Podcast
Questions and Answers
What characteristic of the S, s, and U antigens impacts their susceptibility to degradation?
What characteristic of the S, s, and U antigens impacts their susceptibility to degradation?
- Their location on the exterior of the cell membrane.
- Their resistance to enzymatic activity.
- Their location deeper on Glycophorin B. (correct)
- Their high concentration on the cell surface.
At which amino acid position(s) do the M and N antigens differ in their sequence?
At which amino acid position(s) do the M and N antigens differ in their sequence?
- Position 5
- Position 29
- Positions 1 and 5 (correct)
- Positions 1 and 29
Which of the following best describes the inheritance and expression of the U antigen in relation to the S and s antigens?
Which of the following best describes the inheritance and expression of the U antigen in relation to the S and s antigens?
- The U antigen is inherited independently of S and s, but its expression is suppressed by their presence.
- The U antigen is always present when S and s are not inherited.
- The U antigen is a universal antigen that is only expressed in the absence of S and s.
- The U antigen's expression is dependent on the inheritance of S and s. (correct)
In the context of MNSs blood group system, what is indicated by the term 'dosage'?
In the context of MNSs blood group system, what is indicated by the term 'dosage'?
Which genetic event results in a cell having no expression of MNSs antigens, leading to the U-phenotype?
Which genetic event results in a cell having no expression of MNSs antigens, leading to the U-phenotype?
What antibodies would react with S+ or s+ red cells?
What antibodies would react with S+ or s+ red cells?
Which antibody is known to demonstrate dosage?
Which antibody is known to demonstrate dosage?
If Anti-M is implicated in HDFN, what characteristic would it most likely possess.
If Anti-M is implicated in HDFN, what characteristic would it most likely possess.
What characteristic is associated with Anti-N when found in renal patients undergoing dialysis?
What characteristic is associated with Anti-N when found in renal patients undergoing dialysis?
What feature characterizes clinically significant Anti-S and Anti-s antibodies regarding temperature?
What feature characterizes clinically significant Anti-S and Anti-s antibodies regarding temperature?
What immediate action should be taken if optimal reactivity of Anti-S or Anti-s is observed between 10-22 deg C?
What immediate action should be taken if optimal reactivity of Anti-S or Anti-s is observed between 10-22 deg C?
For a U-negative patient needing a transfusion, why is finding compatible blood challenging?
For a U-negative patient needing a transfusion, why is finding compatible blood challenging?
Which phenotype has a higher percentage in the white population compared to the black population?
Which phenotype has a higher percentage in the white population compared to the black population?
Which of the following antibodies is least likely to be clinically significant?
Which of the following antibodies is least likely to be clinically significant?
Which antibody is associated with severe HTR and HDFN?
Which antibody is associated with severe HTR and HDFN?
What action is typically required when a patient has anti-U?
What action is typically required when a patient has anti-U?
What can contribute to Anti-N showing reactivity in renal patients?
What can contribute to Anti-N showing reactivity in renal patients?
What should be considered when encountering a patient with Anti-U antibody?
What should be considered when encountering a patient with Anti-U antibody?
Besides red blood cell transfusions, what other situation implicates the need for considering the presence of clinically significant antibodies like Anti-S, Anti-s, or Anti-U?
Besides red blood cell transfusions, what other situation implicates the need for considering the presence of clinically significant antibodies like Anti-S, Anti-s, or Anti-U?
Which antigens are destroyed by enzymes?
Which antigens are destroyed by enzymes?
Flashcards
M&N antigens
M&N antigens
Differ only in their amino acid sequence at positions 1 & 5 (Ser-Gly/Leu-Glu).
S&s antigens
S&s antigens
Differ only in their amino acid sequence at position 29 (Met/Thr).
U antigens
U antigens
Antigens present on all cells and dependent on the S and s antigens.
U-phenotype
U-phenotype
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En(a-) phenotype
En(a-) phenotype
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Mk phenotype (SILENT GENE)
Mk phenotype (SILENT GENE)
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Anti-M
Anti-M
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Anti-N
Anti-N
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Anti-S and Anti-s
Anti-S and Anti-s
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Anti-U
Anti-U
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Study Notes
- S, s, and U antigens are located deeper on Glycophorin B
- This means they are less easily degraded, but still degradable by enzymes
M&N Antigen
- M and N only differ in their amino acid sequence at positions 1 & 5 (Ser-Gly/Leu-Glu)
- S & s only differ in their amino acid sequence at position 29 (Met/Thr)
- All MNSs antigens show dosage
- M and N give a stronger reaction when homozygous (M+N- or M-N+)
- Weaker reactions occur in the heterozygous state (M+N+)
- Antigens are destroyed by enzymes
U Antigens
- Stands for Universal antigens, meaning all individuals have this antigen
- Included in this BGS because the expression of universal antigen is dependent on the S and s
- S+s+ individuals have the U antigen
- If the S and s antigen are absent (S-s-), the U antigen is absent (S-s-U-)
- The U antigen is always present when the S and s are inherited (S+s+U+)
- About 85% of S-s- individuals are U-negative (RARE)
- U-negative cells are only found in the Black population
MNSs Antigen Expression
- It is possible to have no expression of MNSs antigens
- U- phenotype: Deletion of GYPB gene; No U and S & s antigens
- En(a-) phenotype:
- Deletion of GYPA gene; No M & S antigens
- Anti-Ena - En stands for envelope and reacts to various parts of GPA
- Mk phenotype (SILENT GENE): Deletion of GYPA and GYPB genes
Antibodies
Anti-M and Anti-N
- demonstrate dosage
Anti-M
- Naturally occurring
- 50-80% IgG
- Does not bind complement
- Not clinically significant
- Will not react with enzyme treated cells
- If IgG, could be implicated with mild HDFN (rare)
Anti-N
- Very rare, not naturally occurring
- Lesser amount & activity in comparison to Anti-M
- cold reactive
- May be found in renal dialysis patients using equipment sterilized with formalin
- Reacts with Vicia graminea, Bauhinia variegata, Bauhinia purpurea lectins
Anti-S and Anti-s
- Clinically significant
- IgG can bind complement
- This IgG is reactive at 37 deg C and other temps as well (Wide thermal range of activity)
- If optimal reactivity is between 10-22 deg C, perform AHG without incubating @ 37 deg C
- One can proceed to AHG phase without incubation to detect these antibodies
- AHG can still be performed even if the temperature is already at 37 deg C + incubation to detect more of this antibody
- Can cause severe HTR and HDFN
Anti-U
- Will react with S+ or s+ red cells
- Usually occurs on S-s- cells
- Can only give U-negative blood units found in <1% of black population
- Contact rare donor registry
- Can cause severe and fatal HTR and HDFN
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