Kell antigen system
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2008-05-29T19:30:14Z
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{{Protein
|Name=Kell protein
|image=
|caption=
|Symbol=KEL
|AltSymbols=ECE3, CD238
|HGNCid=6308
|Chromosome=7
|Arm=q
|Band=33
|LocusSupplementaryData=
|ECnumber=
|OMIM=110900
|EntrezGene=3792
|RefSeq=NM_000420
|UniProt=P23276
|PDB=
}}
The '''Kell antigen system''' (also known as '''Kell-Cellano system''') is a group of [[antigen]]s on the human red blood cell surface which are important determinants of [[blood type]] and are targets for [[autoimmune disease|autoimmune]] or [[alloimmunity|alloimmune]] diseases which destroy red blood cells. The Kell antigens are [[peptides]] found within the '''kell protein''', a 93 [[kilodalton]] transmembrane [[zinc]]-dependent endopeptidase which is responsible for cleaving [[endothelin-3]].<ref name="pmid7849312">{{cite journal | author = Lee S, Wu X, Reid M, Zelinski T, Redman C | title = Molecular basis of the Kell (K1) phenotype | journal = Blood | volume = 85 | issue = 4 | pages = 912–6 | year = 1995 | pmid = 7849312 | doi = | issn = | url = http://bloodjournal.hematologylibrary.org/cgi/content/abstract/bloodjournal;85/4/912 }}</ref><ref name="pmid10438732">{{cite journal | author = Lee S, Lin M, Mele A, Cao Y, Farmar J, Russo D, Redman C | title = Proteolytic processing of big endothelin-3 by the kell blood group protein | journal = Blood | volume = 94 | issue = 4 | pages = 1440–50 | year = 1999 | pmid = 10438732 | doi = | issn = | url = http://bloodjournal.hematologylibrary.org/cgi/content/abstract/bloodjournal;94/4/1440 }}</ref>
There are several [[allele]]s of the [[gene]] which creates Kell protein. Two such alleles, ''K<sub>1</sub>'' (Kell) and ''K<sub>2</sub>'' (Cellano), are the most common. The kell protein is tightly bound to a second protein, [[XK (protein)|XK]], by a [[disulfide bond]]. Absence of the XK protein (such as through [[genetic deletion]]), leads to marked reduction of the Kell antigens on the red blood cell surface. Absence of the Kell protein (K<sub>0</sub>), however, does not affect the XK protein.<ref name="pmid11134029">{{cite journal | author = Yu LC, Twu YC, Chang CY, Lin M | title = Molecular basis of the Kell-null phenotype: a mutation at the splice site of human KEL gene abolishes the expression of Kell blood group antigens | journal = J. Biol. Chem. | volume = 276 | issue = 13 | pages = 10247–52 | year = 2001 | pmid = 11134029 | doi = 10.1074/jbc.M009879200 | issn = }}</ref>
The Kell protein has also recently been designated '''CD238''' ([[cluster of differentiation]] 238).
== Disease association ==
Kell antigens are important in [[transfusion medicine]], [[autoimmune hemolytic anemia]], and [[hemolytic disease of the newborn]]. Individuals lacking a specific Kell antigen may develop [[antibody|antibodies]] against Kell antigens when transfused with blood containing that antigen. Subsequent blood transfusions may be marked by destruction of the new cells by these antibodies, a process known as [[hemolysis]]. People without Kell antigens(K<sub>0</sub>), must be transfused with blood from donors who are also K<sub>0</sub> to prevent hemolysis.
