Rh system - D antigen Flashcards
define immunogenic
ability to cause immune response
what is the Rh system named after
Rhesus monkeys
what is the main concern with anti -D
HDN and TRXN
true or false:
D antigen is the most immunogenic
true
- causes antibody formation in abt 80% of exposure cases
D antigen expression frequencies
white = 80
black = 95
asian = 100
what is the purpose of rhogam
to protect Rh neg moms from immunizing event from baby
how does rhogam work
- shot of transient D antibody to act in place of natural anti-D (mimics actions)
- prevents formation of anti - D in immunizing event
where is the D antigen located
multipass in RBC membrane
what is the role of D antigen
transport of ammonia or Co2
what RBC morphology is seen in Rhnull patients
stomatocytes
how do Rh neg and Rh null differ
- Rh neg = no D antigen but other Rh antigens present
- Rh null = no Rh system antigens
why is polyspecific reagent used to detect D antigen
antigen is pleomorphic - lots of possible changes
Rh negative
D antigen not expressed on red cell at all
- non functioning RHD gene from both parents
weak D / Du
- complete D expression at lower levels
- protein mutation on inside of cell
- do not make antibody against D
describe differences in european, african and asian ancestry in Rh negative inheritance
- european: deletion
- african: missense mutation
- asian: expression at low levels ‘Del’
partial D expression
- protein mutation outside of RBC membrane
- missing parts of D antigen
- Ab formation against missing parts
what is the most common partial D classification
D6
- reagents will not detect (called neg)
define immune stimulated
antibody formation from transfusion or pregnancy
dosage affect
weaker reactivity on cells that only have 1 dose of antigen (D/d)
describe enzyme treated cell enhancement
surface chains cut off = easier to react
can anti - D bind complement
no
- IgG needs multiple pieces to bind compliment
define Rhag
rhesus associated glycoprotein
where is Rhag located
Rhag is a transmembrane protein on RBC by D antigen
list funcitons of Rhag
- regulate cation transport of ammonia of D antigen
- stabilize Rh antigen (protein-protein)
- link lipid layer to ankyrin skeleton
how is Rhag expression related to Rh presentation
Rhag must be present for Rh to be expressed
what chromosome is RhD located
chromosome 1
define Rhesus boxes
flank D gene on chromosome 1
what causes pleomorphic ability of D antigen/heterogeneity
due to nearness of CE gene during transcription
- fold over each other
