Kell Blood Group System

• Kell Blood Group System has an ISBT no. 006 with symbol KE
• Kx Blood System has an ISBT no. 19 with symbol XK
• KEL gene located in chromosome 7
• KEL system consists of 36 unique antigens and 6 of these antigens are of interest
• Low-prevalence antigen Jsᵃ and its antithetical high-prevalence antigen Jsᵇ
• Low-prevalence antigen Kpᵃ and its antithetical high-prevalence antigen Kpᵇ
• Low-prevalence antigen K and its antithetical high-prevalence antigen k
• K₀ or Kₙᵤₗₗ red cells lack all KEL system antigens
• Immunized individuals produce anti-Kᵤ, or anti-KEL5 requiring transfusion of K₀ red cells
• Kx Blood System has Kx antigen
• Kx antigen is located on the X chromosome
• Kx antigen is present in all RBCs except those of the rare McLeod phenotype
• RBC that lacks the Kx antigen also have weakened expression of the other Kell system antigens.
• K₀ and Kmod RBCs have increased Kx antigen
• When Kell antigens are denatured with AET or DTT, the expression of Kx increases
• McLeod red cells express diminished amounts of KEL antigens and lack the high-prevalence antigens Kx and Km
• McLeod syndrome is a rare X-linked condition associated with acanthocytosis, chronic granulomatous disease, and various neurologic and muscular symptoms.
• Complex antibodies including anti-Kx and/or anti-Km and can be produced in immunized individuals and requires transfusion of either K0 or McLeod red cells.
• KEL system antigens can be destroyed if RBCs are treated with disulfide bond-reducing agents like dithiothreitol (DTT) and 2-aminoethylisothiouronium bromide (AET)
• K+k- individual can make anti-k
• Kp(a+b-) individual can make anti-Kpb
• Js(a+b-) individual can make anti-Jbb
• Anti-K – common alloantibody; highly immunogenic
• KEL system antibodies are usually IgG and clinically significant
• Kell System Antibodies has been associated with acute and delayed hemolytic transfusion reactions and HDFN
• K antigen is second only to D antigen in immunogenicity, and the resulting antibody is relatively common in transfusion practice.
• Anti-K are usually IgG
• Anti-K reacts bests at 37C and may occasionally bind complement and can cause HDN and HTR
• Anti-K (cellano) is rare antibody that can cause HDN and HTR
• anti-Ku, or anti-KEL5 is clinically significant. K0 patients should be transfused with K₀ cells
• For testing, K₀ cells can be prepared by treating normal RBCs with 2-aminoethylisothiouronium (AET) bromide or dithiothreitol (DTT) plus cysteine-activated papain (ZZAP)