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MLSCI 370 > AIHA > Flashcards

AIHA Flashcards

1
Q

Purpose of performing a warm autoadsorption (W.A.R.M.)

A
  • Removes warm autoantibodies
  • To ID any clinically significant alloantibodies in patient’s serum
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2
Q

Describe how to perform a warm autoadsorption

A
  1. AutoAb removed from patients cells using W.A.R.M. (warm autoantibody removal medium) or ZZAP = DAT neg
  2. Wash and incubate DAT neg cells at 37ºC to allow warm autoAb to bind
    • alloAb will remain in plasma
  3. Sample is spun = supernatant is removed and step 2 is repeated “X” times depending on titre of autoAb
  4. Autoadsorbed (clean) plasma can now be tested against screen & panel cells to ID alloAb
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3
Q

T or F: autoadsorption using WARM/ ZZAP can be used for autoAb that have specificity to Kell, MNS and Duffy antigens

A

FALSE; WARM/ ZZAP destroys Kell, MNS, and Duffy antigens on patient’s cells
- autoAb that have specificity to these antigens will not be removed by treated cells

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4
Q

Why is the Donath-Landsteiner antibody called “biphasic?”

A

anti-P binds to RBCs at cold temperatures and causes complement-mediated hemolysis after warming to body temperature

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5
Q

Purpose of performing a cold autoadsorption

A
  • Removes cold autoantibodies
  • Cold autoAb (IgM) interfere with ABO Rh typing, Ab Scr, XM, and DATs
  • To ID any clinically significant alloantibodies in patient’s serum
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6
Q

Describe how to perform a cold autoadsorption

A
  1. AutoAb are removed from patient cells = DAT neg
    a). prewarm and wash 3-6 times w/ warm saline
    b). ZZAP removes IgM autoAb
  2. Incubate DAT neg cells at 4º C with patient plasma
  3. Sample is spun = supernatant is removed and step 2 is repeated “X” times depending on titre of autoAb
  4. Autoadsorbed (clean) plasma can now be tested against screen & panel cells to ID alloAb
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7
Q

Discuss PCH: antibody specificity, immunoglobulin class, and ability to bind complement

A

Paroxysmal (sudden onset) Cold Hemoglobinuria (Hb in urine through IVH)

  • Antibody specificity = anti-P
  • IgG that reacts in the cold!
  • binds complement right to C9 = IVH
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8
Q

What is another name for anti-P ?

A

Donath-Landsteiner Antibody

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9
Q

PCH etiology

A

often 2ry to MMRV; often seen in children

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10
Q

Discuss PCH: typical clinical symptoms

A

intermittent hemolysis with exposure to cold = anemia, fatigue, etc.

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11
Q

Discuss PCH: lab findings

A
  • same as CHD =
  • NO SPHEROCYTOSIS
  • increased nBRCs
  • anemia
  • decreased Hb
  • decreased haptoglobin
  • increased LDH
  • increased bilirubin (slow)
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12
Q

Does PCH involve IVH or EVH ?

A

IVH; anti-P binds complement right to C9

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13
Q

Describe how to do the Donath-Landsteiner Test and its purpose

A

Purpose: to identify autoanti-P in PCH

  • keep collected blood warm, and allow to clot (37C)
  • incubate tests with P(+) RBCs at 4C:
    a). patient serum = POS hemolysis
    b). normal serum = NEG
  • warm to 37C
  • spin and read for hemolysis

hemolysis = anti-P present
no hemolysis = anti-P not present

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14
Q

why can’t we use EDTA to test for PCH ?

A

always SERUM !

EDTA = false negative as it would get rid of Ca 2+ and Mg 2+ which complement needs

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15
Q

why do we add normal serum in the Donath-Landsteiner test?

A

To supply complement

  • in vivo, patient may have used up all of the complement
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16
Q

Compare/ contrast drug-related autoantibodies vs warm autoantibodies

A
  • both are active at body temp
  • methyldopa HA and WAIHA are serologically similar

Drug-related autoAb:
- IVH
- Penicillin = IgG Ab = DAT IgG pos
- Quinidine = DAT C3 pos
- Methyldopa = IgG Ab = DAT IgG+C3 pos

WAIHA:
- EVH
- IgG
- DAT IgG pos +/- C3

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17
Q

How is drug-related AIHA different from delayed hemolytic transfusion reactions ?

