5 - MINOR BLOOD GROUP SYSTEMS

Lewis Antigen

called plasma antigens

Lewis Antigen

differs from all other blood groups in that it is soluble and found in saliva and plasma

Lewis antigen

The Lewis antigen is not a true blood group antigen; it is mainly acquired from the body tissues and attaches itself onto the red cell surface later in life

Le (a-b-)

most infants are __________ since the antigen is fully developed at age six

Hh and Sese genes

The expression of Lewis antigens is influenced by the presence of these 2 genes

Se gene

This gene determines secretor status; it is a gene that produces the ability to secrete water-soluble blood group specific substances in the tissues

H gene

This gene produces the ability to secrete H antigen (the basic matrix of the ABO system)

H and Se genes

When these 2 genes are present together, they convert the Lea substance to Leb substance but a small residue of the Lea substance remain unconverted

H gene

the basic matrix of the ABO system

Le, le

The Lewis antigen is inherited by means of these 2 genes?

Lewis positive (Le) gene

This gene converts a precursor material to Lea substance

Lewis negative (le) gene

This gene cannot convert a precursor material to Lea substance

Lewis antigens

These antigens become weaker during pregnancy and females of Lewis-type Le(a-b+) may type as Le(a-b-) during this period

1. Le (a-b+)

2. Le (a+b-)

3. Le (a-b-)

3 Lewis phenotypes

Le (a-b+)

Lewis phenotype present in secretors

Le (a+b-)

Lewis phenotype present in nonsecretors

Le (a-b-)

Lewis phenotype usually found in secretors

• Le (a-b-)

• Le (a-b+)

• Le (a+b-)

Rules regarding Le antigen expression:

• A lele individual will not produce any antigen, i.e., __________

• A person who inherits at least one Le gene and at least one Se gene will be Leb positive, i.e., _________

• A person with at least one Le gene and sese genes will be __________

Se gene

This gene controls ABH secretions, but has no control over Le secretion

A, B, H, Lea, Leb

Genes inherited: Le, H, Se

Phenotype: Le (a-b+) 70%

Adult level rxn with anti-Lea and anti-Leb: o ; +

Secretors: ?

Only Lea substances

Genes inherited: Le, H, se

Phenotype: Le (a+b-) 20%

Adult level rxn with anti-Lea and anti-Leb: + ; o

Secretors: ?

10% of Le (a-b-) are secretors

Genes inherited: Le, H, Se

Phenotype: Le (a-b-)

Adult level rxn with anti-Lea and anti-Leb: o ; o

Secretors: ?

Genes inherited: Le, H, se

Phenotype: Le (a-b-)

Adult level rxn with anti-Lea and anti-Leb: o ; o

Secretors: ?

Anti-Lea

most commonly found; it is usually accompanied by anti-Leb especially in Blacks possessing Lewis type Le (a-b-)

Anti-Lebh

Anti-LebL

Anti-Leb exists in these 2 forms

Anti-Lebh

Anti-LebL

Identify the 2 forms of Anti-Leb that manifest these reactions:

O Le (b+) → III

A2Le(b+) → III

A1Le(b+) → o/w

H substance → neutralized

Lewis antibodies

Found in individuals who have never been transfused or received other antigenic stimuli

Lewis antibodies

Are not known to cause hemolytic disease of the newborn because:

• Most infants do not take up the soluble Lewis antigen from the plasma to the red cells by birth

• Lewis antibodies are invariably IgM in form and too large to cross the placental barrier

Lewis antibodies

invariably IgM in form and too large to cross the placental barrier

MNSs

Discovered by Landsteiner and Levine in 1972

MNSs

An individual is either MM, MN or NN

MNSs

demonstrates dosage effect

MM or NN

In MNSs system, these 2 antigens react stronger than MN with Anti-M and Anti-N

M and N

are co-dominant alleles in paternity testing; the antigen are fully developed at birth

• secretions

• transfusion or pregnancy

• naturally

The MNSs system differs from the ABO antigen in three ways:

• Antigens found on red cells and some tissues but not on ___________

• Anti-M and anti-N are usually a result of a (2)

• Anti-M and anti-N rarely occur __________

MNS antibodies

Anti-M and anti-N are IgM and react best at 4°C

• Transfusion reactions

• paternity testing

• HDN

Clinical importance of MNSs system is in:

• ______________________ due to anti-S or anti-s

• Medico legal case (_________________)

• ____ (due to anti-S, anti-s, anti-U

The alleged father is not excluded

Paternity testing

• Father - MM

• Mother - NN

• Baby - NN

Reactions:

Anti-M ; Anti-N

• Father MM = 4+ ; Neg

• Mother NN = Neg ; 3+

• Baby MN = 3+ ; 3+

Is the alleged father excluded?

