revbrashematolhemoter.2017;39(1):91–92
w w w . r b h h . o r g
Revista
Brasileira
de
Hematologia
e
Hemoterapia
Brazilian
Journal
of
Hematology
and
Hemotherapy
Letter
to
the
Editor
Red
cell
autoantibody
mimicking
anti-C
specificity:
a
rare
manifestation
DearEditor,
Theassociationofsystemiclupuserythematosus(SLE)with
autoimmune hemolytic anemia (AIHA) is a known
phe-nomenon.InmanycasesofAIHA,noautoantibodyspecificity ispresent.Thepatient’sserumreactswithalloftheredblood cell (RBC)samples testedand the autoantibody appearsto havebroadspecificityintheRhbloodgroupsystem. Occasion-ally,RBCautoantibodiesdemonstrateapparentspecificityfor simpleRhantigensbutautoantibodiestoWrb,Kpb,Jka,and Uantigenshavealsobeenreported.1,2Weherebyreportarare
exampleofanautoantibodymimickinganti-Cspecificityina patientwithlupusnephritis.
Case
description
A 26-year-old lady was admitted to our tertiary care cen-ter with a three-week history of pedal edema. She also had a two-week priorhistory ofstill birth(at 32 weeksof gestation). At the time ofadmission, she was not on any medication. There was no previous history of transfusion. Thepatientwashemodynamicallystable.Thecompleteblood countrevealed hemoglobin: 7.5g/dL,total leukocyte count: 16.4×103/Landplateletcount:142×109/L.RBCindiceswere asfollows:meancorpuscularvolume(MCV)=119.8fL,mean corpuscularhemoglobin(MCH)=97.0pg,andmean corpuscu-larhemoglobinconcentration (MCHC)=81.0g/dL.Peripheral smearrevealednormocyticnormochromicanemiawith occa-sionalnucleatedRBCs.Thecorrectedreticulocytecountwas 3.4%. However, no spherocytes were evident. Other perti-nentinvestigationswereasfollows:totalbilirubin−indirect fraction=7.2mg/dLanddirectfraction=1.2mg/dL,low com-plement C3=58.5mg/dL (normal range: 90–180mg/dL), low complement C4=9mg/dL(normal range: 10–40mg/dL), ele-vatedlactatedehydrogenase(LDH)=1226U/L(normalrange: up to 225U/L), creatinine=0.7mg/dL (range: 0.7–1.2mg/dL) andalbumin=1.2mg/dL(range:3.4–5.2mg/dL).Renalbiopsy wasperformedandthediagnosiswasconsistentwithlupus nephritis–ClassV.
We received a request for blood grouping and a direct antiglobulintest(DAT).Onvisualinspection,theplasmaand serum revealed evidenceofhemolysis.Bloodgrouping was BRhDpositive.DAT waspositiveforimmunoglobulinG(3+) andC3d(2+)incolumnagglutinationtechnology(CAT)using monospecific Coombs’ reagent (Biorad, Switzerland). RBC antibodyscreeningwaspositive(3+)inanindirect antiglobu-lintest(IAT)phaseusingacommercial3-cellpanel(ID-Diacell I-II-III,Biorad,Switzerland)withapositiveautocontrol.RBC antibodyidentification wasachievedwithacommercial 11-cellidentificationpanel(IDDiaPanel,Biorad,Switzerland)in IATphase.Theantibodywasidentifiedasanti-Casitreacted (3+gradeofagglutination)withallC-positivecellsandshowed noreactionwithallC-negativecells.Antibodieselutedfrom the patient’s RBCs using an acid elution kit (Diacidel, Bio-rad, Switzerland) exhibited anti-C specificity. Heat elution (carriedoutat56◦Cfor10min)ofthepatient’sRBCswas per-formedand extendedRh antigenphenotypingoftheRBCs was attained usingmonoclonal antibodies inCAT(Diaclon Rh-Subgroups+K,Biorad,Switzerland).HerRhantigen phen-otypingwasC+,c−,E−,e+.ThepresumedRhhaplotypewas DCe/DCe(R1R1).Rhgenotypingfacilitiesarenotavailableat ourcenter.
Adsorption of the serum was done based on the tech-niquedescribedbyIssitetal.3Anequalvolumeofpatient’s
serum andpapaintreatedpackedRBCs (DCe/DCe,R1R1and dce/dce,rrRBCs)weremixedandincubatedat37◦Cforone hour.Aftersingleadsorption,theadsorbedserumwastested forthepresenceofanti-CusinganRBC antibodyscreening panel.Antibodieswerecompletelyadsorbedfromtheserum with C-negativeaswell as C-positive cells.Themimicking specificitywasconfirmedby:(1)antibodyreactivitywas con-sistent with anti-C, (2) patient’s RBCs were positive for C antigen and (3) adsorbed serum did not retain the anti-C activity. The presenceof underlyingantibodies was tested based on the dilution technique described by Jang et al.4
92
revbrashematolhemoter.2 0 1 7;39(1):91–92identificationpanel(IDDiaPanel,Biorad,Switzerland). Alloan-tibodieswerenotdetected.OneunitofBRhD+CnegativeKell
negativepackedRBCswascrossmatchedforthispatientand foundcompatible,althoughshedidnotrequireatransfusion duringthisadmission.Initially,thepatientwasadministered apulsedoseofintravenousmethylprednisolonewhichwas latertaperedtooralprednisolone.Overaperiodofoneweek, thepatient’sconditionimprovedgraduallyandshewas dis-charged.Thepatientatpresentisbeingfollowed-upregularly.
