blood Group antigens

Lewis group production is coded by Lewis gene located on chromosome?

19

This antigen act as receptor for Helicobacter

Leb

T/F Leb is present only if an individual has both the Lewis and Secretor gene

T

Which of the following best describes Lewis antibodies?

A. IgG antibodies that react at 37 °C

B. Naturally occurring IgM antibodies that react at cold temperatures

C. Clinically significant antibodies causing severe hemolytic transfusion reactions

D. Antibodies that cannot be neutralized by soluble substances

Answer: B. Naturally occurring IgM antibodies that react at cold temperatures

Lewis antibodies are usually considered clinically insignificant because they:

A. React only with complement

B. Are destroyed by albumin

C. Are neutralized by Lewis substances in secretions such as saliva

D. Are produced only after transfusion

Answer: C. Are neutralized by Lewis substances in secretions such as saliva

The M and N antigens of the MNS blood group system are located on which membrane glycoprotein?

A. Glycophorin B

B. Glycophorin A

C. Band 3 protein

D. Kell glycoprotein

Answer: B. Glycophorin A

• A. Glycophorin B ❌
  Glycophorin B carries S and s antigens, not M and N.

• C. Band 3 protein ❌
  Band 3 is associated with Diego blood group system, not MNS.

• D. Kell glycoprotein ❌
  This carries antigens of the Kell blood group system.

Which amino acids are present in the M antigen?

A. Leucine and glutamic acid

B. Serine and glycine

C. Methionine and threonine

D. Aspartic acid and lysine

✅

Answer: B. Serine and glycine

Explanation:

• B. Serine and glycine ✔
  M antigen has Serine (position 1) and Glycine (position 5).

• A. Leucine and glutamic acid ❌
  These amino acids belong to the N antigen.

• C. Methionine and threonine ❌
  These correspond to S and s antigens.

• D. Aspartic acid and lysine ❌
  These amino acids are not involved in MNS differentiation

Which best describes Anti-M antibodies?

A. IgG antibody reacting at 37°C

B. Naturally occurring IgM antibody that is cold reactive

C. Complement-binding IgA antibody

D. Warm autoantibody

Answer: B. Naturally occurring IgM antibody that is cold reactive

Explanation:

• B. IgM cold antibody ✔
  Anti-M is naturally occurring, IgM, cold reactive, and reacts best at pH 6.5.

Which lectin detects M antigen?

A. Vicia graminea

B. Bauhinia purpurea

C. Iberis amara

D. Dolichos biflorus

Answer: C. Iberis amara

Explanation:

• A. Vicia graminea ❌
  Detects N antigen.

• B. Bauhinia purpurea ❌
  Also associated with N antigen detection.

• D. Dolichos biflorus ❌
  Detects A1 antigen in the ABO system.

Anti-N antibodies may be found in patients who:

A. Receive multiple transfusions

B. Undergo dialysis with formaldehyde-sterilized equipment

C. Have autoimmune diseases

D. Have hemolytic disease of the newborn

Answer: B. Dialysis with formaldehyde sterilization

Which antibodies in the MNS system are usually IgG and react at 37°C?

A. Anti-M and Anti-N

B. Anti-N and Anti-s

C. Anti-M and Anti-S

D. Anti-S and Anti-s

Answer: d. Anti-S and Anti-s

Individuals with S–s– phenotype may produce which antibody?

A. Anti-M

B. Anti-N

C. Anti-U

D. Anti-Lea

C. Anti-U

Which antigen in the P blood group system is known to deteriorate rapidly during storage of red blood cells?

A. P antigen

B. P1 antigen

C. Pk antigen

D. Tja antigen

Answer: B. P1 antigen

Which antibody is described as a naturally occurring IgM cold-reactive saline agglutinin?

A. Anti-P

B. Anti-P1

C. Anti-Tja

D. Autoanti-P

Answer: B. Anti-P1

Anti-P1 antibodies can be neutralized using which substance?

A. Albumin solution

B. Hydatid cyst fluid

C. Saliva from secretors

D. Cord serum

Answer: B. Hydatid cyst fluid

Explanation

• B. Hydatid cyst fluid ✔
  Hydatid cyst fluid from Echinococcus granulosus can neutralize Anti-P1 antibodies.

• A. Albumin ❌
  Albumin enhances antibody reactions but does not neutralize Anti-P1.