I antigen

It is a public antigen

i antigen

I antigen

__________ is found in cord blood cells; by the time is child is 1-1/2 - 2 years old, he/she will mostly have __________

Anti-l

a cold agglutinin that is present in low titers in healthy adults

Anti-I

High titers are seen during and following infections with Mycoplasma pneumoniae, in elderly with autoimmune hemolytic anemia and patients with cancer of the RES

Anti-I

an IgM and has never caused HDN

Anti-I

may cause problem because it can agglutinate all adult cells, including px own cells at RT

Autoabsorption prior to compatibility tests and pre-warmed crossmatch

Blood should be warmed when given to a recipient who has anti-l

Remedies for problems involving Anti-A antibodies

P system

The antigens formed are P1, Pk, P

P1

P2

The ___ antigen is present on the red cells of 79% of the population; individuals who lack P1 are termed ___

p

Individuals who lack P1, P2, or Pk antigens are termed?

Anti-P1

an IgM and has never caused HDN but has occasionally caused a transfusion reaction; in transfusion, recipients with anti-P1 must be given P1 negative units

Anti-P

has the specificity of the biphasic Donath-Landsteiner antibody present in Paroxysmal Cold Hemoglobinuria

Xga antigen

It is found more frequently in females, as it is associated with its mode of inheritance on the X chromosome

anti-Xga

Clinically, it has not been implicated in HTR or HDN but it possesses the ability to bind complement

Kell antigens

are produced from a precursor substance Kx that is coded by he gene XK on the X chromosome

Kell antigens

The popular antigens under this system are the K and k antigen

K antigen

It is immunogenic and therefore, exposure to K+ red cells results to production of anti-K antibodies; the frequency of K is low (9%); hence, it is not difficult to find compatible blood for patients with anti-K

k antigen

It has a frequency of 99.9% and for this reason anti-k is rarely encountered

Kx substance

precursor substance of Kell antigens

Kx substance

It is present on the WBC and RBC of most individuals

McLeod phenotype

If Kx is lacking from red cells, the cells have an abnormal shape (acathocytes) and a reduced in vivo survival; such individuals are said to have what phenotype?

Chronic granulomatous disease

The absence of Kx from leukocyte has been described to be individuals with this disease; the leukocytes are able to phagocytose but not kill bacteria; patients with this disease have recurrent bacterial infection?

Kell antibodies

Are IgG and are stimulated by transfusion or pregnancy; they can cause HDN and HTR

Duffy antigens

The most important antigens are Fya and Fyb

Fya

It is more immunogenic than Fyb

1. Fy (a+b+)

2. Fy (a+b-)

3. Fy (a-b+)

4. Fy (a-b-)

4 phenotypes of Duffy antigens

Fy(a-b-)

Fy(a+)

Fy(b+)

Red cells that are _______ are resistant to penetration from Plasmodium vivax merozoite but ______ or ______ cells are susceptible to this parasite since they invade the red cells at the Duffy antigens

Duffy antibodies

Most antibodies are IgG and can cause HTR and HDN

Jka and Jkb

2 Kidd antigens that are weakly immunogenic

1. Jk (a+B-)

2. Jk (a+b+)

3. Jk (a-b+)

4. Jk (a-b-)

4 phenotypes of Kidd Blood Group System

Jk (a-b-)

More commonly found in Orientals particularly Filipinos

Kidd antibodies

This blood group system is particularly notorious for its danger in causing severe and often fatal delayed hemolytic transfusion reaction; also known to cause HDN

1. Chido and Rodgers antigens

2. Sd (Sda) antigens

3. Bg antigens

ANTIGENS OF HIGH FREQUENCY, HIGH TITER AVIDITY ANTIBODIES (HTLA) (3)

Chido and Rodgers antigens

Part of the C4molecule (complement) and are not part of the red cell membrane

Sd (Sda) antigens

Are distributed in mammalian tissues and body fluids

Bg antigens

These antigens are expressed on both leukocyte and red cells:

• Bga = HLA-B7

• Bgb = HLA-B17

• Bgc = HLA-B28