Immune hemolytic anemia

What is alloimmune anemia caused by?

Foreign antigens

What is autoimmune anemia caused by?

Self antigens

What is drug-induced anemia caused by?

Drug or drug complexes, damage red blood cells

What do autoantibodies do?

• May cause red blood cell destruction

• may interfere with testing

• most react with high incidence rbc antigens 

What are autoantibodies?

A failure of the immune system where antibodies are directed against self

What is seen in the lab with autoimmune hemolytic anemia?

• autoantibodies

• RBC destruction

• increased retic, bilirubin, LDH

• decreased haptoglobin

• Hgburia/hgbemia 

What tests in the blood bank indicate an autoantibody? 

• Positive DAT

• positive autocontrol 

What is true of cold reactive autoantibodies?

• Bind best at 4 degrees

• benign

• IgM

• Activate complement 

• low titer 

What is the most common type of autoantibody?

Cold reactive

What are the most common cold autos?

• Anti I

• Anti IH

• Anti H

• Anti i

If a cold auto is present what can be done to obtain a valid abo type?

• warm reagents and sample before testing

• adsorb serum with patient’s own cells or REST 

What can autos do to an Rh control?

False positive

If there is an autoantibody present what will the DAT be?

Positive

To to a cross match with a cold auto present what must be done?

Crossmatching must be preformed with prewarmed sample

What causes cold hemagglutinin disease?

• idiopathic 

• mycoplasma pneumoniae 

What is the antibody that causes cold hemagglutinin disease?

• Anti I

• IgM

• activated complement 

What infection can result in the development of an anti i?

Infectious mono 

What are the characteristics of an anti i?

• high titer IgM

What causes the development of paroxysmal cold hemoglobinuria?

Viral illness in children

What are the characteristics of the antibody that causes PCH?

• biphasic IgG

• anti P 

What test is available for PCH antibody?

Donath-Landsteiner test

What kind of antibodies are warm autos?

• IgG

• often fix complement 

• often against high incidence antigens 

What does the patient often present with when there is a warm autopresent?

Anemia 

What tests are affected by a warm auto?

• ABO: not usually

• Rh control: positive

• Weak D control: positive 

• DAT: positive

• IAT and ab: all positive at AHG

What can be done to detect warm autoantibodies?

• antigen negative panel

• autoadsorption

• adsorption with donor cells 

• patient antigen typing (chloroquine treated patient cells) 

What is the treatment for warm autoantibodies?

• treat underlying disorder

• steroids

• splenectomy

• immunosuppressive drugs 

• transfusion 

When is drug induced hemolytic anemia most often detected?

• during investigation of hemolytic anemia

• unexpected results in routine testing: Positive autocontrol and DAT

What is the mechanism of drug induced hemolytic anemia?

• immunogen formed by drug and plasma protein

• IgG or IgM produced that recognizes the drug

• immune complex binds to RBCs and causes complement lysis

What drugs often cause immune complex hemolytic anemia?

• quinidine

• sulfonamides 

What is done to prove the presence of a drug induced antibody?

Serum, drug in question and ABO compatible red blood cells. 

What are the testing indicators of drug induced immune complexs?

• positive DAT

• indicators of hemolysis 

What is the treatment for drug induced immune complexes?

• discontinuing the drug

• steroid 

What is the mechanism of drug adsorption anemia?

• Drug binds to rbcs

• antibody is formed (IgG or IgM)

What drugs often cause drug adsorbtion hemolytic anemia?

• penicillin

• cephalosporins 

What pattern in testing does drug adsorption hemolytic anemia cause?

• Positive DAT

• IAT usually negative

• Crossmatched usually compatible 

What is done to prove drug adsorption hemolytic anemia?

Serum and eluate against drug-coated cells

What is the treatment for drug adsorption hemolytic anemia?

Discontinuing drug

What is the mechanism for membrane modification?

• non-immunological process

• drug modifies the rbc membrane 

• plasma proteins (IgM, IgG, complement) non-specifically bind to RBCs

What lab test is positive with membrane modification hemolytic anemia?

• Positive DAT (3% of patients of Kelfin) 

Is treatment necessary for membrane modification?

No usually

What is the mechanism for drug autoantibody formation?

• exact cause unclear

What are drug autoantibodies indistinguishable from?

WAIHA, but only occurs in the presence of the drug 

What drug has been known to cause drug autoantibodies?

Aldomet

What tests are positive with drug autoantibody hemolytic anemia?

• positive DAT

• resembles WAIHA

What is the treatment of drug autoantibody hemolytic anemia?

• discontinue drug

• hemolysis is usually insignificant

What are the signs of hemolytic anemia?

• decreased HCT/hemoglobin

• increased retic count

• increased bilirubin 

• increased LDH

• decreased haptoglobin