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44 Cards in this Set
- Front
- Back
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What is the H antigen?
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Precursor found on all human RBCs
This is the foundation upon which A and B Ags are made |
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What is added onto the H Ag to make it an A Ag?
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N-acetyl-galactosamine
NOTE: this is added onto a D-galactose residue |
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What is added to the "precursor substance" to complete H Ag synthesis?
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L-fucose
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What is added onto the H Ag to make it a B Ag?
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D-galactose
NOTE: this is added onto a D-galactose residue |
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What is H Ag synthesis controlled by?
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A dominant gene, H
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What phenotype (blood type) has the most H Ag?
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Type O
This is because the O allele doesn't direct any modification of the H Ag |
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The majority of Native Americans are what blood type?
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Type O
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How are blood types distributed amongst blacks and orientals?
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~50% Type O
~25% each of Type A and B <5% of Type AB |
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How are blood types distibuted amongst whites?
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~45% Type O
~40% Type A ~10% Type B ~5% Type AB |
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What Abs do humans produce by 6 months of age?
(w/ regards to blood types) |
Abs against those antigens which they lack
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By how old, do humans produce blood type Abs?
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6 months of age
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Blood type Abs in Type A and Type B people are of what class?
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Predominantly IgM
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Blood type Abs in Type O people are of what class?
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Mixture of IgG and IgM
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In incompatible tranfusions, what does the mortality rate depend on?
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Amount of blood received
25% for over 500 ml 44% for over 1000 ml |
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What type of Abs are used in the blood bank to phenotype samples?
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IgG
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What is forward grouping?
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Phenotype of the patient's RBCs
Determined by reacting anti-A and B Abs against patient CELLS |
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What is reverse grouping?
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Testing pt serum for Abs
A and B RBCs are reacted against patient's SERUM |
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What is the D Ag?
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Epitope that qualified people as being Rh+
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How is the D Ag inherited?
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Autosomal dominant
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What % of people are D positive?
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~85%
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When are Abs against D formed?
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Only upon exposure
NOTE: this is different than other blood type Abs (Remember, others are formed naturally by 6 months of age) |
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How are blood samples D Ag typed?
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Using forward grouping
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What is the Antibody screen?
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Test to detect common Abs in patient's SERUM
Type O cells w/ the common Ags are reacted w/ patient's SERUM Anti-human globulin is added If Abs are present in pt. serum, agglutination will occur |
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What is the Crossmatch?
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Identical to the Ab screen, except that cells are from unit being transfused
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In what circumstance can whole blood be transfused?
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ONLY if donor and recipient are identical ABO type
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Why can you not transfuse type O whole blood into an A or B recipient?
(large volume transfer) |
Evenutally, anti-A or anti-B Abs in Type O plasma will react
NOTE: a SMALL quantity of incompatible plasma is not harmful |
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What type is the universal recipient?
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AB
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What type is the universal donor?
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O
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How many D positive transfusions can a D negative person receive?
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One, before they develop Abs
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Who can Type O be transferred to?
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Only to Type O pts.
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Who can Type AB plasma be transferred to?
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To anyone
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Are there type restrictions on platelet transfusions?
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NO
NOTE: a D neg pt. CAN be immunized by a platelet tranfusion (due to the few red cells present in platelet concentrate) |
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Abs are usually formed to which Ags on platelets?
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HLA Ags
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What is leukocyte reduction?
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Filtering to remove 3 to 4 logs of WBCs
Reduces alloimmunization to HLA Ags in platelet transfusions Works ~90% of time |
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What are the 3 indications for use of leukocyte reduced products?
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Prevent febrile, non-hemolytic transfusion rxns.
Prevent transmission of CMV Prevent alloimmunization to platelets |
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What is a febrile NON-hemolytic transufsion reaction (FNHTR)?
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Temp elevation of one degree C or more within 2 hrs of transfusion
Fever is caused by cytokines from leukocytes and HLA Abs |
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How are FNHTRs treated?
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Acetaminophen and observation
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What is urticaria?
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Hives
In blood bank, due to type I hypersensitivity to transfused unit |
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Acute INTRAvascular hemolytic transfusion reaction
What is it almost always due to? |
ABO incompatibility
NOTE: this is VERY serious Can cause hypotension --> renal failure, DIC |
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What type of Abs are involved in ACUTE INTRAvascular HTR?
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IgM
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What type of Abs are involved in DELAYED EXTRAvascular HTR?
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IgG
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What is Delayed EXTRAvascular HTR caused by?
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Abs OTHER THAN ABO
These were at too low a titer to be detected by the Ab screen An anamnestic response is elicited |
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In Delayed EXTRAvascular HTR, what are transfused RBCs removed by?
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Splenic macrophages
Occasionally, complement will be activated (this is more severe) |
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In Acute INTRAvascular HTR, what are transfused RBCs removed by?
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Complement
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