Rh system - D antigen

Question 1

define immunogenic

Answer 1

ability to cause immune response

Question 2

what is the Rh system named after

Answer 2

Rhesus monkeys

Question 3

what is the main concern with anti -D

Answer 3

HDN and TRXN

Question 4

true or false:
D antigen is the most immunogenic

Answer 4

true
- causes antibody formation in abt 80% of exposure cases

Question 5

D antigen expression frequencies

Answer 5

white = 80
black = 95
asian = 100

Question 6

what is the purpose of rhogam

Answer 6

to protect Rh neg moms from immunizing event from baby

Question 7

how does rhogam work

Answer 7

• shot of transient D antibody to act in place of natural anti-D (mimics actions)
• prevents formation of anti - D in immunizing event

Question 8

where is the D antigen located

Answer 8

multipass in RBC membrane

Question 9

what is the role of D antigen

Answer 9

transport of ammonia or Co2

Question 10

what RBC morphology is seen in Rhnull patients

Answer 10

stomatocytes

Question 11

how do Rh neg and Rh null differ

Answer 11

• Rh neg = no D antigen but other Rh antigens present
• Rh null = no Rh system antigens

Question 12

why is polyspecific reagent used to detect D antigen

Answer 12

antigen is pleomorphic - lots of possible changes

Question 13

Rh negative

Answer 13

D antigen not expressed on red cell at all
- non functioning RHD gene from both parents

Question 14

weak D / Du

Answer 14

• complete D expression at lower levels
• protein mutation on inside of cell
• do not make antibody against D

Question 15

describe differences in european, african and asian ancestry in Rh negative inheritance

Answer 15

• european: deletion
• african: missense mutation
• asian: expression at low levels ‘Del’

Question 16

partial D expression

Answer 16

• protein mutation outside of RBC membrane
• missing parts of D antigen
• Ab formation against missing parts

Question 17

what is the most common partial D classification

Answer 17

D6
- reagents will not detect (called neg)

Question 18

define immune stimulated

Answer 18

antibody formation from transfusion or pregnancy

Question 19

dosage affect

Answer 19

weaker reactivity on cells that only have 1 dose of antigen (D/d)

Question 20

describe enzyme treated cell enhancement

Answer 20

surface chains cut off = easier to react

Question 21

can anti - D bind complement

Answer 21

no
- IgG needs multiple pieces to bind compliment

Question 22

define Rhag

Answer 22

rhesus associated glycoprotein

Question 23

where is Rhag located

Answer 23

Rhag is a transmembrane protein on RBC by D antigen

Question 24

list funcitons of Rhag

Answer 24

• regulate cation transport of ammonia of D antigen
• stabilize Rh antigen (protein-protein)
• link lipid layer to ankyrin skeleton

Question 25

how is Rhag expression related to Rh presentation

Answer 25

Rhag must be present for Rh to be expressed

Question 26

what chromosome is RhD located

Answer 26

chromosome 1

Question 27

define Rhesus boxes

Answer 27

flank D gene on chromosome 1

Question 28

what causes pleomorphic ability of D antigen/heterogeneity

Answer 28

due to nearness of CE gene during transcription
- fold over each other