Chapter 35 Immunohematology

Front 1

3 characteristics of antigens that determine immunogenicity?

Back 1

immunogenicity is the ability of an antigen to elicit an immune response; 3 characteristics contributing to immunogenicity sre degree of foreignness, molecular size and configuration, and complexity

Front 2

which two antigens have the greatest number of antigenic sites

Back 2

A and B; this is why they are so immunogenic

Front 3

the initial direct antiglobulin(DAT) detects immunoglobin or complement binding in vivo with both polyspecific antihuman globulin and anticomplement antibodies
what class of immunoglobulin and complement components are targets?

Back 3

IgG is the immunoglobin, C3d and C3b are the cheif complement component

Front 4

what lectin is used to identify the A1 subtype of A

Back 4

Dolichos biflorus

Front 5

differentiate between B(A) phenotype and the acquired B phenotype

Back 5

in B(A) the person is naturally type B but he synthesizes a trace amount of A antigen; this is an autosomal dominant condition
in acquired B, bacteria or a colon cancer (possibly damaging the integrity of the bowel wall and allowing bacteria into the bloodstream) induces the deacetylation of the A antigen to form a B-like antigen

Front 6

serology of the classic Bombay individual with se/se

Back 6

Bombay persons have antibodies to A, B and H. They lack all three antigens on their red blood cells; they have the se/se genes, they also lack secretions of A, B or H

Front 7

the H antigen formed by adding fucose to a terminal galactose on type 1 or 2 chain precursors, is the building block of both the A and Bantigen
both A and B genes code fro glucosyltransferases. what molecule does each glycosyltransferase add to the H antigen

Back 7

A antigen has N-acetylgalactosamine
B antigen has galactose

Front 8

intravascular hemolysis is seen with with what two red cell antigens?

Back 8

intravascular hemolysis is seen with ABO and Kidd

Front 9

R indicates, r indicates?
superscript 0 or lack of superscript?
superscript 1 or '?
superscript 2 or ''?
superscript Z or y?

Back 9

order is DCE, upper or lower case
D,d
R0=Dce; second and third positions are lower case
R1=DCe; second position only is upper case
R2=DcE; third position is upper case
RZ=DCE; both second and third position are upper case

Front 10

most common Rh haplotype in African Americans

Back 10

in African Americans, Dce or R0 is most common

Front 11

most common Rh haplotype in US Caucasians

Back 11

in US Caucasians, DCe or R1 is most common

Front 12

most common cause of the weak D phenotpye?

Back 12

weak D is most most frequently caused by the autosomal recessive RhD mutant allele

Front 13

why are persons with partial D more likely to make anti-D antibodies than those with weak D?

Back 13

partial D lack certain epitopes on their D antigens. if transfused with D-positive blood, they make antibodies to those D epitopes which lack but which the donar has. individuals with weak D, in contrast, usually have normal extracellular loops with normal D epitopes. they do not see anything foreign in donor D

Front 14

the Rh null phenotype is extremely rare
morphology of red cells?
osmotic fragility?
Fy5, LW antigens?
SsU antigens?

Back 14

sphereocytes due to reticuloendothelial culling and stomatocytes (fairly characteristic), increased osmotic fragility, absent Fy5 and LW antigens, marked decreased SsU. the LW antigens are expressed best with RhD

Front 15

the type 1 chain is the precursor molecule fro all Lewis antigens. It is the precursor substrate for both the Lewis and ?? genes, both of which are fucosyl transferases

Back 15

secretor

Front 16

to generate a Le(a+b-) phenotype, one must have at least one ??gene, but lack the ??gene
by contrast, the Le(a-b+) phenotype requires both the ?? and ?? genes

Back 16

the Le(a+b-) individuals have at least one Le gene, but lack Se. you need Se to make Le b.
the Le(a-b+) individuals have both Le and Se, at least one of each

Front 17

give two reasons why anti-Lewis antibodies are not associated with hemolytic disease of the newborn (HDN)?

Back 17

antibodies to Lewis are IgM, andthus do not cross the placenta. fetal RBCs lack Lewis antignes, so there is nothing foreign for the mother to see

Front 18

the Lewis, P and I groups antigens have several features in common
biochemical class:
antibody isotype:
HDN capacity:
clinical significance of antibodies:
antibody reaction temperature:

Back 18

Lewis, P and I system antigens are all glycosphingolipids;
I has other carbohydrate forms as well
they elicit IgM antibodies, do not cause HDN, are usually benign, and react at room temperature

Front 19

the occurrence of cold autoimmune hemolytic anemia; this occurs in association with mycoplasma pneumonia with antibodies to??

Back 19

anti-I is associated with mycoplasma pneumonia, and also malignancy

Front 20

The MNSs blood group demonstrates some variation in terms of the clinical significance of antibodies to its antigens.
Which antibodies are always significant?
When is anti-N significant?

Back 20

Anti-S, s or U is always clinically significant;
Rare persons who are SsU-- (they lack the glycophorin B molecule) anti-N can be quite serious

Front 21

Who's t is the biological role of the Lutheran antigen, and in what population/disease can increased expression result in circulatory stasis?

Back 21

The Lutheran antigen is a receptor for laminitis and is thought to mediate cell adhesion; in sickle cell disease patients, Lutheran is believed to mediate adherence of red cells to the vessel walls, causing stasis

Front 22

in 9% of caucasians are K+k+ and 91% are K-k+.
?frequencies in African Americans(AA)

Back 22

2% AA are K+k+
98% are K-k+

Front 23

the Kell antigen is covalently linked to the XK protein on the red cell surface, a complex integral membrane protein whose function is not yet clear. absence of the XK protein is associated with the decrease expression of the Kell antigen. This is called ??.

