275 BCH Miss.Tahani Al- Shehri

objective To 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 system Each of these system contains a group of structurally related antigen These antigens may be proteins, carbohydrates, glycoproteins, or glycolipidsproteinscarbohydrates glycoproteinsglycolipids 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 ).cellstissues All antigens inherited according to mendelian laws of genetics

Introduction & principle Blood 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 SYSTEM The 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 SYSTEM To 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 SYSTEM Either 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 rate Principle 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 rate ESR 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