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Flashcards in BB - Day 2 Deck (47)
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1
Q

Define “naturally occurring” antibodies. What two types of antibodies are considered naturally occurring?

A

Targets antigens on RBCs due to similarity to a naturally occurring target in nature
-unknown mechanism, possibly gut bacteria

anti-A and anti-B

2
Q

ABO - which phenotype is the rarest?

A

AB

3
Q

Naturally occurring antibodies - can they cross the placenta? Why or why not?

A

No - predominantly IgM

-except anti-A,B, which is IgG

4
Q

ABO - which phenotype is the universal RBC donor? Universal plasma donor? Universal recipient?

A

RBC donor = O negative
-can only take other O blood

Plasma donor = AB
-no antibodies against A or B antigens

Recipient = AB

5
Q

Can newborns be forward typed and back typed?

A

Forward = yes

Back = no, only maternal antibodies present at birth
-wait >6 months

6
Q

At what temperature do ABO antibodies react best?

A

Room temperature or colder

7
Q

The immune form of ABO antibodies are produced during (2)…

A

Transfusions

Pregnancy

-these events expose patients to foreign blood cells

8
Q

Anti-A,B antibody is produced only by this ABO phenotype

A

O

9
Q

Which ABO antibody(ies) can frequently cross the placenta? Why?

A

Mostly anti-A,B since they are predominantly IgG

10
Q

A and B antigens are composed of… Their precursor is…

A

Carbohydrates

H antigen

11
Q

Which gene codes for H antigen?

A

H gene

  • independent of ABO genes
  • H is dominant; one copy can make H antigen (Hh)
12
Q

A person that’s hh phenotype can’t make what antigens… Another name for the hh phenotype

A

H antigen, A antigen, and B antigen
-H antigen is a precursor to A and B; cannot make H = cannot make A or B

Bombay

13
Q

A person’s H precursor levels are highest in this ABO phenotype. Why?

A

O

No A or B antigens on O cells, so a lot of residual H

14
Q

A Bombay patient should receive a blood transfusion from another person with this blood type… Why?

A

Bombay

Bombay patients make anti-H against all other ABO groups

  • anti-H is naturally occurring
  • forward = A and B negative
  • reverse = anti-A1, anti-B, anti-O positive
15
Q

Besides RBCs, ABO antigens are also found on… What is this significance?

A

Endothelium, kidney, heart, bowel, pancreas, lungs

Can cause extravascular hemolysis

16
Q

A person is considered a secretor when they can secrete these antigens in all bodily secretions… The secretor system involves which two blood group systems?

A

A, B, H

ABO and Lewis

17
Q

What percent of the US population are secretors?

A

80%

18
Q

To be a secretor, a person must have one of these genotypes… People that are non-secretors have this genotype…

A

SeSe or Sese (dominant phenotype)

sese

19
Q

A1 vs A2 - which is more common?

A

A1 = “normal” A

20
Q

A1 reacts with which anti-A antibodies? A2 reacts with which anti-A antibodies?

A

A1 = anti-A, anti-A1
-A1 cells have A and A1 antigens

A2 = anti-A only
-A2 cells have A antigens only

21
Q

Dolichos biflorus will agglutinate this cell

A

A1 cells

anti-A1 lectin

22
Q

A1 and A2 can be distinguished via forward or reverse typing?

A

Reverse typing only

23
Q

Ulex europaeus will agglutinate A1 or A2 cells? Why?

A

A2 cells
-U. europaeus = anti-H lectin

A2 has more precursor H than A1
-incomplete conversion to A antigen = more remaining precursor H

24
Q

anti-H antibody - what class of antibodies?

A

IgM - reacts best under room temp, can bind complement

-similar to other ABO antibodies

25
Q

What blood should be given to A2 patients?

A

A2 or O

-A2 patients make anti-B and anti-A1 antibodies, but not anti-A antibodies

26
Q

anti-H antibody reacts strongest and weakest with these ABO phenotypes

A

Strongest = O (high precursor H)

Weakest = A1B (low precursor H)

-suspect anti-H antibody if O cells are reactive but A cells are not

27
Q

General rule in the lab - should we drop cells first or solution first?

A

Drop solution first, cells second

  • so you know you’ve already added it
  • so you don’t contaminate reagents
28
Q

Why are A1 cells normally used for reverse typing?

A

A1 cells contain high number of A antigens

29
Q

If there’s a discrepancy and the reverse typing does not match the forward typing what can we do with our test tubes?

A

Let samples sit for 15 mins at room temperature, then re-spin tubes
-weak positive for reverse typing not good enough

30
Q

Depressed antibody production affects forward or reverse typing?

A

Reverse

  • seen in newborns, elderly, leukemias
  • lower or nonexistent antibody production
31
Q

What is the “acquired B” phenomena? How is it treated?

A

Bacterial enzymes convert A antigen to B antigen, so patient’s anti-B antibodies attack cells

Acidify patient’s sera

32
Q

Where can one find Wharton’s jelly?

A

On baby’s cord blood only

  • mucopolysaccharide that sticks to RBCs
  • need multiple washing to get rid of
33
Q

A2 patients show a reverse typing that looks like… Why?

A

O

A2 patient has anti-B and some anti-A1 antibodies naturally because A2 cells have A antigens but no A1 antigens
-A1 patients have both A antigen and A1 antigen

34
Q

What is the name of the A antigen sugar? What is the name of the B antigen sugar?

A

N-acetylgalactosamine

D-galactose

35
Q

HDFN is caused primarily by the antigen group

A

Rh

36
Q

Rh - what are the 5 major antigens?

A

D, C, c, E, e

37
Q

What does little ‘d’ signify in the Rh group?

A

Lack of D antigen

-little ‘d’ is NOT an antigen

38
Q

Are homozygous or heterozygous antigens stronger?

A

Homozygous = more binding sites

39
Q

What should we do if our anti-D and Rh control tubes are both negative?

A

Do a weak D test

-15 min at 37C, 3x wash, AHG

40
Q

Weak D is caused by (3)…

A

Genetics - person makes fewer D antigen

C Trans - allele carrying D trans to allele carry C
-Dce/dCe

Partial D (mosaic D) - missing piece of the antigen

41
Q

Rh antibodies are what class of immunoglobulins? When are they produced?

A

IgG

After exposure due to transfusion or pregnancy
-not naturally occurring

42
Q

What temperature do Rh antibodies react optimally?

A

37C

  • anti-D = IgG, reacts best at 37C
  • that’s why we heat 37C for 15 min in weak D test
43
Q

Do Rh antibodies cause intravascular or extravascular hemolysis? Why?

A

Extravascular only

Rh CANNOT bind complement

44
Q

Can Rh antibodies cross the placenta? Why?

A

Yes

They are IgG

45
Q

Rh-negative mothers are automatically given ___ at the 28th week of pregnancy to prevent ___

A

RhIg (RhoGAM) - an anti-D antibody

Sensitization to Rh-positive baby, making anti-D antibodies

  • can make IgGs that cross placenta and attack baby’s cells, causing extravascular hemolysis (HDFN)
  • given even if we don’t know baby’s Rh status yet
46
Q

Is Cw expressed on big C or little c?

A

Both

  • allele on C/c locus
  • low frequency antigen
47
Q

Which 2 Weiner phenotypes are the rarest?

A

Rz and r^y