tailieunhanh - Ebook Essential guide to blood groups (3/E): Part 2

Part 2 book “Essential guide to blood groups” has contents: Other blood groups, clinical significance of blood group antibodies, blood grouping from DNA, quality assurance in immunohaematology, trouble-shooting and problem-solving in the reference laboratory, frequently asked questions. | Other blood groups c hapter 5 ABO and Rh are the most clinically significant and best known of the blood group systems, yet there are 31 other systems of diverse clinical and biological relevance (see Table ). In addition, there are other antigens, which have not been allotted to a system, most of which either are of very high or very low frequency. The Kell system The antigen often referred to as Kell, but correctly named K or KEL1, is the original antigen of the Kell system and the first blood group antigen to be identified following the discovery of the antiglobulin test in 1946. The Kell system now consists of 35 antigens numbered from KEL1 to KEL38, with 3 obsolete. Six pairs and one triplet of Kell antithetical antigens are listed in Table . The Kell glycoprotein and the KEL gene The Kell system antigens are located on a red cell membrane glycoprotein that is N-glycosylated, but not O-glycosylated (see Chapter 1). It spans the membrane once and is unusual because its short N-terminal domain is in the cytosol and its large C-terminal domain is outside the membrane (see Fig. ). The extracellular domain has five or six N-glycosylation sites and 15 cysteine residues, and is extensively folded by disulphide bonding. Kell system antigens are sensitive to disulphide bond reducing agents such as dithiothreitol (DTT) and 2-aminoethylisothiouronium bromide (AET). The Kell protein has structural and sequence homology with a family of zinc-dependent endopeptidases that process a variety of peptide hormones. Although the function of the Kell glycoprotein is not known, Essential Guide to Blood Groups, Third Edition. Geoff Daniels and Imelda Bromilow. © 2014 John Wiley & Sons, Ltd. Published 2014 by John Wiley & Sons, Ltd. 49 50 | Chapter 5 Table   Antithetical antigens of the Kell blood group system. Relative frequency High Molecular basis Polymorphic in: Low k KEL2 K KEL1 Thr193Met Caucasians, .