exam 2 - ab detection Flashcards Preview

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Flashcards in exam 2 - ab detection Deck (25):
1

(T/F) the aim of antibody screening is to detect both clinically significant and INsignificant antibodies

false

Detect ‘all’ clinically significant antibodies only

2

_____ cells used in ab screening

type O

3

which of the ff is false about ab screening?
a. patient's medical history is impt
b. it is part of the pre-transfusion testing
c. patient RBCs are used/tested
d. always include the antiglobulin (AHG) test

C

test done on patient plasma

4

(T/F) Results of a positive antibody screen gives the first clue that starts the antibody identification process

true

5

(T/F) antibodies to low incidence antigens can be detected with screen test

false

the ag may not be present on the screening cells used

6

(T/F) if the antibody titer is below detectable level the antibody screen will be negative

true

7

(T/F) the 3-and-3 rule will ensure that 95% of the time the identification will be correct

true

8

(T/F) if an antibody for Fya has been detected, the patient RBC phenotype must be tested with an anti-Fya reagent to confirm the presence of the Fya antigen in their cells

false

process is right but the test should be non reactive (no Fya antigen present in patient RBCs)

9

(T/F) patient with DAT pos results or had recent transfusions can be screened for antibodies

false

this is a typing exemption

10

which of the ff methods is not used in ab screening?
a. incubation
b. tube testing
c. solid phase testing
d. gel technique

A

this is part of some methods but by itself is not used in screening

11

_____ occurs when cell typing produces a mixed reaction because of the presence of two cell population

mixed field agglutination

12

(T/F) A positive antibody screen and a negative auto control indicate that an auto-ab is present

false

this is indicative for alloantibody

13

which of the ff is false?
a. a positive auto control indicates presence of autoantibodies
b. more than one positive screening sample can mean that patient has multiple ab or autoantibody
c. a single ab specificity is suspected if screen cell test have reactions of diff strength at diff phases
d. a rouleaux can give false pos screening result

C

single ab = rxn at same phase and strength

multiple = rxn diff phase and strength

14

(T/F) Lu antibodies are associated with mixed field agglutination

true

15

which of the ff is NOT true about the strength of reaction in ab panel?
a. strength of rxn can indicate the significance of ab
b. can indicate the amount of ab in the rxn
c. can indicate the presence of more than one ab
d. stronger reaction can indicate dosage

A

16

(T/F) a heterozygous cell react more strongly than homozygous cells

false
homozygous react stronger

hetero = single dose
homozyg = double dose

17

(T/F) Cells that react at multiple phases may also be a sign of an antibody showing dosage

true

homozygous cells reacting at an earlier phase than the heterozygous cells

18

(T/F) clinically significant ab usually react at the IS phase

false

these are IgM, usually insignificant

19

which of the ff is false?
a. Antibodies to low-frequency antigens are uncommon and it may not be necessary to rule them out
b. additional test should be done on commonly encountered ag that are not ruled out
c. a negative auto ctrl rxn shows that identification results are correct
d. presence of anti-K will show reaction with K- cells

D

duh

no ag= no rxn

20

(T/F) if if anti-K and anti-E are both suspected, K-E- cells will react negatively, K+E- cells will react negatively and K-E+ cells will react negatively

false

K-E- = neg
K+E- = pos (anti-K will react with K+)
K-E+ = pos (anti-E will react with E+)

21

____ antibodies that are formed by an R1R1, K-negative, Fy(a-b+), Jk(a+b+), M+N+S+s+ patient

anti-c, anti-E, anti-K, or anti-Fya

22

(T/F) DAT positive cells can give a false-positive reaction

true

The coating antibody blocks the antigens sites, preventing the typing serum from reacting

23

(T/F) in recently transfused patients, donor cells that stimulated antibody formation react with the typing serum showing mixed field agglutination while patient’s autologous
cells do not react

true

24

(T/F) enzymes modify the RBC surface by removing sialic
acid residues and by denaturing or removing glycoproteins, destroy certain antigens and enhance expression
of others

true

25

(T/F) exclusion technique can also be done on panel cells with enzymes

false

cant do this coz some ag are destroyed. must compare with another panel with same cells that are untreated