• C. Saliva ❌
  Saliva neutralizes Lewis antibodies, not P1 antibodies.

• D. Cord serum ❌
  Used in some antibody identification but not for Anti-P1 neutralization.

Anti-Tja (Anti-PP1Pk) was first described in the serum of a patient with:

A. Gastric adenocarcinoma

B. Leukemia

C. Liver cirrhosis

D. Multiple myeloma

A. Gastric adenocarcinoma

Anti-Tja is clinically important because it is associated with:

A. Hemolytic transfusion reactions only

B. Increased incidence of spontaneous abortions

C. Severe hemolytic disease of the newborn

D. Autoimmune hemolytic anemia

Answer: B. Increased incidence of spontaneous abortions

Explanation

• A. Hemolytic transfusion reactions only ❌
  It can cause reactions but pregnancy complications are the key association.

• C. Severe HDFN ❌
  The main concern is spontaneous abortion, not classic HDFN.

• D. Autoimmune hemolytic anemia ❌
  Anti-Tja is alloimmune, not autoimmune

Which antibody is associated with paroxysmal cold hemoglobinuria (PCH)?

A. Anti-P1

B. Anti-Tja

C. Autoanti-P

D. Anti-Pk

Answer: C. Autoanti-P

The Donath–Landsteiner test is used to demonstrate:

A. Anti-P1

B. Anti-Tja

C. Autoanti-P

D. Anti-Lea

Answer: C. Autoanti-P

The P antigen serves as a receptor for which pathogen?

A. HIV

B. Influenza virus

C. Parvovirus B19

D. Epstein–Barr virus

Answer: C. Parvovirus B19

Explanation

• A. HIV ❌
  Uses CD4 receptors, not P antigen.

• B. Influenza ❌
  Uses sialic acid receptors.

• D. Epstein–Barr virus ❌
  Uses CD21 receptor on B cells.

Which statement correctly describes the I Blood Group System?

A. I antigen is abundant in newborns

B. i antigen predominates in adults

C. I antigen predominates in adults

D. I antigen is absent in individuals with Bombay phenotype

Answer: C. I antigen predominates in adults

Explanation

• C. I antigen predominates in adults ✔
  Adults mainly express I antigen, while infants are rich in in i.

• B. i antigen predominates in adults ❌
  This is the opposite of the normal developmental switch.

• D. I antigen absent in Bombay phenotype ❌
  Individuals with Bombay phenotype can have increased I activity, not absence

Pathogenic autoanti-I antibodies are commonly associated with which infection?

A. Epstein–Barr virus infection

B. Mycoplasma pneumoniae infection

C. Cytomegalovirus infection

D. Influenza infection

Answer: B. Mycoplasma pneumoniae infection

Explanation

• B. Mycoplasma pneumoniae ✔
  Autoanti-I is associated with cold agglutinin syndrome, especially in Mycoplasma pneumoniae infections.

• A. Epstein–Barr virus ❌
  This is associated with Anti-i antibodies in infectious mononucleosis, not Anti-I.

Which statement about the Kell Blood Group System is correct?

A. Kell antigens are encoded on chromosome 1

B. Kell is second only to RhD in immunogenicity

C. Anti-K antibodies are usually IgM

D. Anti-K rarely causes hemolytic disease of the newborn

Answer: B. Kell is second only to RhD in immunogenicity

Explanation

• B. Second to RhD ✔
  Kell is highly immunogenic, second only to RhD.

• A. Chromosome 1 ❌
  Kell gene (KEL) is located on chromosome 7.

• C. IgM ❌
  Anti-K antibodies are usually IgG.

• D. Rarely causes HDFN ❌
  Anti-K can cause severe hemolytic disease of the newborn.

The McLeod phenotype is characterized by:

A. Autosomal dominant inheritance

B. Absence of all Rh antigens

C. X-linked inheritance affecting mainly males

D. Increased Kell antigen expression

Answer: C. X-linked inheritance affecting mainly males

Which phenotype provides resistance to Plasmodium vivax malaria?

A. Fy(a+b+)

B. Fy(a+b−)

C. Fy(a−b+)

D. Fy(a−b−)

Answer: D. Fy(a−b−)

Which statement about Fya and Fyb antigens is correct?

A. Enhanced by enzyme treatment

B. Destroyed by enzyme treatment

C. Resistant to enzyme treatment

D. Not affected by storage condition

Answer: B. Destroyed by enzyme treatment

Explanation

• B. Destroyed ✔
  Fya and Fyb are destroyed by enzymes like ficin or papain.

