Introduction
The body's immune system may attack the Kell antigen system, a set of surface markers on red blood cells that aid in blood type determination and can result in illnesses that kill red blood cells. These antigens belong to a protein known as the Kell protein, which is crucial for cleaving endothelin-3. The gene that produces the Kell protein is found in numerous forms. K2 (Cellano) and K1 (Kell) are the most popular. A strong connection binds the Kell protein firmly to the XK protein, another protein. Reduced amounts of Kell antigens are present on the surface of red blood cells when the XK protein is absent due to hereditary causes. It does not affect the XK protein if the Kell protein (also known as K0) is missing.
What Is the Kell Blood Group System?
Human blood is categorized using the Kell blood group system based on specific surface markers of red blood cells. The gene KEL, also known as antigens, controls these indicators. This system, which was discovered in 1946, is renowned for having a great deal of genetic variation, indicating that these antigens come in various forms. Knowing the Kell antigens enables an individual to gain insight into the evolutionary history of human genetic characteristics.
When the body develops antibodies against certain antigens, it might cause potentially dangerous reactions that can occur during pregnancy or after blood transfusions. The Kell system is the third most frequent cause of these responses, behind the Rh and ABO systems.
The KEL gene regulates each of the 25 distinct Kell antigens. The K (Kell) and k (Cellano) antigens are produced by the two primary variants of this gene, K and k, respectively. Over 90 percent of both Black and White people have the k antigen, making it a highly prevalent antigen. Different antigens, such as Jsa and Jsb, are produced by variations in the KEL gene. 80 percent of Black people and all White people carry the Jsb antigen. The Kell antigens Kpa (Penney) and Kpb (Rautenberg) are more examples.
Normally, on the surface of red blood cells, a protein known as Kx is connected to Kell antigens. However, some people lack this protein, which results in a disorder known as McLeod syndrome (an X-linked multisystem disease brought on by XK gene mutations). This disease may alter red blood cell morphology, and Kell antigen levels may drop. These anomalies frequently cause nerve and muscular disorders, which impair reflexes, cause mental health problems, and make movement difficult.
What Are Common and Rare Kell Blood Group Phenotypes?
1. Typical Kell Characteristics: There are two primary types in the Kell blood group system: K and k. Fewer people are K types, and the majority are k types. 91 percent of Caucasians and 98 percent of Black people have the K-k+ phenotype.
2. Unusual Kell Characteristics:
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Null Phenotype (Ko): This is an uncommon condition in which RBCs (red blood cells) lack the Kell antigens. In healthy individuals with this disease, exposure to RBCs containing Kell antigens may result in the development of anti-Ku antibodies. Individuals who are Ko should get blood products that do not contain Kell antigens if they require a transfusion because these antibodies can result in serious responses during the procedure.
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McLeod Syndrome: This illness is characterized by a connection between the protein XK and the Kell glycoprotein found in red blood cells. RBCs become abnormal with spiky projections, and Kell antigens are only faintly expressed when XK is lacking, as in the case of McLeod syndrome. Numerous health concerns, including muscular dystrophy, cardiac problems, mental health disorders, and neurological issues like movement impairments and reflex loss, can result from this syndrome.
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Expression of Kell Antigens: It is now known that Kell antigens are present in various cell types, such as bone marrow cells, even though they were once thought to be present in certain blood cells exclusively. They can even be found in trace amounts in the neurological system, muscles (including the skeletal and cardiac muscles), lymph nodes, and other organs.
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Functions of the Kell Glycoprotein: The Kell glycoprotein serves as an enzyme to change the form of endothelin-3 from a less active to an active version. Due to its ability to constrict blood vessels and alter blood flow, endothelin-3 is significant.
What Does the KEL Gene Control and How Does It Function?
The KEL gene is comparable to a set of instructions on DNA's chromosome 7. It comprises 19 components known as exons and is in charge of identifying the 25 distinct antigen types that make up the Kell blood group. One prevalent variation among these blood types is a small genetic alteration resulting in one amino acid (a protein's building block) changing from threonine to methionine. The immune system's reaction may differ significantly depending on this tiny alteration. Other variations in the Kell blood group are brought about by other gene mutations that alter the behavior of the protein and its amino acid composition.
The KEL gene produces the Kell protein, a lengthy chain of amino acids that is altered by adding sugar molecules at five distinct locations. It uniquely interacts with another protein called XK and adheres to the surface of red blood cells (RBCs). A disease known as McLeod's syndrome, which impacts several bodily systems, may result from XK deficiency. The Kell protein is a member of an enzyme family that cuts proteins in a particular way. Its sequence is crucial to its functionality, particularly its capacity to bind to zinc, a mineral that is necessary for its activity.
What Is the Role of Kell Antigens in Blood-Related Conditions?
Hemolytic illness of the infant, several forms of anemia, and blood transfusions are all significantly impacted by Kell antigens. Someone who obtains blood with a certain Kell antigen but lacks that antigen may develop antibodies against it. Hemolysis, a process when fresh red blood cells are destroyed, may result from this. People without Kell antigens (K0) require blood from donors who do not have Kell antigens to avoid this.
The body produces antibodies against its red blood cells by an error in autoimmune hemolytic anemia (AIHA), which results in the death of the red blood cells and anemia. Similarly, a woman's body may produce antibodies against her unborn child's red blood cells during pregnancy, which might destroy her child's red blood cells and result in anemia and other major health issues. The condition is called hemolytic disease of the newborn (HDN). As Kell antigens are highly immunogenic or trigger a powerful immune response, AIHA and HDN can be severe when anti-Kell antibodies are present.
Conclusion
Red blood cells include the Kell antigen marker, which determines blood compatibility. According to recent studies, this marker may be present in bone marrow organs and blood. Variations in the Kell gene can impact general health and immune system responses. Knowing about Kell antigens is crucial for safely administering medical treatments like blood transfusions. Examining these signs makes it possible to predict the body's reaction to transfusions. Beyond blood matching, understanding Kell differences is useful for researching various health issues.
