is needed). And to baffle this serologist, we have even seen reactive eluates is some patients with this phenomenom. We have even seen some patients who have mistakenly been treated for warm autoimmune hemolytic anemia (e.g. with steroids) based primarily on the serology. Once the drug is stopped the hemolysis subsides.
Testing for antibodies to piperacillin is performed by adding a solution of the drug to serum and untreated RBCs (we also test enzyme-treated RBCs). Piperacillin does bind readily to RBCs so testing can be performed with piperacillin-treated RBCs, but we have found that plasma from blood donors and random patients can directly agglutinate piperacillin-treated RBCs, so we do not recommend this method in order to avoid misinterpretation (false positive result). Piperacillin antibodies do not have high titers so testing a dilution of the serum to get around this problem is not advised.
So, in addition to a dropping hemoglobin, a serologic clue is a new warm autoantibody in a patient whose initial clinical presentation is not warm autoimmune hemolytic anemia! If the eluate is reactive, it may react weaker than the plasma.
Gina Leger