• A. Enhanced ❌
  This is characteristic of Kidd antibodies, not Duffy.

• C. Resistant ❌
  They are actually very enzyme sensitive.

• D. Not affected by storage ❌
  They do not store well in saline suspension.

Why are Kidd Blood Group System antibodies notorious in transfusion medicine?

A. They cause immediate hemolysis only

B. They are easily detected in screening

C. They are associated with delayed hemolytic transfusion reactions

D. They are always IgM, leading to acute hemolytic reactions.

Answer: C. Delayed hemolytic transfusion reactions

• They are usually IgG warm antibodies.

Which test characteristic is associated with Jk(a-b-) phenotype RBCs?

A. Hemolyze rapidly in saline

B. Resist lysis in 2M urea

C. Destroyed by enzyme treatment

D. Show weak expression of ABO antigens

Answer: B. Resist lysis in 2M urea

Explanation

• B. Resist lysis ✔
  Kidd-null RBCs resist hemolysis in 2M urea, which is used for identification.

The Diego Blood Group System antigens are located on which RBC membrane protein?

A. Glycophorin A

B. Band 3 (anion exchange protein)

C. Aquaporin-1

D. Complement receptor 1

Answer: B. Band 3 (anion exchange protein)

Explanation

• B. Band 3 ✔
  Diego antigens are found on AE-1 (band 3), which exchanges bicarbonate and chloride ions.

• A. Glycophorin A ❌
  Associated with the MNS system (M and N antigens).

• C. Aquaporin-1 ❌
  This is the Colton blood group system location.

• D. Complement receptor 1 ❌
  This corresponds to the Knops system.

Which blood group system is located on acetylcholinesterase?

A. Cartwright

B. Scianna

C. Colton

D. Cromer

Answer: A. Cartwright

Explanation

• A. Cartwright ✔
  Antigens of the Cartwright Blood Group System are located on acetylcholinesterase.

• B. Scianna ❌
  Located on ERMAP adhesion protein.

The Xg Blood Group System has which genetic characteristic?

A. Located on chromosome 7

B. Located on chromosome 19

C. Located on the short arm of the X chromosome

D. Located on chromosome 6

Answer: C. Short arm of the X chromosome

Antigens of the Scianna Blood Group System are expressed on which protein?

A. ERMAP adhesion protein

B. Glycophorin B

C. Aquaporin-1

D. CD44

Answer: A. ERMAP adhesion protein

Explanation

• A. ERMAP ✔
  Scianna antigens are expressed on erythroid membrane-associated protein (ERMAP).

• B. Glycophorin B ❌
  Associated with S and s antigens of MNS system.

• C. Aquaporin-1 ❌
  Associated with Colton system.

• D. CD44 ❌
  Associated with the Indian blood group system.

Which blood group system is associated with aquaporin-1 water channel protein?

A. Colton

B. Cromer

C. Knops

D. Gerbich

Answer: A. Colton

Explanation

• A. Colton ✔
  The Colton Blood Group System antigens are found on aquaporin-1, a water transport channel.

• B. Cromer ❌
  Located on DAF (CD55).

• C. Knops ❌
  Located on CR1 (CD35).

• D. Gerbich ❌
  Located on glycophorin C and D.

The Gerbich Blood Group System antigens are associated with which RBC membrane proteins?

A. Glycophorin A

B. Glycophorin C and D

C. Glycophorin B

D. Band 3

Answer: B. Glycophorin C and D

Explanation

B. Glycophorin C and D ✔
Gerbich antigens are located on glycophorin C and D, linked with band 4.1 protein.

Which blood group system is located on decay-accelerating factor (CD55)?

A. Cromer

B. Knops

C. Dombrock

D. Chido/Rodgers

Answer: A. Cromer

The Knops Blood Group System antigens are located on which receptor?

A. CD44

B. CR1 (CD35)

C. CD55

D. CD108

Answer: B. CR1 (CD35)

Which blood group system is associated with CD44 glycoprotein?

A. Indian

B. Scianna

C. Gerbich

D. Knops

Answer: A. Indian

Which blood group system is associated with complement C4 components?

A. Chido/Rodgers

B. Knops

C. Cromer

D. Colton

Answer: A. Chido/Rodgers