2 - BLOOD GROUP SYSTEMS: AN INTRODUCTION

BLOOD GROUP ANTIGENS

Refer to the genetically encoded antigen system on the erythrocytes, leukocytes, platelets and plasma

BLOOD GROUP ANTIGENS

Only relatively small number of blood group antigens is considered significant but more than 6oo have been described

immunogens

The majority of the blood group antigens are _____________ - they are able to elicit antibody-mediated immune response when introduced as a foreign substance into a responsive host

Characteristics of antigens that determine their immunogenicity

• Degree of foreignness

• Molecular size and configuration

• Temperature, pH and ionic environment

• Antigenic complexicity (measured by the number of available epitopes)

A, B, D (Rho)

these 3 antigens are certainly the most immunogenic and thus all blood transfused must be matched for these antigens between the blood donor and the recipient

K

It is the next most immunogenic after the D antigen

K

Fya

C, c, E, e

After the D antigen, ___ is the next most immunogenic, with _____ and other antigens within the Rh system (__, __, __, __)

Fyb, Jka, Jkb, and s

Other common blood groups are much less immunogenic (4)

Red cell antigens

Lewis

_________________ are usually proteins, glycoproteins, lipoproteins or glycolipids are embedded to or protruding from the RBC membrane (except _____ antigen)

Low incidence antigens

• These antigens are found in less than 1% of the population

• These are called private or family antigens

Low incidence antigens

Cw, V, Kpa, Jsa Lua, Mo, Vw Dia, Wra, and Cob are examples

High incidence blood group

• These antigens are found in more than 99% of the population

• They are also called public antigens

High incidence blood group

Kpb, k, Jsb Lub, l, Ge, Tja, Vel, Yta, Dib, Coa, and U are examples

Autosomal co-dominance

the most common pattern or inheritance of blood group genes

Genes

are inherited equally by males and females and they are always expressed

both

If one inherits the A and B genes, _____ A and B antigens are detected on the RBC

ABIPLL

A, B, I, P Lewis, and Lutheran

The RBC antigens that are not fully expressed at birth include (6)

Immunoglobulins

are protein molecules that are produced in response to antigenic stimulation and that demonstrate specific antibody activity.

IgG

IgM

IgA

The majority of clinically significant blood group antibodies fall into ___ and ___ immunoglobulin classes with occasional ___ forms.

Alloantibody

it reacts with a foreign antigen not present on the patient's own RBC.

Autoantibody

it reacts with an antigen on the patient's own cells and with that same antigen on the cells of other individuals

Autoantibody

it reacts with an antigen on the patient's own cells and with that same antigen on the cells of other individuals

Naturally occurring

Alloantibodies to erythrocyte antigens are either:

the antigenic stimulus for their production is unknown

Naturally occurring antibodies

Alloantibodies to erythrocyte antigens are either:

appear in the serum who lack the corresponding antigen

immune antibodies

Alloantibodies to erythrocyte antigens are either:

• they are produced as a result of immunization to foreign erythrocyte antigens either by:

  • exposure through transfusion of blood components

  • through pregnancy (usually at the time of delivery)

1. blood transfusion

2. pregnancy

Immune antibodies are produced as a result of immunization to foreign erythrocyte antigens by (2)

ABO system

differs from other blood group system and that it is the only one in which there are naturally occurrina antibodies in the plasma/serum.

ABO system

most important in transfusion therapy

Naturally occurring anti-A and anti-B

are potent hemolytic antibodies

Life-threatening acute hemolytic transfusion reactions

may occur from an ABO-incompatible transfusion.

ABO System

They are also found on tissue cells, platelets, lymphocytes and in a soluble form in the body fluids and secretors.

Rho(D)

The most potent among the antigen in the Rh system

Rh-positive blood

The presence of D antigen denotes?

85%

15%

__% of the US Caucasian populations are Rh-positive and __% are Rh-negative.

Kell, Kidd, Duffy

Antigen systems that produce warm-reacting antibodies. They react at 37C and are considered as clinically significant because they cause hemolytic disease of the newborn (HDN) and HTR

K, k

Major antigens of Kell

Jka, Jkb

Major antigens of Kidd

Fya, Fyb

Major antigens of Duffy

Lewis

P

I

MNSs

Antigen systems that produce warm-reacting antibodies. They react at 37C and are considered as clinically significant because they cause hemolytic disease of the newborn (HDN) and HTR

Lea, Leb

Major antigens of Lewis

P1

Major antigens of P

I, i

Major antigens of I

M, N, S, s

Major antigens of MNSs