Rev. Bras. Hematol. Hemoter. vol.39 número4

rev bras hematol hemoter. 2017;39(4):293–294

w w w . r b h h . o r g

Revista

Brasileira

de

Hematologia

e

Hemoterapia

Brazilian

Journal

of

Hematology

and

Hemotherapy

Scientific

Comment

Kidd

system

antigens

and

kidney

disease

夽

Melca

Maria

Oliveira

Barros

UniversidadeFederaldeSãoPaulo(Unifesp),SãoPaulo,SP,Brazil

TheKidd blood group system(ISBT009), identified in1951,

wastheninth bloodgroup systemandit isconsideredthe

ninthmostclinicallyimportant.AntigensoftheKiddblood

group system are expressed on type 3 glycoproteins, also

known as the urea transporter B(UT-B). The JK protein is

expressedonredbloodcells(RBCs)andintheendotheliumof

thedescendingvasarectaandepithelialsurfacesoftherenal

innermedulla.1 _{Evidenceofthefunctionofthe Kiddblood}

groupsystemfirstcametolightfromtheobservationin1982

thatJk(a-b-)RBCswereresistanttolysisin2Mureain

con-trasttoRBCswithnormalKiddantigens.RBCshavingnormal

JKphenotypeswilllysewithin30sastheureaistransported

into the cells,followed bya rapidosmoticinflux ofwater.

Becauseofthelackofureatransportandthereforenowater

uptake,Jk(a-b-)cellsremainintactaftertwominutes,which

demonstratestheroleoftheJKproteininfacilitatingrapid

ureatransportacrosstheRBCmembrane.2_Themajor

physio-logicroleforureatransportersisintheurinaryconcentrating

mechanism.However,noclinicalsequelawasfoundintwo

patientswiththeJknullphenotypesuggestingthepresence

ofcompensatorymechanisms.3

ThepaperbyCapriolietal.4_{publishedinthisissueofthe}

RevistaBrasileiradeHematologiaeHemoterapiainvestigates

pos-sible relationsbetween the absence ofJka or Jkb antigens

inpatientswithchronic kidney disease.Thisisinteresting

becauseindividualswiththeJk(a-b-) phenotypehad lower

urine-concentratingability,howeverifpatientswithchronic

kidneydiseasepresentsomedifferenceintheKiddphenotype,

thedistributionremainsunknown.Moreover,thelocationof

the JK antigens on renal cells raises fascinating questions

DOIoforiginalarticle:http://dx.doi.org/10.1016/j.bjhh.2017.05.007.

夽

SeepaperbyCapriolietal.onpages301–5.

∗ _{Correspondenceto:DepartamentodeMedicina,DisciplinadeHematologia,UniversidadeFederaldeSãoPaulo(Unifesp),RuaDiogode}

Farias,VilaClementino,04023-900SãoPaulo,SP,Brazil.

E-mailaddress:[email protected]

about the impact of the Kidd system antigens on kidney

disease.

Capriolietal.,4_{foundnodifferenceinphenotype}

frequen-cies orthe distribution ofJka and Jkbantigenswhen they

comparedpatientswithchronickidneydiseaseandcontrols,

howeverthenullphenotypewasnotobservedinthegroups.

ThissuggeststhattheabsenceofJkaorJkbdoesnotinfluence

thedevelopmentofchronickidneydiseaseinthesechronic

kidneydiseasepatients,althoughtheinfluenceoftheabsence

ofbothhasnotbeenstudied.Severalcasereportssuggesta

roleoftheKiddSystemonrenalgraftsurvivalinkidney

trans-plants. Lerutet al.5 _{demonstratedinaretrospective cohort}

studyof370kidneytransplantsthatmismatchofthe

recipi-ent/graftattheJKlocuswasassociatedwithmoreinterstitial

inflammationthanwhentheywerematchedasobservedat

biopsyofthetransplantedkidney,althoughoverallgraft

sur-vivalwasnotinfluenced.

TheauthorssuggestthatintheabsenceofUT-B,another

transporter,suchasUT-A,wouldnotallowureatoaccumulate

intherenalmedulla,therebyprotectingagainstrenal

dysfunc-tion,howevernofunctionalexperimentswereperformedto

affirmthis conclusion.Finally, whilethefunctionofthe JK

proteinisknown,futurestudieswouldbeexpectedtoresult

inamorecompleteunderstandingabouttheimpactofKidd

systemantigensonkidneydisease.

Conflicts

of

interest

Theauthordeclaresnoconflictsofinterest.

http://dx.doi.org/10.1016/j.bjhh.2017.07.004

1516-8484/©2017PublishedbyElsevierEditoraLtda.onbehalfofAssociac¸ ˜aoBrasileiradeHematologia,HemoterapiaeTerapiaCelular.

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1.HamiltonJR.Kiddbloodgroupsystem:areview. Immunohematology.2015;31(1):29–35.

2.HeatonDC,McLoughlinK.Jk(a-b-)redbloodcellsresisturea lysis.Transfusion.1982;22(1):70–1.

3.SandsJM,GargusJJ,FröhlichO,GunnRB,KokkoJP.Urinary concentratingabilityinpatientswithJk(a-b-)bloodtypewho lackcarrier-mediatedureatransport.JAmSocNephrol. 1992;2(12):1689–96.

4.CaprioliTV,VisentainerJ,SellAM.Lackofassociationbetween Kiddbloodgroupsystemandchronickidneydisease.RevBras HematolHemoter.2017;39(4):301–5.