The Kell antigen system (also called Kell–Cellano system) is a human blood group system, that’s, group of antigens on the human crimson blood cell floor that are essential determinants of blood sort and are targets for autoimmune or alloimmune illnesses which destroy crimson blood cells. The Kell antigens are K, k, Kpa, Kpb, Jsa and Jsb.[1] The Kell antigens are peptides discovered inside the Kell protein, a 93-kilodalton transmembrane zinc-dependent endopeptidase which is liable for cleaving endothelin-3.[2][3]
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Protein[edit]
The KEL gene encodes a kind II transmembrane glycoprotein[4] that’s the extremely polymorphic Kell blood group antigen. The Kell glycoprotein hyperlinks by way of a single disulfide bond to the XK membrane protein[5] that carries the Kx antigen. The encoded protein incorporates sequence and structural similarity to members of the neprilysin (M13) household of zinc endopeptidases.[6]
There are a number of alleles of the gene which creates Kell protein. Two such alleles, K1 (Kell) and K2 (Cellano), are the most typical. The kell protein is tightly sure to a second protein, XK, by a disulfide bond. Absence of the XK protein (resembling by means of genetic deletion or by means of a single level mutation inside the coding area of the XK gene[7]), results in marked discount of the Kell antigens on the crimson blood cell floor. Absence of the Kell protein (K0), nonetheless, doesn’t have an effect on the XK protein.[8]
The Kell protein has additionally lately been designated CD238 (cluster of differentiation 238).
Illness affiliation[edit]
Kell antigens are essential in transfusion medication, autoimmune hemolytic anemia and hemolytic illness of the new child (anti-Kell). Anti-K is the subsequent most typical immune crimson cell antibody after these within the ABO and Rh system. Anti-K sometimes presents as IgG class alloantibody. People missing a selected Kell antigen might develop antibodies towards Kell antigens when transfused with blood containing that antigen. That is significantly true for the “K” antigen which exhibits a comparatively excessive antigenicity and reasonably low frequency (~9%) in Caucasian populations. Anti-K can even happen following transplacental hemorrhage (TPH) related to childbirth making Kell an essential concern for hemolytic illness of the new child. Following the formation of anti-K, subsequent blood transfusions could also be marked by destruction of the brand new cells by these antibodies, a course of often known as hemolysis. Anti-K doesn’t bind complement, subsequently hemolysis is extravascular. People with out K antigens(K0) who’ve shaped an antibody to a K antigen, have to be transfused with blood from donors who’re additionally K0 to stop hemolysis.
Autoimmune hemolytic anemia (AIHA) happens when the physique produces an antibody towards a blood group antigen by itself crimson blood cells. The antibodies result in destruction of the crimson blood cells with ensuing anemia. Equally, a pregnant lady might develop antibodies towards fetal crimson blood cells, leading to destruction, anemia, and hydrops fetalis in a course of often known as hemolytic illness of the new child (HDN). Each AIHA and HDN could also be extreme when attributable to anti-Kell antibodies,[9] as they’re probably the most immunogenic antigens after these of the ABO and Rhesus blood group programs.
McLeod phenotype[edit]
McLeod phenotype (or McLeod syndrome) is an X-linked anomaly of the Kell blood group system during which Kell antigens are poorly detected by laboratory exams. The McLeod gene encodes the XK protein, a protein with structural traits of a membrane transport protein however of unknown perform. The XK seems to be required for correct synthesis or presentation of the Kell antigens on the crimson blood cell floor.
Historical past[edit] – “k protein in blood”
The Kell group was named after the primary affected person described with antibodies to K1, a pregnant lady named Mrs. Kellacher in 1945.[10] Mrs. Cellano was likewise a pregnant lady with the primary described antibodies to K2. The K0 phenotype was first described in 1957 and the McLeod phenotype was present in Hugh McLeod, a Harvard dental scholar, in 1961.[11][12]
King Henry VIII of England might have had Kell-positive blood sort, explaining the deaths of seven of his ten kids at, or quickly after, start, and suggesting that his psychological deterioration round age 40 could possibly be defined by McLeod Syndrome;[13] this was supported by the revelation that Henry might have inherited Kell from his maternal great-grandmother, Jacquetta of Luxembourg.[14]
Different associations[edit]
Proof helps a genetic hyperlink between the Kell blood group (on chromosome 7 q33) and the flexibility to style phenylthiocarbamide, or PTC, a bitter-tasting thiourea compound.[15][16] Bitter style receptor proteins within the style buds of the tongue that recognise PTC are encoded on close by chromosome locus 7 q35-6.
References[edit]
“k protein in blood”