Blood Bank Systems and Their Characteristics

Kidd Antibodies

Common Cause of Delayed Hemolytic Transfusion Reactions:
- Kidd antibodies can be significant because they are difficult to detect in the blood, displaying gradually declining titers post-exposure.
- They often form as a reaction to pregnancy or transfusion.
- Their low initial titers allow for a delayed response, making these antibodies a frequent cause of delayed hemolytic transfusion reactions (DHTR).
Clinical Significance of Kidd Antibodies:
- Have been implicated in cases of hemolytic disease of the fetus and newborn.
- Rare examples of autoantibody Jka observed in conditions such as warm autoimmune hemolytic anemia and drug-induced hemolytic anemia.

Characteristics of the Lutheran Blood Group System:
- The LU locus is linked with the SE (secretor) locus affecting various blood group antigens.
- There are 19 Lutheran antigens, with Lua (low frequency) and Lub (high frequency) being the most notable.
- These antigens differ due to amino acid changes in the Lutheran glycoprotein sequence.
Possible Lutheran Phenotypes:
- Lu(a+b-), Lu(a-b+), Lu(a-b-).
- The Lu(a-b-) phenotype can arise from different genetic mechanisms:
- Dominant InLu suppressor gene (located elsewhere than LU) that inhibits expression.
- Recessive LuLu gene, requiring two null alleles producing anti-Lu3 when exposed to positive antigens.

Anti-Lua:
- Generally uncommon, can occur naturally, tends to react at lower temperatures (22°C).
- Primarily saline reactive and not usually clinically significant.
Anti-Lub:
- Rare, typically produced after transfusion or pregnancy, usually of IgG type and clinically significant leading to hemolytic reactions.
Anti-Lu3:
- Rare antibody appearing in Lu(a-b-) individuals, significant and linked with mild transfusion reactions.

Characteristics of the Lewis Blood Group System:
- Unique Non-Intrinsic Antigens: Lewis antigens arise from type 1 glycolipids adsorbed onto the RBC membrane rather than synthesized directly by them.
- Lewis antigens are primarily in plasma and body secretions (e.g., saliva, tears).
Clinical Significance:
- Important in transfusions, as anti-Lea and anti-Leb are usually naturally occurring antibodies that do not typically cause hemolysis due to their neutralization by soluble Lewis antigens present in transfusions.
- Reactivity of these antibodies can be enhanced through techniques using enzyme-treated cells or neutralization with soluble Lewis antigens.
Lewis Phenotypes:
- Secreto genes and Antigen Secretion:
- Se gene affects the ability to produce Lewis antigens in secretions, with about 80% of the population being secretors, while 20% are non-secretors.
Development of Lewis Antigens After Birth:
- Lewis antigens are not well developed at birth; they begin to appear in plasma and on RBCs shortly afterward, reaching full development around the age of 6-7 years.
Biological and Clinical Implications:
- Associated with a variety of diseases including peptic ulcers, ischemic heart disease, and various cancers.

The M and N antigens are linked to glycophorin A, while S and s are on glycophorin B.
Antigen Differences:
- M antigen: Defined by serine at position 1 and glycine at position 5.
- N antigen: Defined by leucine at position 1 and glutamic acid at position 5.
Common MNS Blood Types:
- M+N-, M+N+, M-N+, S+s-, S+s+.

Anti-M & Anti-N:
- Naturally occurring; usually IgM and not clinically significant unless they exhibit reactivity at higher temperatures.
- Commonly act as cold agglutinins.
Anti-S and Anti-s:
- Uncommon; typically IgG and immune, associated with clinically significant transfusion reactions and hemolytic disease of the fetus and newborn.

P-antigens are produced through glycosyltransferases acting on lactosylceramide precursors.
P Blood Group Antigens:
- P, P1, Pk, and Luke; variation in antigen expression based on genotypes.
- Predominantly expressed in red blood cells and occasionally in plasma.

Anti-P1:
- Common antibody found in P2 individuals, mostly IgM, considered clinically insignificant unless reactive at 37°C.
Anti-P:
- Clinically significant, IgG type, can cause severe reactions including miscarriage in women with p phenotype.
Anti-Pk:
- Rare, found in p individuals, carries significant risk for transfusions.

Fy(a-b-):
- Notable because it grants resistance to Plasmodium vivax, the malaria-causing agent.
- Well expressed at birth but destroyed by proteolytic enzymes.

Anti-Fya & Anti-Fyb:
- Typically IgG, significant in HDFN and transfusion reactions, often reactive in the antiglobulin phase.

The product of the JK gene is a urea transporter, linked to phenotypes Jka, Jkb, and Jk(a-b-).

Anti-Jka & Anti-Jkb:
- Known for weak reactions, subject to antibody dosages, often difficult to detect due to fading.
- Associated with delayed hemolytic transfusion reactions and potential clinical significance.

Rare blood group antibodies and complex blood group systems may necessitate specialist laboratory involvement for problem resolution.
- Regular laboratory techniques may fail to identify all antibody complexities; advanced serological methods might be essential for accurate diagnosis and transfusion compatibility.
Enzyme Reactions:
- Treated with various reagents that can significantly alter antibody detection, understanding their specificity and effects on antigen expression is vital for blood transfusion protocols in practice.