Immune Hematology

L Bonstien PhD

E J Dann MD

RED BLOOD CELL SURFACE MAMBRANE

BLOOD GROUPS Systems ANTIGENS and Chromosomal Location

ABO system

• Carbohydrate Antigens • ABO Antigens are not unique to RBC.They

are present on other cells and in bacteria and plants

• 80% of humans excrete ABO antigens in their secretions (Secretors)

• Secretors (of Antigens) = Se/Se, Se/se• Non secretors = se/se

Incidence of ABO blood groups in Israeli population

סוג

TYPE

שכיחותINCIDECE

סוג

TYPE

INCIשכיחותDECE

+A38%-A4%

+B16%-B2%

+AB6%-AB1%

+O30%-O3%

D- are 15 % of the population less then world prevalence

Possible genotype and Phenotype when the parents are O

and A or B

THERE IS A SINGLE SUGAR DIFFERENCE BETWEEN THE A AND B TYPE

Indirect agglutination test known RBC with patient serum

Intra Vascular Hemolysis Due to infusion of A RBC to O recipient

Antigens of Rh system• Are encoded by 2 homologous genes RHD and RHCE

• Transport proteins in the RBC membrane• Basic unit is a quartenary complex of 2RhAG

+2RhD or 2RhAG+2RhCE• D is the significant immunogen cde/cde are D- or

rr 15%• 32% CDe/cde 17%CDe/Cde 13%cDE/cde

14%CDe/cDE 4%cDE/cDE Other genotype are almost all +

• There is no d protein it is a null protein

Rh system

• 15% of caucasian and 5% of black are Rh-

• 1% of asian popularion are Rh-

• D+ are marked D and negative are d

• are Rh+ D/D or D/d, are Rh- d/d

BLOOD TYPING1. ABO and Rh blood group is determined

2. USE of sera of anti A B sera anti D with patients erythrocytes

3. Use of Pt serum to check for anti A and anti B with known A1 and B RBC

4. Serum is screened for important antibodies by an indirect antiglobulin test on a large panel of antigenically-typed red cells

patient RBC with commercial sera serum Patient

Anti A Anti B Anti D A RBC

B RBC + -- +

-- + A+

+ + +

-- --AB+

-- + --

+ --B -

-- -- +

+ +O+

Hoffbrand Petit Moss essential Haematology

4th edition

IgM antibodies can activate complement and cause intra

vascular hemolysis

IgG Antibodies usualy cause extra vascular hemolysis

Direct Anti Globulin Test(Direct Coombs)

• Anti human globulin helps to complete the reaction in presence of IgG

• DAT screen for Ab on RBC cells attached in vivo an example hemolitic disease of the newborn

• Indirect Anti Globulin Test for Ab in the pt serum . The reaction between the Ab and Ag is in vitro

• anti IgG Coombs reagent is mono specific

• IgG + anti C3Coombs reagent is poly specific

RBC RBC

Antibody is attached to Antigen on Erythrocyte

surface membrane

RBCRBC

Adding anti Human Globulin In Vitro

Direct Anti Globulin Test(Coombs’)

Indirect Anti Globulin Test (Indirect coombs) survey of

acquired antibodies in patient serum

Allo antibodies versus Auto antibodies• Allo Ab are antibodiy against antigen from foreign

blood • Versus auto Ab which react with self Red Blood

Cell Ag

Antibodies screening

Indirect Anti Globulin Test

Indirect Anti Globulin Test

Positive test in

Presence of Ag

Direct Anti Globulin TestAim Detection of Ab on Pt

RBC in cases of Hemolysis

A case study

• A pt with anemia, fatigue, respiratory distress on exertion

• Lab results anemia and high reticulocyte count

• Positive Direct Anti Globulin test (DAT)

• High LDH high billirubin

• Dg autoimmune hemolytic anemia

Rx steroids, packed red blood cells folic acid

Hemolytic disease of the new born - HDN

Appearance of Ab in the blood stream of a pregnant woman

against paternal Ag present in fetal blood

HDN IgG Ab that cross the placenta

Ist exposure (Pregnancy)

Second exposure (Second preg) or post infusion of Rh + blood

HDN Rx

•UVa exposure to decrease levels of un conjugated billirubin

•Exchange transfusion of blood

•Direct anti globulin test to fetal blood or new born

•Indirect globulin test to maternal serum

•If mother has no Anti D check for other Ag Yta for example

HDN Direct Anti Globulin Test

HDN prevention by injection of anti D (Proginin) 500 iu during pregnancy at week 28 and 34 at birth if baby is having a Rh+ another dose is indicated within 72 hours

Antibodies found in a pt

Antibodies on RBC

Antibodies in serum

-+Post transfusion

-+Post pregnancy

++A new born to mother who carry

Ab

+possibleAuto immune disease

Thank You

Uribamba Valley Peru 5/2004