KELL BLOOD GROUP Flashcards
ANTIGENS
How does the expression of the K0 (Knull) phenotype affect Kell antigen presence on red blood cells?
The K0 (Knull) phenotype results from mutations in the KEL gene, leading to the complete absence of Kell antigens on red blood cells. Individuals with this phenotype lack all Kell antigens and can develop anti-Kell antibodies if exposed to Kell-positive blood.
What are the primary Kell antigens, and what is the difference in immunogenicity between K and k antigens?
The primary Kell antigens are K (Kell) and k (Cellano). The K antigen is highly immunogenic, meaning it can trigger a strong immune response, whereas the k antigen is much more common but less immunogenic.
What implications do anti-Kell antibodies have for hemolytic disease of the newborn (HDN)?
Anti-Kell antibodies can cross the placenta and destroy the fetal red blood cells expressing Kell antigens, leading to hemolytic disease of the newborn (HDN). This can cause severe anemia and jaundice in the newborn, requiring close monitoring and possible intrauterine transfusions.
Describe the role of the Kpb and Jsb antigens in the Kell blood group system and their clinical significance.
Kpb and Jsb are high-frequency antigens within the Kell blood group system. Due to their high prevalence, antibodies against these antigens (anti-Kpb and anti-Jsb) are relatively rare but can cause hemolytic transfusion reactions if present. They are clinically significant because finding compatible blood for patients with these antibodies can be challenging.
How do the various alleles of the KEL gene contribute to the antigenic diversity within the Kell blood group system?
The KEL gene’s various alleles produce a range of Kell antigens, including K, k, Kpa, Kpb, Jsa, and Jsb. This diversity results from genetic mutations and variations within the KEL gene, leading to different antigenic profiles on red blood cells.
What is the clinical significance of the Kx antigen and its relationship to the Kell protein?
The Kx antigen, encoded by the XK gene, is associated with the Kell protein on red blood cells. Mutations in the XK gene lead to the McLeod phenotype, characterized by weakened Kell antigen expression and associated neurological and muscular symptoms. Clinically, individuals with the McLeod phenotype require careful management during transfusions to avoid hemolytic reactions.
Explain why individuals with the K0 (Knull) phenotype are at risk when receiving blood transfusions.
Individuals with the K0 (Knull) phenotype lack Kell antigens on their red blood cells and can develop antibodies against Kell antigens if exposed to Kell-positive blood. This puts them at risk for severe hemolytic transfusion reactions if not transfused with Kell-null blood.
How do anti-K and anti-k antibodies differ in their clinical impact during transfusions?
Anti-K antibodies are more clinically significant due to the high immunogenicity of the K antigen, leading to severe hemolytic transfusion reactions. Anti-k antibodies are rarer due to the high prevalence of the k antigen in the population, but they can still cause hemolytic reactions in those sensitized to the k antigen.