A
  • Drug-related AIHA is an acute hemolytic reaction
  • Delayed hemolytic is usually due to secondary exposure of an RBC antigen
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18
Q

Discuss drug-related AIHA: follow-up investigation

A

WIP

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19
Q

Causes of autoimmunity

A
  • malfunctioning T cells
  • cross-reactivity
  • molecular mimicry
  • alteration of self-antigens
  • secondary to disease
  • inherited tendency
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20
Q

Primary idiopathic autoimmunity

A
  • Ab against own RBCs
  • unknown cause
  • 60 y/o +
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21
Q

autoimmunity secondary to disease

A
  • viral or bacteriogenic disease
  • often 2° to CLL
  • WBC problems (ex: B cell lymphoma = can make Ab that’s not quite right, if malignant = makes a whole lot)
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22
Q

three main types of AIHA

A
  • WAIHA = 70%
  • cold autoimmune hemolytic anemia
    > cold hemagglutinin disease (CHD) = 16%
    > paroxysmal cold hemoglobinuria = 1-2%
  • drug-related hemolytic anemia = 12%
23
Q

instances when DAT is positive

A
  • patient alloantibodies bind donor cells
  • maternal Abs bind fetal cells
  • passive antibodies (blood products/IVIg)
  • autoantibodies
  • antibodies/complement due to drugs
24
Q

What does a DAT positive mean ?

A

In vivo binding of immunoglobulins, complement components, or both

25
Q

if a DAT is positive, what follow-up testing is needed ?

A

elution > Ab ID

26
Q

Describe warm autoimmune hemolytic anemia

A
  • often in elderly patients
  • primary idiopathic
  • secondary
    > white cell malignancies (CLL, lymphoma, MDS)
    > autoimmune diseases (Lupus, rheumatoid arthritis)
    > viral infections (children or adults)
27
Q

clinical symptoms of WAIHA

A
  • pallor
  • weakness
  • shortness of breath
  • dizziness
  • jaundice (EVH)
  • fever
  • splenomegaly
28
Q

Hematology results of WAIHA (CBC/ peripheral smear/ serological)

A

CBC:
- hemoglobin and hematocrit decreased

Peripheral smear:
- nRBC
- polychromasia
- spherocytosis
- HJ bodies (seen in asplenic individuals)

Serological indicators of EVH:
- increased bilirubin
- increase LDH
- deceased haptoglobin
- high RDW

29
Q

T or F: autoadsorptions cannot be performed if the patient has been transfused in the past three months

A

TRUE; alloantibodies can be adsorbed/removed by donor cells

30
Q

cold autoantibodies general characteristics

A
  • IgM
  • thermal range = 4°C (<15C; sometimes RT; up to 32C)
  • binds complement
31
Q

Compare harmless vs pathological autoanti-I characteristics

A

Harmless:
- titre <64
- max. thermal range = RT
- rxn not readily enhanced by albumin
- polyclonal

Pathological:
- titre >1000
- max. thermal range = 30°C
- rxn enhanced by albumin
- monoclonal (one B cell going out of control => making this autoAb)

32
Q

Causes of cold AIHA

A
  1. Primary idiopathic = common in older people
  2. Secondary to disease:
    > Mycoplasma pneumonia = anti-I
    > Erythromycin use
    > EBV = anti-i
33
Q

CHD physiological and hematological symptoms

A

Physiological:
- tingling upon cold exposure = auto anti-I attaches at 30°C = decreased blood flow = lack of O2
- when warmed up = IgM pops off BUT complement stays and works more efficiently

Hematological:
- NO SPHEROCYTOSIS
- increased nBRCs
- anemia

34
Q

treatment for CHD and PCH

A
  • avoid the cold
  • wait for secondary infection to clear
35
Q

Define acrocyanosis

A

bluish discoloration of the extremities due to decreased amount of oxygen delivered