Back 23

this is McLeod phenotype. the defect is with the XK protein, not with the Kell antigen per se. red cells have a shortened survival; some are acanthocytes

Front 24

what x-linked disease is associated with the McLeod phenotype?

Back 24

the gene for chronic granulomatous disease is on the X chromosome near the gene for the XK protein; 7% of CGD patients have the McLeod phenotype, suggesting a two gene insult

Front 25

what is the evolutionary advantage of the Fy(a-b-) phenotype?

Back 25

the Fy(a-b-) phenotype offers protection against plasmodium vivax. The binding site for P.vivax is the integral membrane protein where the Duffy antigens reside

Front 26

53 yom who is Jk(a+b-) received several units of RBCs for a GI bleed 6 months ago. Now, he is back with another GI bleed and requires RBCs. The antibody screen is negative , and the crossmatch is compatible with Jk(a+b+) RBCs. One week after receiving the transfusion, the man's hematocrit falls from 34% to 27% in one day. His bilirubin is 3.2mg/dL. Schitocytes are seen on the peripheral smear. What happened?

Back 26

the delayed hemolytic transfusion reaction is classic with Kidd; the recipient received Jk(b+) RBCs with his earlier transfusion, made antibodiesto Jk(b), but had a fall in his antibody titer over the 6 months, with the current transfusion he had an anamnestic reponse with both intravascular and extravascular hemolysis

Front 27

the Colton blood group antigens reside on which integral membrane protein?

Back 27

this is the aquaporin 1 (AQP-1), water selective membrane channel found on RBC and several renal epithelial cells; it facilitates urine concentration in the kidney; but interestingly Colton-null persons show no ill-effects in terms of renal function

Front 28

LW antigens might be absent in a patient with stomatocytes. True or False

Back 28

True. the Rh null phenotype is associated with stomatocytes, and RhD antigen is linked to LW expression

Front 29

what is the purpose of the immediate spin crossmatch?

Back 29

used to detect ABO incompatibility. it is the last chance to detect a potentially fatal ABO incompatibility error before a unit of red cells leaves the blood bank to be transfused to a patient

Front 30

how do enzymes such as papain or ficin enhance agglutination in general?
why are the M and N antigens destroyed by theses enzymes?

Back 30

enzymes remove sialic acid residues on the surface of red cells, reducing their negative charge; recall that M and N antigens sit right on those sialic acid residues, so they are removed as well

Front 31

what autoimmune hemolytic anemias are usually positive only in the C3d p[hase of a direct antiglobulin test(DAT)?

Back 31

these are cold hemaagglutinin disease (CHD) and paraxymal cold hemaglobinuria (PCH); CHD is usually due to anti-I; PCH is due to anti-P

Front 32

AABB standard for the age of a sample for compatibility testing?

Back 32

if a patient has had a tranfusion or has been pregnant in the past 3 months, then a 72 hour clock starts ticking any time he or she has a blood sample drawn for compatibility testing. any cross match and/or transfusion must take place within 72 hours ot that sample being drawn

Front 33

By AABB standards, donors testing Rh-negative must be confirmed with the weak D test, weak D testing of recipients is optional. True or False

Back 33

True; if a recipient is assumed to be D-negative but is actually D-positive and gets D-negative blood--no harm is done

Front 34

what is suggested by the fact that there are different reactions seen in different phases (37*C vs AHG)?
what does the 2+ CC in panels 3 and 5-7 indicate?
whta does the negative autocontrol suggest about the patient's transfusion history?

Back 34

Hint 34

multiple antibodies are suggested when you have a mixed picture in the reaction columns; the CC are the check cells, theses are the cells which are coated with IgG and C3 and used to confirm negative results;

Front 35

four cells 3,5,6 and & show no reaction in either phase; they may be used to rule out certain antigens. the homozygous rule states that in order to rule out an antigen, it must be homozygous in that cell; observe that e is homozygous in cell 1 (E is not present); but that it is heterozygous in cell 4 (E is present); using the homozygous rule what antigens can be rulled out

Back 35

Hint 35

anti-D,C, c,e,f,V,M,N, s, P1,Lea,Leb, Lub, k, Fyb, Jka, JKb

Front 36

possible antigens?

Back 36

Hint 36

E,Cw,S,Lua, K, Kpa, Jsa, and Fya

Front 37

which two cells show reaction in the 37*C phase with a stronger reaction in the AHG phase?
this is a common pattern in the Rh system; which of the Rh antigens is left, and is it positive in these two cells?

Back 37

Hint 37

cells 4 and 10 are positive at 37*c and stronger at AHG. Yhe only Rh antigen left is E; it is positive in cells 4 and 10 only; so it is a good fit; ant E is the first antibody

Front 38

which two cells show a strong reaction in the AAHG phase only?
which of the remaining antigens is positive in these two cells?

Back 38

Hint 38

cells 2 and 8 are positive in AHG only; this is characteristic of Kell and K is positive in 2 and 8 only; so that fits; Anti-K is the second antibody

Front 39

cells 1,9, and 11 give a 1+ reaction only in the AHG phase and this may be due to a single, third antigen; which of the remaining antigens is positive in all three of these cells

Back 39

Hint 39

cells 1,9, and 11 all have the same pattern and of the antigens left, only Fya is positive in all three of these cells. Anti Fya is the third antibody

Front 40

what is the immunoglobulin class in warm autoimmune hemolytic anemia?
what is the optimal temperature of reaction?
are these antibodies always specific for a particular antigen?

Back 40

warm autoantibodies are usually IgG, most often IgG1 or IgG3; react at 37*C; are broadly reactive rather than specific to a single red cell antigen