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2340 Part XIII: Transfusion Medicine Chapter 136: Erythrocyte Antigens and Antibodies 2341

RED CELL ANTIGENS IN HEALTH AND Plasmodium knowlesi. These parasites attach to the Fy(a–b–) RBC mem-
brane, but penetration does not take place. The Fy6 antigen is the crit-
DISEASE ical receptor for P. vivax attachment. Plasmodium falciparum attaches
5
to RBC glycophorins and their O-linked oligosaccharides (carrying
EXPRESSION OF RED CELL ANTIGENS IN NeuAc). RBCs with the following phenotypes have a decreased rate of
OTHER BODY TISSUES AND FLUIDS infection: M–N– (GPA-deficient), S–s–U– (GPB-deficient), Ge– (Leach
Antigens in the RH and JK blood group systems are present only on type or GPC/GPD-deficient), and Cad-positive and Tn-positive RBCs
RBCs and have not been detected on platelets, lymphocytes, or granulo- (which have abnormal O-linked sugars).
cytes or in plasma, other body tissues, or secretions (saliva, milk, amni-
otic fluid). 4–6,16 Antigens in MNS, LU, KEL, and FY systems are found on DISEASES ASSOCIATED WITH ALTERED
RBCs and other body tissues (see Table 136–2). ANTIGEN EXPRESSION
ABH antigens have broad tissue distribution. In embryos, A, B, and
H antigens are detectable on all endothelial cells and all epithelial cells Antigen expression can be altered with inherited or acquired disease.
except those of the central nervous system. Antigens in ABO, P1PK, LE, Inherited changes are fixed and consistent; acquired changes can disap-
H, and I systems are in plasma and on platelets and lymphocytes. Gran- pear with remission or recovery. In some diseases, antigen expression
ulocytes carry I antigen but no ABH. ABH on platelets and lymphocytes weakens; in others, antigen expression increases or new antigens appear.
may be acquired at least in part by adsorption from plasma. Lewis anti- Weakened ABH expression on RBCs has been noted in acute
5,16
gen is acquired by RBCs by adsorption. Secretions (saliva, milk, sweat, myeloid leukemias and may result from reduced transferase activity.
semen, and urine, but not cerebral spinal fluid) contain soluble A, B, H, Normal antigen expression returns with disease remission. Transient
I, and Le and Le antigens but no P1PK or GLOB system antigens. Sd a weakened expression of target antigen also occurs in some cases of auto-
a
b
antigen is found in most body secretions, with the greatest concentra- immune hemolytic anemia. Weak Rh, Kell, Kidd, LW and AnWj blood
5,16,40
tion in urine. 5,16 group activity has been reported with concurrent autoantibody.
Increased expression of i on RBCs is associated with inherited
disorders, such as thalassemia, sickle cell disease, Diamond-Blackfan
ASSOCIATIONS OF RED CELL syndrome, and hereditary erythroblastic multinuclearity with a positive
ANTIGENS WITH DISEASE acidified serum test (HEMPAS). Increased i expression also is noted
with acquired conditions that decrease the red cell maturation time in
the marrow, such as myeloblastic or sideroblastic myeloblastic erythro-
ANTIGENS ASSOCIATED WITH POSSIBLE poiesis, refractory anemia, and excessive phlebotomy. 16,23 Expression of
SUSCEPTIBILITY TO DISEASE the de novo antigen Tn is caused by a galactosyltransferase deficiency
Some blood groups are statistically associated with medical conditions acquired by somatic mutation in a population of stem cells. The anti-
or disease (Table 136–4). 4–6,16 For example, blood group A is more com- gen is present on RBCs, platelets, and granulocytes arising from these
mon in persons with cancer of the salivary glands, stomach, colon, or stem cells. This condition (seen as persistent mixed-field agglutination
ovary and with thrombosis (because of higher levels of coagulation fac- because of the presence of both normal and abnormal cells) causes
tors VIII, V, and IX). Blood group O is more common in patients with other RBC changes, such as depressed MN expression, enhanced H, and
duodenal and gastric ulcers, rheumatoid arthritis, and von Willebrand reduced NeuAc content. Tn antigen exposure is associated with mye-
16
disease. lodysplastic syndrome and acute myelomonocytic leukemia. Other
Associations with infection arise when microorganisms carry antigens (T, Tk) occur as a result of infection when microbes produce
structures homologous with blood group activity. The presence of enzymes that remove some sugars (NeuAc) and expose new ones. Group
blood group antibody and/or soluble blood group antigen in secretions A individuals can appear to acquire a B antigen when bacterial deacety-
4,16
may help confer protection. Having anti-B may offer protection against lase removes the acetyl group on GalNAc. This phenomenon is asso-
Salmonella, Shigella, Neisseria gonorrhoeae, and some Escherichia coli ciated with severe infection, gastrointestinal lesions, and malignancies.
infections. An association exists between nonsecretion of ABH antigen RBCs may acquire blood group activity when they adsorb material
and susceptibility to Candida albicans, Neisseria meningitidis, Strepto- from certain microorganisms. Group B activity has been associated with
86
coccus pneumoniae, and Haemophilus influenzae. 6 E. coli and Proteus vulgaris infection, and K antigen with Enterococcus
b
A number of disease associations with globoside have been iden- faecium. Acquired Jk -like activity has been associated with E. faecium
tified. Streptococcus suis, which can cause meningitis and septicemia in and Micrococcus infections, although the mechanism is not clear. 41
humans, binds exclusively to P antigen. A class of toxins secreted by
k
Shigella dysenteriae, Vibrio cholerae, and Vibrio parahaemolyticus have DISEASES ASSOCIATED WITH ABSENT
binding specificity for Gal(α1–4)-Gal(β1–4). In addition, globoside is
the receptor of human parvovirus B19. Some strains of E. coli use the ANTIGENS OR NULL PHENOTYPES
disaccharide receptor Gal(α1–4)-Galβ on uroepithelial cells to gain Rh Syndrome
null
entry to the urinary tract receptors associated with P1, P , and P anti- The Rh phenotype is associated with hereditary stomatocytosis,
k
null
gens. People with the rare p phenotype lack this disaccharide and are hemolytic anemia (usually mild and well compensated), and a lack
5,33
not susceptible to acute pyelonephritis from such E. coli strains nor to of proteins carrying Rh antigens. The Rh protein resides in the RBC
infection by human parvovirus B19. membrane, interacts with other membrane proteins and possibly the
membrane skeleton, and may help regulate or organize the lipids within
9,10
PHENOTYPES ASSOCIATED WITH DISEASE the red cell membrane bilayer. Hence, it is an important determinant
of membrane shape and expression of other antigens. Rh cells have
RESISTANCE depressed expression or absence of S, s, U, LW, and Fy5 antigens.
null
Erythrocytes lacking Fy and Fy antigens are not infected by the Most Rh red cells are stomatocytes or occasionally spherocytes
b
a
null
malarial parasite Plasmodium vivax or by the simian malarial parasite and demonstrate increased osmotic fragility, increased potassium

Kaushansky_chapter 136_p2327-2352.indd 2340 9/21/15 4:31 PM