Lecture 4 - Rh Blood Group PDF

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Lecture 4 - RH BLOOD GROUP SYSTEM02/02/NOX | HIRAYARH BLOOD GROUP SYSTE M Rh Genes – RhD (produces D antigen) – its presence indicates RH (+) and RhCE (can produce C or E with 4 different alleles) Chromosome 1  Composed of 50 antigenic specificities  ISBT # 004History  1939 – ABO was the only si...

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Lecture 4 - RH BLOOD GROUP SYSTEM 02/02/22

RH BLOOD GROUP SYSTEM  Rh Genes – RhD (produces D antigen) – its presence indicates RH (+) and RhCE (can produce C or E with 4 different alleles) Chromosome 1  Composed of 50 antigenic specificities  ISBT # 004

History  1939 – ABO was the only significant blood group  Levine and Stetson – they described hemolytic transfusion reaction in a newly delivered baby from a pregnant mother – they have isolated an antibody that is reactive in 37-degree C  1940 (Landsteiner and Weiner) - reported on an antibody made by guinea pigs and rabbits when they were transfused with Rhesus macaque monkey RBCs. This antibody, which agglutinated 85% of human RBCs, was named Rh after the Rhesus monkey. RH NOMENCLATURE:  Fisher-Race  Wiener

WIENER: The Rh-Hr Terminology  Rh gene produces at least 3 factors within an agglutination  Gene responsible for the Rh they actually produce agglutinogen that contains series of blood factors  R – presence of D antigen (Rh (+) )  r – absence of D  1 or ‘ – presence of C  2 or “ – presence of E  z or y – presence of both C and E  ˭rr (r double bar) – Rh null  hr- absence of d (small letter)  rh – capital tanan  Rh0 – presence of D and absence of C and E (Dce)

Fisher-Race and Weiner is based on genetic mechanisms  Rosenfield – based on the precense or absence of antigen present  ISBT (International Society Of Blood Transfusion) – assigned named of each of the blood group.

FISHER-RACE: The DCE Terminology  Ag of the system were produced by 3 closely linked sets of alleles  Each person inherits this gene on each parent  Antigens: D, d, C, c, E, e (responsible for the product of the surface of the RBC) – d (represents the absence of big D antigen)  Gene Frequency: D=85% C=70% E=30% d=15% c=80% e=98%  Rhnull – no presence of Rh; there is double deletion Phenotype: -/ Rhmod – weak expression of Rh antigen

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Lecture 4 - RH BLOOD GROUP SYSTEM 02/02/22

ROSEFIELD: Alpha/Numeric Terminology  Assigns number to each antigen of the Rh system.  Pag dili present nay (-) example: Rh: -1

Rh ANTIGENS  5 major antigens, “d” denotes the absence of “D”  Most common genotype in white: R¹r (DCe/dce)  Most common genotype in black: Rºr (Dce/dce)  Protein/Polypeptide in nature; no presence of carbohydrate on the surface of the protein  And integral part of RBC membrane; must be present on the surface of RBC antigen

IINTERNATIONAL SOCIETY OF BLOOD TRANSFUSION (ISBT): Numeric Terminology

Rh ANTIBODIES  Stimulated (through transfusion or pregnancy); not naturally present in the blood  Warm Reactive; do not bind complement  Immunologenicity: D > c > E > C > e  As little as 0.1mL Rh positive blood can stimulate antibody production  IgG1, IgG2, IgG3, IgG4 subclassses (IgG1 and IgG3 has the greatest clinical significance because they can rapidly clear the RBC that are coated by IgG1 and 3 in the circulation)  Cross placenta, causing HDFN  No discrepancies in the typing  Usually lead EXTRAVASCULAR HEMOLYSIS thus leading to Hemolytic Transfusion Reaction

WEAK D: Variation of the Rho (D)  Du type – weak expression of D antigen of the Rh Causes: 1. Genetic Weak D – complete expression of D antigen, few in number – usually a form of vertical inheritance (every generation nay juy inheritance sa weak D. Frequent in black population) 2. C trans to RHD – aka “Positioning Effect” Dce/Ce; D allele is in trans (opposite side) to the allele carrying C – still considered as Rh (+) 3. Partial D (D mosaic) – missing or altered epitope of D; produces anti-D (directed to missing epitope); strictly follow the patient and donor consideration – Rh (-) blood should be used for transfusion) 4. D(el) (D--) – no genes needed to synthesize Cc or Ee 5. Rh Null Phenotype (--/--) – no Rh antigens on its RBC; mild compensated HA, stomatocytosis, hyperbilirubinemia, low haptoglobin, increased, increased HbF, low Hb & Hct 6. Rh mod – partially suppressed Rh gene expression; similar to Rh null but milder 7. F(ce) – “f” antigen is expressed when both c and e in the cis position or located in the same haplocyte (e.g. Dce/DCE)

Lecture 4 - RH BLOOD GROUP SYSTEM 02/02/22 Rh TYPING  Detects antigen only  NO REVERSE TYPING  Specimen: Red Cells (kay ddto ma found and antigen)  Reagent: anti-D typing Ser; 22% BSA as control (monoclonal antibody is commonly used antibody)  Weak reactions should be confirmed with Weak-D (IAT) Typing

WEAK-D TYPING  Detects weak expression of D antigen on RBC surface  Follows principle of Indirect Antiglobulin Test  Specimen: Negative test from Rh Typing  Reagent: AHG (Anti-human globulin)  Washing step: the most important step in AHG phase  Then add 2 drops of AHG if negative add check cells  Check cells: “O” red cell coated with anti-D; added to a negative anti-D test  After adding 2 drops of check cells after centrifugation, the result must be positive (confirmatory); if negative- then it is not true negative (TEST IS INVALID-perform rest again)  Weak-D positive Test is reported as Rh positive SPECIAL CONSIDERATION

LW BLOOD GROUP SYSTEM:  Demonstrated as antigen present on Rhesus monkey and on majority of human RBC  Originally thought to be the same antigen as Rh  Anti-LW reacts strongly with most D-positive RBC, weakly (sometimes not at all) with Rh antigen RBC and never with Rh null cells  They are AUTOANTIBODIES (naturally occurring) – do not present clinical problems

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