Kidd Blood Group System

• Kidd Blood Group System has an ISBT no. 009 with symbol JK
• Kidd (JK) System has gene: SLC14A1; Chromosome: 18
• 3 JK antigens

  • Jka
  • Jkb
  • Jk3
• Jk system has also identified in Filipinos, Indonesian and Chinese populations
• Kidd Antigens (Jkᵃ and Jkᵇ) are commonly found on RBCs of most individuals
• Kidd Antigens (Jkᵃ and Jkᵇ) are well developed on the RBCs of neonates
• Jkᵃ has been detected on fetal RBCs as early as 11 weeks
• Jkᵇ has been detected at 7 weeks
• Kidd Antigens (Jkᵃ and Jkᵇ) are resistant to proteolytic enzymes (ficin or papain)
• Kidd Antigens (Jkᵃ and Jkᵇ) are poor immunogens that are not affected by chloroquine, DTT, AET, or glycine-acid EDTA.
• Kidd Antigens (Jkᵃ and Jkᵇ) are not found on platelets, lymphocytes, monocytes, or granulocytes.
• Kidd antibodies (anti-Jkᵃ and anti-Jkᵇ) demonstrate dosage effect and often weak reaction and found in combination with other antibodies
• Kidd antibodies (anti-Jkᵃ and anti-Jkᵇ) usually, IgG but may be partly IgM and are made in response to pregnancy or transfusion
• Kidd antibodies (anti-Jkᵃ and anti-Jkᵇ) are reactive at AHG phase and reactivity can be enhanced by using LISS or PEG
• Kidd antibodies (anti-Jkᵃ and anti-Jkᵇ) binds complement. Rare Kidd antibodies are detected only by complement they bind (ex. They are non-reactive in antiglobulin phase of testing using anti-IgG reagents)
• The titer of the anti-Jkᵃ and anti-Jkᵇ quickly declines in vivo. A strong antibody identified following a transfusion reaction may be undetectable in a few weeks or months.
• Kidd antibodies (anti-Jkᵃ and anti-Jkᵇ) are commonly associated with hemolytic transfusion reactions and rarely associated with severe cases of HDFN
• Anti-Jk3 is produced by individuals with Jk(a-b-) and reacts optimally in AHG phase
• Alloanti-Jk3 is an IgG antiglobulin-reactive antibody
• Anti-Jk3 reactivity is enhanced with enzyme pre-treatment of the RBCs and has been associated with severe immediate and delayed HTRs and with mild HDFN.