[[Autoimmune hemolytic anemia]] (AIHA) occurs when the body produces an antibody against a blood group antigen on its own red blood cells. The antibodies lead to destruction of the red blood cells with resulting [[anemia]]. Similarly, a pregnant woman may develop antibodies against fetal red blood cells, resulting in destruction, anemia, and [[hydrops fetalis]] in a process known as [[Hemolytic disease of the newborn (anti-Kell)|hemolytic disease of the newborn]] (HDN). Both AIHA and HDN may be severe when caused by anti-Kell antibodies,<ref name="pmid8623782">{{cite journal | author = Weiner CP, Widness JA | title = Decreased fetal erythropoiesis and hemolysis in Kell hemolytic anemia | journal = Am. J. Obstet. Gynecol. | volume = 174 | issue = 2 | pages = 547–51 | year = 1996 | pmid = 8623782 | doi = | issn = }}</ref> as they are the most immunogenic antigens after those of the [[ABO blood group system|ABO]] and [[Rhesus blood group system]]s.
==McLeod phenotype==
{{main|McLeod syndrome}}
McLeod phenotype (or McLeod syndrome) is an [[X-linked]] anomaly of the Kell blood group system in which Kell antigens are poorly detected by laboratory tests. The McLeod gene encodes the XK protein, a protein with structural characteristics of a membrane transport protein but an unknown function. The XK appears to be required for proper synthesis or presentation of the Kell antigens on the red blood cell surface.
==History==
The Kell group was named after the first patient described with antibodies to K<sub>1</sub>, a pregnant woman named Mrs. Kellacher in 1945.<ref>Coombs RRA, Mourant AE, Race RR. ''A new test for the detection of weak and incomplete Rh agglutinins.'' Br J Exp Pathol 1945;26:255</ref> Mrs. Cellano was likewise a pregnant woman with the first described antibodies to K<sub>2</sub>. The K<sub>0</sub> [[phenotype]] was first described in 1957 and the McLeod phenotype was found in Hugh McLeod, a [[Harvard]] dental student, in 1961.<ref name="pmid13477267">{{cite journal | author = Chown B, Lewis M, Kaita K | title = A new Kell blood-group phenotype | journal = Nature | volume = 180 | issue = 4588 | pages = 711 | year = 1957 | pmid = 13477267 | doi = | issn = }}</ref><ref name="pmid13860532">{{cite journal | author = Allen FH Jr, Krabbe SM, Corcoran PA | title = A new phenotype (McLeod) in the Kell blood-group system | journal = Vox Sang. | volume = 6 | issue = | pages = 555–60 | year = 1961 | pmid = 13860532 | doi = | issn = }}</ref>
== Other associations ==
Evidence supports a genetic link between the Kell blood group (on [[chromosome 7]] q33) and the ability to taste [[phenylthiocarbamide]], or PTC, a bitter-tasting [[thiourea]] compound.<ref name="pmid4435792">{{cite journal | author = Crandall BF, Spence MA | title = Linkage relations of the phenylthiocarbamide locus (PTC) | journal = Hum. Hered. | volume = 24 | issue = 3 | pages = 247–52 | year = 1974 | pmid = 4435792 | doi = | issn = }}</ref><ref name="pmid976995">{{cite journal | author = Conneally PM, Dumont-Driscoll M, Huntzinger RS, Nance WE, Jackson CE | title = Linkage relations of the loci for Kell and phenylthiocarbamide taste sensitivity | journal = Hum. Hered. | volume = 26 | issue = 4 | pages = 267–71 | year = 1976 | pmid = 976995 | doi = | issn = }}</ref> Bitter taste receptor proteins in the taste buds of the tongue that recognise PTC are encoded on nearby chromosome [[Locus (genetics)|locus]] 7 q35-6.
== References ==
{{Reflist|2}}
== External links ==
*{{OMIM|110900}} - OMIM entry for Kell protein
*{{OMIM|314850}} - OMIM entry for XK protein
* [http://www.ncbi.nlm.nih.gov/projects/mhc/xslcgi.fcgi?cmd=bgmut/systems_info&system=kell Kell at BGMUT] Blood Group Antigen Gene Mutation Database at [[NCBI]], [[NIH]]
* {{MeshName|KEL+protein,+human}}
{{Clusters of differentiation}}
{{transfusion medicine}}
[[Category:Clusters of differentiation]]
[[Category:Transfusion medicine]]
[[Category:Hematology]]
[[Category:Blood antigen systems]]
[[lt:Kell antigenas]]