Other Red Cell Blood Group Systems

Flashcards covering the major blood group systems beyond ABO and Rh, including Kell, Duffy, Kidd, MNS, Lutheran, Lewis, I, P1PK, HLA, and Platelet antigens.

K (K1) antigen

The first major antigen in the Kell system; it is found in less than $9\%$ of the population and is very immunogenic, ranking second only to the D antigen.

k (K2/cellano) antigen

A high-frequency antigen in the Kell system found in more than $90\%$ of the population, functioning as the antithetical antigen to K (K1).

Sulfhydryl reagents (2-ME, DTT, AET)

Chemical substances used to treat RBCs that destroy Kell antigens by breaking the disulfide bonds on their glycoproteins.

K0 or Kellnull phenotype

A rare phenotype that lacks all Kell system antigens but expresses the Kx antigen; individuals with this phenotype can develop anti-Ku.

anti-Ku

A clinically significant antibody produced by K0 individuals following immune stimulation; it reacts with all RBCs that possess Kell system antigens.

McLeod phenotype

A rare condition seen mostly in white males where the Kx antigen is absent, leading to RBC abnormalities like acanthocytosis and muscular defects.

McLeod syndrome

A condition associated with acanthocytosis, increased creatine kinase, and chronic granulomatous disease, resulting from the lack of the Kx antigen.

Fya (FY1) and Fyb (FY2)

Codominant alleles in the Duffy blood group system that are well developed at birth and are destroyed by proteolytic enzyme treatment.

Fy(a–b–) phenotype

A phenotype found frequently in West and Central Africa that provides resistance against Plasmodium knowlesi and Plasmodium vivax malarial parasites.

Duffy Antibodies (Anti-Fya, Anti-Fyb)

IgG antibodies that react best at the AHG phase and often show dosage, reacting more strongly with homozygous cells like Fy(a+b-).

Kidd null phenotype (Jk(a–b–))

A rare phenotype seen mostly in individuals from the Far East or Pacific Islands where RBCs are uniquely resistant to $2M$ urea.

Kidd Antibodies (Anti-Jka, Anti-Jkb)

Clinically significant IgG antibodies that often bind complement and are a common cause of delayed hemolytic transfusion reactions.

Lua and Lub

The primary antigens of the Lutheran blood group system; antibodies to these often show a characteristic mixed-field pattern in vitro.

Glycophorin A (GPA)

The membrane structure consisting of $131$ amino acids that carries the M and N antigens; these antigens differ at positions $1$ and $5$.

Glycophorin B (GPB)

The membrane structure consisting of $72$ amino acids that carries the S, s, and U antigens.

U antigen

A high-incidence antigen located near the membrane on GPB; it is present whenever S or s is inherited, but absent in less than $1\%$ of the black population.

N-like antibodies

Antibodies found in dialysis patients that result from the use of formaldehyde-sterilized instruments.

Lewis system adsorption

The process by which Lewis glycolipids from the plasma stick to the surface of the RBC membrane, as Lea and Leb are not intrinsic to the RSC membrane.

i antigen

A linear antigen found on cord cells of newborns that converts to the branched I antigen as a child matures to about $2$ years of age.

Autoanti-I

A common cold-reacting IgM autoantibody associated with Mycoplasma pneumoniae and cold hemagglutinin disease.

Donath-Landsteiner antibody

An autoanti-P (IgG) that acts as a biphasic hemolysin, associated with paroxysmal cold hemoglobinuria in children after viral infections.

HLA Class I

Antigens found on platelets, leukocytes, and nucleated cells, which are coded by genes within the Major Histocompatibility Complex (MHC).

HLA Class II

Antigens found on macrophages, dendritic cells, and B cells, used for matching in organ and HPC transplants.

HPA-1a (P1A1)

The most common platelet antibody target, present in $98\%$ of the population, and frequently involved in Neonatal Alloimmune Thrombocytopenia (NAIT).