BL- Immunohemotology ABO/Rh Flashcards
Red cells do not carry MHC antigens in humans, and the antigens they do carry are much less __________ in the population
polymorphic
(that is, many fewer alleles).
H substance
Sugar on all red cells
*this is all O has
____________catalyse the transfer of activated carbohydrate moieties from donor molecules to an acceptor molecule.
Glycosyltransferases
Red cells do not carry:
MHC
A-morph
gene that does not code for protein
The O allele is an “amorph;”
_________assemble the basic “core” sugar chain which almost everybody has, it is called
the “H” antigen.
Glycosyltransferases
Group A blood have a glycosyl transferase allele which puts an additional sugar on the H antigen, and people who are B have a different allelic form of this enzyme which adds a___________
different sugar
There are some people who lack the transferase gene that puts the final sugar on the “core”, and thus do not express even the H antigen, so there is no substrate for the A or B glycosyltransferases to modify.
Blood type?
This is the Bombay phenotype (Oh,) and it is rare
Can bombay blood groups have blood transfusions?
only from Bombay, cannot accept O
Group A and B blood group genotypes can include
O geneotype
ex: you may be AA or AO
A blood make anit____
anti b
B blood make anit___
anti a
O blood make anit___
anti a and anti b
AB blood make anit___
Nothing, no anti’s
Bombay makes anti_____
everything, A B O
Needs xfuision from bombay
The second most important blood group system is _______, so called because it was discovered by workers studying rhesus monkeys.
Rh
Rhesus (Rh) factor is an inherited trait that refers to a specific protein found on the surface of red blood cells. If your blood has the protein, you’re Rh positive — the most common Rh factor. If your blood lacks the protein, you’re Rh _____
negative
ISOHEMAGGLUTININS
substances that agglutinate the red blood cells of others of the same species, are also found in humans.
Thus, there are four main blood groups, which differ with respect to two antigens, A and B, in the red blood cells and two isohemagglutinins, anti-A and anti-B, in the serum. T
Isohemagglutinins are of the______class
IgM
Must be IgM due to placenta crossing
Dd
important Rh protin
D= intact
d= amorph
DD
Rh +
Dd
Rh+
dd
Rh -
Rh - makes AB against
Rh + blood
Red cells live
120 days
Do people get blood transfusions for volume?
No
If there is no hemolysis or agglutination, the blood and the recipient are considered _______
“compatible”
Do we give whole blood?
Generally not, because plasma stuffs can react to recipient cells
We usually give just RBCs
is there antibody already on these cells I am
interested in? You rinse off the cells and add antiglobulin to find out.
direct antiglobulin test (DAT)
The direct test detects cells
that were coated with antibody in vivo.
is there unexpected antibody to red cell antigens in the plasma of this potential recipient?
take red cells, add the plasma, rinse the cells, and then add antiglobulin.
If cells agglutinate, must have been AB to them in the plasma, because antiglobulin alone won’t react
indirect antiglobulin test (IAT)
IgG attack the RBC in the fetal circulation; the red blood cells are broken down and the fetus can develop reticulocytosis and anemia.
occurs in Rh(D)+ babies of Rh(D)- mothers
Hemolytic disease of the newborn
A newborn has a high bilirubin. He’s Rh(D)+
and mother is Rh(D)-
Hemolytic disease of the newborn is possible, but there are other causes of:
hyperbilirubinemia
HEMOLYTIC DISEASE OF THE NEWBORN (HDN) Rx
Give mother IgG antibody to Rh(D) Rh-immune globulin
basically causing autoimmune destruction of the AB you do not want
RhoGAM
used to prevent the immunological condition known as Rh disease (or hemolytic disease of newborn).
medicine is a solution of IgG anti-D (anti-RhD) antibodies that take out any fetal RhD-positive erythrocytes which have entered the maternal blood stream from fetal circulation, before maternal immune system can react to them, thus preventing maternal sensitization
RhoGAM
Anti-Rh antibodies are usually IgG (being anti-proteins), and do cross the:
placenta
HETEROPHILE ANTIBODIES
antibodies induced by external antigens
Some cross-react with self-antigens. For example, in rheumatic fever
RhoGAM is a solution of IgG anti-D (anti-RhD) antibodies that take out any fetal RhD-positive erythrocytes which have entered the maternal blood stream from fetal circulation, before maternal immune system can react to them, thus preventing _________
maternal sensitization
