Faculty of Allied Medical Science Blood Banking (MLBB 201)

Lewis and Kell Blood Groups Prof.Dr. Nadia Aly Sadek Blood Bank Director, MRI

Outcomes By the end of this lecture, the students will be able to: By the end of this lecture, the students will be able to: Recognize the Lewis and Kell blood group antigens Recognize the Lewis and Kell blood group antigens Know their clinical importance Know their clinical importance

Lewis antigens are carbohydrate structures carried on glycolipids. They differ from other blood groups in that they are not produced by RBCs, but they become incorporated into the red cell membrane from the plasma. Lewis antigens are carbohydrate structures carried on glycolipids. They differ from other blood groups in that they are not produced by RBCs, but they become incorporated into the red cell membrane from the plasma.

Types of Lewis antigens There are two main antigens:- 1- Le a 2- Le b There are 4 Lewis phenotypes:- 1- Le (a+b-): only found in ABH non- secretors 2- Le (a-b+): only found in ABH secretors

3- Le (a+b+) only found in ABH secretors 3- Le (a+b+) only found in ABH secretors 4- Le (a-b-) RBCs have no Lewis antigens 4- Le (a-b-) RBCs have no Lewis antigens Lewis antibodies are only made by individuals with the Le (a-b-) red cells. They are not clinically significant as they are not active at 37 degrees.

Kell system It includes K (KEL 1) with a frequency of 9% in Northern Europeans and 1.5% in African populations. The k (KEL 2) antigen is of high frequency in all populations. (KEL 3) is found in about 2% of Caucasians but not present in Africans or Japanese.

(KEL 4) is of high frequency in all populations. (KEL 4) is of high frequency in all populations. (KEL 6) is completely confined to African individuals. (KEL 6) is completely confined to African individuals.

Kell antibodies These antibodies are clinically significant. They cause severe hemolytic disease of fetus and newborn (HDFN) as well as hemolytic transfusion reactions. These antibodies are clinically significant. They cause severe hemolytic disease of fetus and newborn (HDFN) as well as hemolytic transfusion reactions. Patients with Kell antibodies should be transfused with antigen-negative blood. Patients with Kell antibodies should be transfused with antigen-negative blood.

Kell system antibodies are usually IgG and predominantly (IgG1).

Difference between HDFN due to anti-K or anti-D 1. Anti-K HDFN is associated with lower concentrations of amniotic fluid bilirubin concentration than anti-D HDFN. 2. Post- natal hyperbilirubinaemia is not prominent in babies with anti-K.

3. There is reduced reticulocytosis and normoblast % in the anti-K disease. 4. Kell antigen appears on early erythroid cells much before the Rh antigen. Kell negative girls and women of child- bearing age should receive K- blood transfusion.

Detection of Kell antibodies Anti-K directly agglutinate K+ red cells. -Antiglobulin test is the method of choice for their detection.

Universal Blood group A and B antigens on red cells can be removed, in vitro, by converting them back to the H antigen. This is done by removal of the immunodominant sugar with an appropriate enzyme. They become group O. These enzymes are obtained from bacteria (A-zyme) and green coffee beans (B-zyme).

Study question State true or false:- 1- Lewis antigens are produced by the RBCs 2- Le (a-b+) are only found in ABH secretors 3- Le (a-b-) have antigens on RBCs

Assignments Plasma Exchange Plasma Exchange عائشة خضر احمد

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