MLS 418 - LAB/LEC
IMMUNOHEMATOLOGY
Rh Blood Grouping
PROF. JENNIE ONG
Rh Antigens
Biochemistry
● Nonglycosylated proteins.
○ Means that there are no
carbohydrates attached to the protein.
○ As you can see in the photo, this is the
RhCE antigen, the RhD,and the Rh
associated glycoprotein.
○ Among the three, only the RhAG
antigen is glycosylated or has a
carbohydrate attached to it.
●Transmembrane proteins.
● RHD and RHCE are remarkably similar (416
AA; traverse 12 times)
○ Both are composed of 416 amino
acids that traverse the cell membrane
12 times, same with RhD and RhAG.
● Differ by only 32 to 35 amino acids
RhCE on the other hand, has this amino acid position:
●AA position 103: C or c expression
○ will determine if the antigen is an
uppercase C antigen positive, or a
lowercase c positive antigen
●AA position 226: E or e.
○ will determine if the antigen is an
uppercase E positive or a lowercase e
antigen positive.
● These antigens RhCE, RhD, and RhAG are
exclusively seen in RBCs meaning they
cannot be seen in other cells.
● Only small loops of Rh proteins are exposed
on the surface of the RBC and provide the
conformational requirements for many
serological differences between the Rh blood
types.
● As they are transmembrane it is not surprising
they play a role in maintaining the structural
integrity of red blood cells.
● Based on their structure, it appears they may
be also transporters.
● Westhoff and colleagues showed they may
have a role in transporting ammonia. An
alternative hypothesis is that they may also be
carbon dioxide transporters, so these antigens
may have other functions.
Antigen Characteristics
● Remember that, Rh antigens are proteins
integral to the RBC membrane passing
through the RBC wall 12 times
● Found only on RBCs, and are not soluble or
expressed on other cells.
● The Rh antigens are well-developed at birth.
○ such can cause hemolytic disease of
the the fetus and newborn or HDFN
● Immunogenic
○ exposure to foreign antigens through
transfusion or pregnancy can cause
an immune response to the production
of corresponding antibodies.
● 5 common Rh antigens: D, C, E, c, e
○ their specific corresponding antibodies
account for the majority of problems
due to Rh antibodies
● The D antigen does not have an allele, but C
and c are alleles, and E is allelic to e.
D Antigen
● Rh antigens are highly Immunogenic
● Among the antigens, the D antigen is the
most potent.
○ This is not surprising given that most
Rh-negative individuals lack the entire
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