36
Q

Describe a CHD investigation

A
  1. ID autoAb
    • panel
    • AC = pos (at RT)
      = cord cells = neg
    • titration = >1000 titre
  2. DAT
    • polyspecific = pos
    • IgG = neg
    • C3 = pos
37
Q

Describe a cold agglutinin titration

A
  • pre-warm plasma
  • serial dilution
  • test with adult O cells, patient cells, and cord cells at various temps (37°C, RT, 4°C)
  • determine titre at 4°C
  • use strength of adult vs cord cells to determine identity (anti-I vs anti-i)
38
Q

Often a cold agglutinin screen is performed before doing a ______. if the patient plasma does not react with O adult cells at 4 degrees when diluted at _____, there is no need for _______ _______

A

Often a cold agglutinin screen is performed before doing a TITRATION. if the patient plasma does not react with O adult cells at 4 degrees when diluted at 1/40 (harmless), there is no need for SERIAL DILUTIONS.

39
Q

How to find compatible blood after CHD investigation

A
  • prewarm XM samples
  • use autoadsorbed patient plasma
  • ensure monospecific anti-IgG used (don’t want to pick up complement binding)
  • only EDTA
  • transfuse using blood warmer if necessary
40
Q

Characteristics of Drug-induced HA

A
  • ONLY monospecific DAT IgG = pos
  • rarely leads to hemolysis
  • more often seen as interference
41
Q

When are blood products used as drugs?

A
  • RhIg given to Rh pos patients with ITP
  • IVIg therapy
    > monitor Hb
    > drop in Hb (<100g/L); perform DAT, Bili, LD

ITP = immune thrombocytopenia; platelet clotting disorder

42
Q

Describe methyldopa HA

A
  • positive DAT
    anemia
    autoAb produced
    serologically indistinguishable from WAIHA
    > panreacting
    > specificity
    substance sensitizing cells
    treatment = take them off drug
43
Q

Cause of methyldopa HA

A
  • due to methyldopa; antihypertensive drug used in pregnancy
  • autoantibody produced is related to dose and time
44
Q

Discuss methyldopa HA: clinical symptoms and lab results

A

Symptoms: anemia

Lab results:
- PANREACTING; serologically indistinguishable from WAIHA
- DAT = pos
- Increased LDH, bilirubin, RDW
- Decreased haptoglobin, hemoglobin

45
Q

Treatment for methyldopa HA

A

take them off drug

46
Q

Describe how Drug-adsorption (penicillin) affects testing

A
  • penicillin binds to RBCs
  • drug/RBC complex stimulates immune response
  • IgG antibodies attaches to penicillin on RBCs = mono-IgG DAT = pos
47
Q

What causes Drug-adsorption on RBCs ?

A
  • massive IV doses of penicillin
48
Q

Lab results for drug adsorption

A
  • DAT = pos; due to IgG; neg for C3d
  • AbScr = negative bc screen cells do not have penicillin
  • Eluate = neg
49
Q

What is referred to as the “innocent bystander” reaction ?

A
  • when patient makes antibodies to quinidine (a drug)
  • immune/ drug complex attaches to RBCs = complement activation = IVH
50
Q

Describe how quinidine causes AIHA

A
  • “immune complex”
  • patient makes drug Ab (IgM)
  • Ab-Ag complex binds; RBC activates complement
  • RBC destroyed by complement
  • IVH
51
Q

Immune complex lab results

A

DAT = pos (for complement only; IgM)
Ab Scr = neg
Eluate = NOT done; even if we did = still neg

52
Q

Cases when complement is only positive for DAT

A
  • Cold AIHA
  • Drug-induced (penicillin)
  • Immune complex (quinidine)
53
Q

Cause of membrane modification AIHA

A
  • Cephalosporins ADSORB to RBC
  • Modifies RBC membranes (more sticky)
  • NON-SPECIFIC BINDING of complement, IgG, IgM, IgA
54
Q

Lab results for membrane modification AIHA (cephalosporins)

A

DAT = pos (IgG and complement)
Ab Scr = neg
Eluate = neg

  • bc drug Ab are not represented on screen cells

MLSCI 370 (7 decks)

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