Lecture 5: Rh System-D Flashcards
Outside of the ABO system, the D antigen is the most __________ antigen… because Rh alloimmunization is IgG mediated, transfusion reactions are primarily extravascular. The patient may have a fever, jaundice, icteric sclera, dark urine or a drop in hemoglobin.
immunogenic
What is the Rh interpretation of this:
Anti-A: 0
Anti-B: 0
Anti-A, B/ Anti-D: 0, 4+
A1 cell: 4+
B cell: 4+
O pos
In 1937: Guinea pigs and rabbits injected with Rhesus monkey RBCs because these were common animals for experimentation. In 1940: Once the antibody was isolated from the rabbits, the antibody was agglutinated with human cells.
Antibody formed that reacted with 85% of human RBCs. The antigen called the Rhesus or ____ factor
Rh
In 1963, Rabbit source anti-Rh reactivity did _____ match human source anti-Rh.
Rabbit source anti-Rh was positive on all newborn cells even those found to be negative for human anti-Rh. Rabbit source anti-Rh was renamed LW in honor of Landsteiner and Weiner (who did not like that it was named this.)
NOT
The Characteristics of LW system: LW antigens are more abundant on Rh _______ than Rh negative red cells.
positive
-Antigens can be depressed in Lymphoma, pregnancy
The Characteristics of LW system: Gene is on Chromosome ___ and belongs to ICAM family responsible for erythrocyte adhesion to macrophages for expulsion of their nucleus during maturation.
19
-Two alleles: LWa (high incidence) LWb (low incidence
-LWb more common in Finns
Utilize the history of this antigen system to differentiate between Rh blood system, RHAG and LW blood system.
RH System:
Anti-D human
-Highly immunogenic
-causes HDFN and TRXN
Intrinsic protein to human RBC
-Resistent to DTT and Enzymes
D antigen is present or absent from cell with little structural change.
Name the antithetical antigen pairs in the Rh system and their relative population frequencies in Caucasian, Black and Asian populations of the United States.
- Most polymorphic system of the human antigens
-second most clinically significant antigen
–>Transfusion reactions are hemolytic
–> HDFN #1 cause
-Most “immunogenic” antigen - exposure causes antibody formation estimated 80% of the time in healthy individuals
- Variable frequency based on race:
–> Caucasian= 80%
–> Black = 95%
–> Asian = ~100%
Autosomal Dominant inheritance
No alleles: Antigen is either present or not
–> Many mutants of D have been found, especially in the Black community.
Before 1960s lots of baby deaths due to maternal incompatibility with infant (HDFN). Rhogam is a commercial made low dose anti-D shot. Prevents real (allo) anti-D from _____ in mothers.
forming
What is the red cell shape of Rhnull
Stomatocytes
Antigen is an _______ protein to the RBC membrane.
-Non Glycosylated
-Small variable portions on outside of the membrane
-ONLY on RBCs (not on other cells)
intrinsic
-Begin developing on RBCs as early as 16 weeks from conception, well developed at birth.
-Role: Membrane structure
–> Transport ammonia or CO2 (cations)
Rh postive - D antigen is _______
expressed
Rh postive - D antigen is _______
not expressed
“Weak D” Du - Antigen expression is _____ that it requires _________ (AHG phase testing ) for detection
low, enhancement
“Partial D” - Antigen expression is _____ depending on the reagent.
variable
Rh postive - D antigen is expressed in 10000-200000 antigens on the red cell. Antigen is so pleomorphic that FDA requires serological reagents to be _________. Autosomal Dominant inheritance of at least 1 RHD gene from a parent.
Reagent anti-sera reacts at ___________ with patient cells
polyspecific, room temperature
Rh negative - D antigen not expressed on Red cell at all. Autosomal recessive inheritance of a non functioning RHD gene from _____ parents. The gene differs based on ancestry.
both
European ancestry - ________ of RHD gene
deletion
You don’t have it
African ancestry - RHD gene with _____ mutations that does not produce the D protein.
missense
(cause a mutation)
Asian ancestry - “Del) mutant RHD gene that results in expression of the antigen that is so ____ serologically that it can only be detected through __________/elution. 10-30%
low, adsorption
( you have to do extensive testing to even find it)
“Weak D” Du- Previously thought to be a new allele but no anti-Du is ever made.
Complete D expression but in _____ quantity.
Mutations occur in transmembrane portion of protein, not the part on outside.
DO NOT make anti-D
lower
Reagent antisera reacts <2+ with patient cells at room temperature
DO NOT make anti-D
“Partial D” is far less _______ than Weak D in Caucasians more in ________.
common, blacks
Parts of D are missing on outside of cell due to mutations in RHD gene
CAN make anti-D to the missing portion - Reagent antisera might react positive or negative with patient red cells.
Using the antigens structure on the cell, explain the serological and immunological difference between a patient who is “weak D” and “partial D”
Who can make anti-D?
a) Del
b) Du
c) D negative
d) D partial
C and D
All or part of the antigen is missing from the patient cell. If the patient sees the normal antigen they will view it as foreign. Potentially stimulating antibody production.
