D Antigen and Rh Factor Overview

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Questions and Answers

What significantly enhances the reactivity of Rh antibodies?

Incubation with untreated red blood cells

Incubation with enzyme-treated red blood cells (correct)

Presence of complement proteins

Exposure to heat-treated plasma

Which type of antibodies are formed after exposure to red blood cells?

Immunoglobulin M antibodies

Complement antibodies

Autoantibodies

Alloantibodies (correct)

What is the most immunogenic Rh antigen?

Rh(E)

Rh(C)

Rh(c)

Rh(D) (correct)

How long do Rh antibodies typically remain in circulation once formed?

Months to years Signup and view all the answers

What is a common characteristic of individuals who develop one Rh antibody?

They are likely to develop other Rh system antibodies. Signup and view all the answers

Why should Rh(D)-negative recipients receive red blood cells lacking the D antigen?

To prevent hemolytic disease of the fetus and newborn (HDFN) Signup and view all the answers

What is the most common phenotype with the highest number of D antigen sites?

R2R2 phenotype Signup and view all the answers

What condition can result from a CE deletion in Rh(D)-positive individuals?

Absence of CcEe antigens Signup and view all the answers

In what situation might a person's cells appear Rh(D) negative with some anti-D reagents?

Due to weakened D expression Signup and view all the answers

What is the relationship of the RHC gene to the RHD gene concerning D antigen expression?

Inheriting RHC in trans position suppresses D expression Signup and view all the answers

What results from the weakened D condition also known as Du?

Reduced number of D antigens expressed Signup and view all the answers

Which phenotype demonstrates a partial deletion leading to the most D antigen sites?

D– – phenotype Signup and view all the answers

Where is weak D more commonly found?

Among individuals of African ethnicity Signup and view all the answers

What is the main characteristic of weak D?

Quantitative deficiency of the D antigen Signup and view all the answers

How do most partial D individuals react to Rh(D) typing?

Can type as either Rh(D) positive or negative Signup and view all the answers

What testing method is involved in confirming weak D?

Antiglobulin test phase using anti-D reagents Signup and view all the answers

What is a potential consequence for Rh(D)-negative recipients of weak D or partial D blood?

Development of anti-D antibodies Signup and view all the answers

Why is the weak D test not routinely performed on patients?

Weak or partial-D patients should be considered Rh(D)-negative Signup and view all the answers

What characteristic is associated with most common partial D phenotype in individuals of European ethnicity?

Partial D, type VI Signup and view all the answers

What precautions should be taken when transfusing patients with suspected weak or partial D?

Transfusion of Rh(D)-negative RBCs Signup and view all the answers

Why is antisera used in routine patient typing limited in specificity?

To prevent false negatives in weak D testing Signup and view all the answers

Which antigen is considered the most immunogenic among the Rh antigens?

D Signup and view all the answers

What determines the presence of the f antigen on a red blood cell?

Presence of both c and e antigens in cis position Signup and view all the answers

Which statement about the Cw antigen is true?

It can be present with or without C and c antigens. Signup and view all the answers

What is the primary immunoglobulin class of most Rh antibodies?

IgG Signup and view all the answers

At which temperature can Rh antibodies typically be detected after incubation?

37° C Signup and view all the answers

Which antigen is antithetical to the high-incidence antigen MAR?

Cw Signup and view all the answers

What is the immunogenicity order of common Rh antigens from most to least?

D > c > E > C > e Signup and view all the answers

Which antigen is often found on red blood cells expressing the D or C antigen?

G Signup and view all the answers

What is the primary purpose of weak D testing in Rh(D)-negative neonates?

To identify potential alloimmunization risk Signup and view all the answers

What is a hybridoma in the context of clonal antisera?

A hybrid of human and mouse cells producing monoclonal antibodies Signup and view all the answers

Which of the following is true about high-protein anti-D reagents?

They typically contain 22% albumin to enhance agglutination Signup and view all the answers

What differentiates low-protein antisera from high-protein antisera?

Low-protein antisera generally allow for spontaneous agglutination. Signup and view all the answers

What is a major advantage of using clonal reagent anti-D over the historical human source antisera?

It eliminates the risk of contamination from human plasma. Signup and view all the answers

Why was a parallel control important when using high-protein anti-D reagents?

To identify potential false-positive reactions. Signup and view all the answers

Which type of antisera utilizes IgG anti-D that has been chemically modified?

Low-protein antisera Signup and view all the answers

What characteristic of modern monoclonal blend reagents influences the requirement for a parallel control?

They are unlikely to cause spontaneous agglutination. Signup and view all the answers

Study Notes

The D Antigen

The D antigen is the strongest immunogenic antigen in the Rh system.
Rh(D)-negative recipients should only receive Rh(D)-negative blood products.
The D antigen does not express dosage, but Rh(D)-positive individuals express varying numbers of D antigen sites.
R2R2 phenotype (most common) has 16,000 – 33,000 D antigen sites per red blood cell.
D– – (rare) has 100,000–200,000 D antigen sites per red blood cell.

Weakened Expression of D

Some individuals express weak D antigens, which are undetectable by some anti-D reagents.
C antigen in the trans position to D can suppress D antigen expression.
Weak D is a quantitative deficiency in D antigen expression.
Partial D is a qualitative alteration of the D antigen.
Weak D testing is performed on blood donors to label units correctly and on neonates born to Rh(D)-negative mothers to determine alloimmunization risk.
Weak D testing can also resolve discrepancies in Rh typing.

Rh Antisera

Clonal antisera has replaced human source antisera in most cases.
Clonal antisera is usually a blend of monoclonal antibodies to detect more than one epitope of the D antigen.
Anti-D reagents can be IgG, IgM, or a combination.

Other Cell Antigens

The C, c, E, and e antigens are codominant and express dosage.
The C/c antigens differ at position 103, and the E/e antigens differ at position 226.
The G antigen is found on red blood cells that express D or C antigens.
The Cw antigen is found in about 2% of people of European ethnicity.
The f (ce) antigen is expressed when both c and e antigens are present on the red blood cell and the respective genes are in the cis position.
The Ce antigen is expressed when C and e are found in the cis position.

Rh Antibodies

Most Rh antibodies are IgG and react during the antiglobulin phase of testing.
Rh antibodies are red blood cell stimulated.
The Rh(D) antigen is the most immunogenic.
Rh antibodies remain in circulation for long periods.
Rh antibodies do not bind complement but cause extravascular hemolysis.
Individuals who develop one Rh antibody are more likely to develop others.
Some autoantibodies have apparent Rh specificity.

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Description

This quiz explores the D antigen and its significance within the Rh blood group system. It covers aspects such as immunogenicity, weak D expressions, and testing protocols for determining Rh typing. Test your knowledge on these essential concepts in transfusion medicine.