275 BCHMiss.Tahani Al- Shehri

objectiveTo determine the blood group and therefore

the type of antigen carried on the surface of erythrocytes in the ABO system

To test the availability of the Rh factor ( D antigen) on the surface of erythrocytes

To determine ESR

Introduction & principle ABO blood Group system is one of 29 genetically

independent human blood group systemEach of these system contains a group of

structurally related antigen These antigens may be proteins, carbohydrates,

glycoproteins, or glycolipids some of these antigens are also present on the

surface of other types of cells of various tissues and bilogical fluid ( Saliva , milk , seminal fluid urine , ovarian cyst fluid and gastric fluid ).

All antigens inherited according to mendelian laws of genetics

Introduction & principleBlood group antigens must be

determined to secure a safe practical of blood transfusion.

They are also useful in determining familial relationships in forensic medicine .

BIOCHEMISTRY OF THE ABO SYSTEMThe ABO antigens are terminal sugars found at the end of

long sugar chains (oligosaccharides) that are attached to lipids on the red cell membrane.

The A and B antigens are the last sugar added to the chain.  The "O" antigen is the lack of A or B antigens but it does have the most amount of next to last terminal sugar that is called the H antigen

Production of A, B, and H antigens The production of A, B and H antigens are controlled by the

action of transferases.  These transferases are enzymes that catalyze (or control) addition of specific sugars to the oligosaccharide chain. The H, A, or B genes each produce a different transferase, which adds a different specific sugar to the oligosaccharide chain.

BIOCHEMISTRY OF THE ABO SYSTEMTo understand the process let's look at the

sequence of events: Precursor chain of sugars is formed N-acetylglucosamine (G1cNAc) and Galactose

(Gal). H gene causes L-fucose to be added to the

terminal sugar of precursor chain, producing H antigen (shown in this diagram)

BIOCHEMISTRY OF THE ABO SYSTEMEither A gene causes N-acetylglucosamine (G1cNAc) to

be added to H substance, producing A antigen,

or B gene causes D-galactose (Gal). to be added to H

substance, producing B antigen.

If both A and B genes present, some H-chains converted to A antigen, some converted to B antigen.

If H gene absent (extremely rare), no H substance can be formed, and therefore no A or B antigen. Result is Bombay blood group.

Rh group Rh group is determined using an agglutinating IgM anti D

Erythrocytes sedimentation ratePrinciple When anticoagulant blood is allowed to

stand, the red cells settle down due to rouleaux formation to wared the bottom as the red cells are more dense than plasma( Sediment under the effect of gravity )

The rate at which red cells settle down in an hour is known as Erythrocytes sedimentation rate

Erythrocytes sedimentation rateESR is used clinically as non-specific

screening test to detect the presence of infection

It used as well as means of monitoring the status of chronic inflammatory disease such as rheumatoid arthritis.

γ – globin & Fibrinogen

ESR