Discussion
InmostpatientswithwarmAIHA,RBCautoantibodiesreact with all RBCs (pan-reactive). Infrequently, these autoanti-bodies dohaveapparent specificity(patient’s RBCs may or may not contain the antigen) which disappears following adsorptionwithantigennegativecells.Thisconceptwasfirst describedbyFudenbergas“wrongantibodies”;thesearesaid tobeantibodieswithmimickingspecificity,usuallydirected againstRhantigens(e,Eandc),althoughtheirtruespecificity ismostlyanti-Hroranti-Hr0.5 However,apparentanti-C in
Africandescendantsmaybeanti-Rh31oranti-Rh34.2
Auto-antibodiesmayalsomimicthespecificitiesofanti-K,anti-Jka andanti-Kpb.5Todate,onlylittleisknownaboutthe
autoanti-bodieswithmimickingspecificityinpatientswithwarmAIHA. Theirfrequencyisreportedtorangefrom12%to27%.4
How-ever,theirexactprevalenceinourpatientpopulationisnot known.Tothebestofourknowledge,thereareno unequivo-calreportsofautoantibodieswithmimickingspecificityfrom theIndiansubcontinent.
Multiplemechanismshavebeenproposedfortheir occur-rence. Autoantibodies with mimicking specificity can be inducedbydrugssuchasalpha-methyldopaorautoantibodies unfolding to alloantibodies at a later stage.6 Occasionally,
autoantibodies (anti-D, -C and -e) mimic alloantibodies, wherein thepatient’s RBCs show markeddepression ofRh antigenexpressionduring thehemolytic episode. Antibod-iescan beeluted fromRBCs despiteanegativeDAT.1,2 The
reasonfortheoccurrenceofsuchantibodiesinourpatient could not beestablished. In patients with warm autoanti-bodies, the presence of alloantibodies can be detected by adsorption techniques using ZZAP (a mixture of 0.1mol/L dithiothreitol plus 0.1% cysteine-activated papain or 0.1% ficin),PEG(Polyethyleneglycol)orbydilutingpatient’sserum. The dilution technique of patient’s serum is found to be a good alternative to ZZAP or PEG adsorption for detec-tingunderlyingalloantibodiesinpatientswithautoantibodies withmimickingspecificitybecausetheadsorptiontechniques aretime-consumingandsuchfacilitiesmaynotbeavailable inall centers.4 Antibodies withmimicking specificity have
been reported tocause clinically significant hemolysis.6 In
contrast,Jangetal.suggestedthattheseantibodies donot resultinhemolytictransfusionreactionswhensuchpatients aretransfusedwith“leastincompatibleunits”.4Ourpatient
hadevidenceofhemolysisatthetimeofadmission,probably mediatedbyautoantibodies.Patientshavingautoantibodies withmimickingspecificityintheirserumshouldbetransfused withantigennegativeunits.
Toconclude,autoantibodieswithmimickingspecificityare rarelyencounteredintheroutinepractice.Theyareconfirmed byadsorptionofpatient’sserumwithantigen-negativeRBCs. Dilutionofthepatient’sserumcanbeusedasanalternative toexhaustivetechniquessuchasZZAPadsorptiontoidentify theunderlyingalloantibodiesinpatientswithwarm autoan-tibodiesespeciallywhenthefacilitiestoperformadsorptions are notavailable.However,itshouldbeborneinmindthat only the alloantibodies whose titer is higher than that of the autoantibodies’titerwillbedetected.Giventheclinical implication,greateremphasisshouldbepaidonestablishing anaccuraterapiddiagnosisandtransfusingantigen-negative RBCunits.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
r
e
f
e
r
e
n
c
e
s
1.FungMK.Technicalmanual.18thed.Bethesda:American AssociationofBloodBanks;2014,435pp.
2.PetzLD,GarrattyG.Immunehemolyticanemias.2nded. Philadelphia,PA:ChurchillLivingstone;2004.p.231–42.
3.IssittPD,CombsMR,BumgarnerDJ,AllenJ,KirklandA, Melroy-CarawanH.Studiesofantibodiesintheseraof patientswhohavemaderedcellautoantibodies.Transfusion. 1996;36(6):481–6.
4.JangM-J,ChoD,ParkK-U,YazerMH,ShinM-G,ShinJ-H,etal. Autoantibodieswithmimickingspecificitydetectedbythe dilutiontechniqueinpatientswithwarmautoantibodies.Ann LabMed.2013;33(5):343–8.
5.IssittPD,PavoneBG.Criticalre-examinationofthespecificity ofauto-anti-Rhantibodiesinpatientswithapositivedirect antiglobulintest.BrJHaematol.1978;38(1):63–74.
6.DwyreDM,ClapperA,HeintzM,ElbertC,StraussRG.Ared bloodcellautoantibodywithmimickinganti-Especificity. Transfusion.2004;44(9):1287–92.
RajeswariSubramaniyan∗, MangalakumarVeerasamy
KovaiMedicalCenterandHospital,Coimbatore,India
∗Correspondingauthorat:DepartmentofTransfusionMedicine, KovaiMedicalCenterandHospital,AvinashiRoad,Coimbatore 641014,India.
E-mailaddress:arthisoundarya@gmail.com
(R.Subramaniyan).
Received20August2016 Accepted22November2016 Availableonline23December2016
1516-8484/
©2016Associac¸ ˜aoBrasileiradeHematologia,Hemoterapiae TerapiaCelular.PublishedbyElsevierEditoraLtda.Thisisan openaccessarticleundertheCCBY-NC-NDlicense(http:// creativecommons.org/licenses/by-nc-nd/4.0/).
