Other Blood Group Systems

Discuss the importance of studying other blood group systems

Other blood group antigens may cause transfusion reactions (hemolytic or non-hemolytic) or HDFN

Define and differentiate alloantibody and autoantibody

Alloantibodies are produced following exposure to foreign red blood cell antigens

Autoantibodies target antigens on the persons own red blood cells

List the characteristics of a clinically significant antibody

They are typically:

• Active at body temperature (37°C)

• IgG (but not always)

• Able to bind complement in vivo

What are the 3 phases of IAT (Indirect antiglobulin test)?

1. Immediate Spin

2. Enhancement @ 37°C

3. Anti-human globulin

Antibody screening cells are Type __ ?

O

How does LISS enhance sensitization?

Reduces ionic environment to enhance antibody uptake

How does Albumin enhance sensitization?

Reduces zeta potential to increase lattice formation for IgG

How does PEG enhance sensitization?

Takes out H2O from system to increase lattice formation. Can only be used during AHG phase of testing

How does Proteolytic enzymes enhance sensitization?

Removes sialic acid residues from RBC surface to increase lattice formation

Examples: Papain, Ficin (most common), Bromelin

Between Anti-M, Anti-N, and Anti-S/s which is the most clinically significant?

Anti-S/s.

Mostly IgG, AHG phase & 37^oC

They will activate complement causing HTR & HDFN

MNS antigens are found on what proteins?

found on glycoproteins (glycophorins)

Is Anti-S/s IgG or IgM?

Mostly IgG, AHG phase & 37C

How many antigens are in the P blood group sytem?

P1 only antigen in P system

Is Anti-P1 IgG or IgM?

Anti-P1 is almost always IgM. Not clinically significant

What antigens are in the Globoside blood group system?

P, pk and LKE antigens

What is the clinical significance of Anti-P1?

No clinical significance!

Naturally occurring IgM

Prefers colder temps

Anti-PP₁P^k is found in people with what phenotype?

p (do not have P, P1, or pk antigens)

Why is Anti-PP₁P^k clinically significant?

Yes!

associated w/ HTR & HDN

will activate complement

associated w/ spontaneous abortions

This autoantibody is associated with paroxysmal cold hemoglobinuria (PCH)

Auto anti-P

What is clinically significant about the Kell blood group system? What are they?

Antibodies in Kell blood group system can cause hemolytic transfusion reactions

k, Kpb, and Jsb antigens all high incidence

Kell blood group antigens are encoded for by the KEL gene on chromosome __?

7

After the D antigen, this antigen is the most immunogenic

K

What is clinically significant about Kell_null?

No Kell antigens detectable on RBC

Kx expression is enhanced

Produce an antibody known as anti-Ku that reacts with all cells except Ko

Is Anti K clinically significant?

Yes!

• IgG (very few IgM), 37oC and AHG

• May activate complement

• Usually from exposure to transfusion or pregnancy

• Implicated in HTR & HDN

What is the Mcleod phenotype? What is the clinical significance?

Deletion of XK gene on X chromosome

Serologically look like a Kell null, but they have a low level of KEL expression.

Abnormal RBC morphology (stomatocytosis) and survival along with chronic granulomatous disease

What are the Lewis blood system antigens, and where are they made?

Made by tissue cells, secreted into body fluids, and adsorbed onto red cell membranes.

Le(a) & Le(b)

What alleles are needed for Le(b) phenotype?

Need one copy of Le, Se, and H alleles to be present for Le(b) phenotype

What alleles are needed for Le(a) phenotype?

If Le is present but either Se and/or H alleles are absent, Le(a) phenotype is present

This duffy group phenotype is resistant to plasmodium infections. It also lacks Fy3 and Fy5

Homozygous FY; Fy(a-b-)

What are the antigens in the Duffy Blood Group system?

Alleles for antithetical antigens are Fya and Fyb

Other antigens are possible (Fy3, Fy4, Fy5, and Fy6)

Having this phenotype can make you more suceptible to Malaria

Duffy-negative phenotype

What are the three antigens of the Kidd Blood Group System?

Jka, Jkb, and Jk3

Jk3 is present whenever Jka or Jkb are present

What is the clinical significance of Anti-JK^a ?

Anti-Jka Linked to delayed hemolysis (doesnt happen for weeks after transfusion) due to antibodies that exhibit:

• an amenestic response*

• IgG that strongly binds complement

What is an amnestic response?

An amnestic response means:

• A more rapid production of antibodies

• Antibodies produced in greater amounts

• Antibodies produced for longer periods of time.

What are the two antigens in the Lutheran system (that matter) & which one is clinically significant?

Lu^a: 5-8% of population

Lu^b: high prevalence

Lu^b: IgG (clinically significant)

In the I and i blood group system, The I antigen is found in ___ and the i antigen is found in ___?

The I antigen (adults)

The i antigen (kids)

Auto anti-I causes cold agglutinin disease after infection with ______?

Mycoplasma pneumonia

How can somone form an alloantibody against I antigen?

Alloanti-I can form in patients who never convert from i antigen to I antigen

*Remember The I antigen (adults), The i antigen (kids)

Which blood groups antigens are enhanced with enzymes?

Rh, Lewis, Kidd

Rhough UP the Lewis Kidd

Which blood groups antigens are decreased with enzymes?

MNS & Duffy

Minus Duffy

Which blood groups antigens are unaffected with enzymes?

Kell

The McLeod phenotype is very rare and is often associated with a hereditary form of?

Chronic granulomatous disease and Stomatocytosis

In the Kidd Blood Group system 2M urea will normally lyse all cells except?

Jk(a-b-) cells

Patients who produce Anti-IH are incompatible with this ___ cells

O cells due to high H antigen concentration