- titre <64 - max thermal range (20-24C; most below) - rxn not readily enhanced by albumin - polyclonal

- primary idiopathic = tend to see in older people - secondary to disease > Mycoplasma pneumonia = anti-I > use erythromycin > EBV = anti-i

cold hemagglutinin disease - symptoms: tingle due to lack of O2 = go inside = warm up; IgM pops off BUT complement stays and works more efficiently - when blood cools down to 30C = ears, nose, etc first things to go down => auto anti I attaches at 30C = decreased blood flow; O2 used up from those cells unable to move freely => binds complement - no spherocytosis - increased polychomasia - anemia symptoms (fatigue, etc.)

AIHA Flashcards by Richen Basig

theories of autoimmunity

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

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primary idiopathic autoimmunity

Ab against own RBCs
unknown cause
60 y/o +

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autoimmunity secondary to diseas

viral or bacteriogenic disease
often 2y 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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three main types of AIHA

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

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instances when DAT is positive

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

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in vivo binding of immunoglobulins, complement components, or both

DAT positive

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

elution

Ab ID

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warm autoimmune hemolytic anemia

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

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clinical symptoms of WAIHA

pallor
weakness
shortness of breath
dizziness
jaundice (EVH)
fever
splenomegaly

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hematology results of WAIHA

CBC
- hemoglobin and hematocrit decreased
- peripheral smear
 > nRBC
 > polychromasia
 > spherocytosis
 > HJ bodies (seen in asplenic individuals)

other indicators of EVH

increase bilirubin
increase LDH
decease haptoglobin
high RDW

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

T as alloantibodies might be removed by donor cells

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cold autoantibodies general characteristics

IgM
thermal range = 4C (<15C; sometimes RT; up to 32C)
binds complement
specificities

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harmless autoanti-I

titre <64
max thermal range (20-24C; most below)
rxn not readily enhanced by albumin
polyclonal

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pathological autoanti-I

titre >1000
max. thermal range (30-32C)
rxn enhanced by albumin
monoclonal (one B cell going out of control => making this autoAb)

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cold AIHA

primary idiopathic = tend to see in older people
secondary to disease
> Mycoplasma pneumonia = anti-I
> use erythromycin
> EBV = anti-i

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CHD

cold hemagglutinin disease
- symptoms: tingle due to lack of O2 = go inside = warm up; IgM pops off BUT complement stays and works more efficiently

when blood cools down to 30C = ears, nose, etc first things to go down => auto anti I attaches at 30C = decreased blood flow; O2 used up from those cells unable to move freely
=> binds complement
no spherocytosis
increased polychomasia
anemia symptoms (fatigue, etc.)

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treatment for CHD

just avoid the cold

ACROCYANOSIS

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

CHD investigation

identify autoAb

panel
auto control (at room temp = pos)
cord cells (without autoanti-I = neg)
titration (>1000)

DAT = pos

polyspecific pos
monospecific = only pos for C3

cold agglutinin titration

pre-warmed patient plasma is serially diluted
test with adult O cells, patient cells, and cord cells at various temps (37C, RT, 4C)
determine titre at 4C
use strength of adult vs cord cells to determine identity (anti-I vs anti-i)

finding compatible blood (follow-up CHD investigation

prewarm
use autoadsorbed plasma
ensure monospecific anti-IgG used (don’t want to pick up complement binding)
ensure EDTA sample used
transfuse using blood warmer if necessary

PCH

paroxysmal (sudden onset) cold hemoglobinuria (Hb in urine through IVH)

antibody specificity is anti-P
AKA Donath-Landsteiner Ab
IgG that reacts in the cold!
binds complement right to C9
hemolysis (IVH bc of C9)

PCH etiology

often 2ry to MMRV; often was found in children

symptoms of PCH

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

lab findings for PCH

similar to CHD | - decrease Hb, haptoglobin; increase LDH, bilirubin (takes a while to increase)

treatment for PCH

wait for underlying infection to clear; avoid cold

Donath-Landsteiner Test

- PCH - collect blood, keep warm, and allow to clot (37C) - incubate serum with P(+) RBCs and normal serum at 4C - warm to 37C - spin and read for hemolysis hemolysis = anti-P present no hemolysis = anti-P not present

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

- always serum! bc EDTA will cause a false negative as it would get rid of Ca 2+ and Mg 2+ which complement needs

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

to supply complement | - ensuring that there is enough complement source; bc in vivo, patient may have used up all of the complement

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 _______ _______

titration 1/40 serial dilutions

drug induced HA

- positive DAT could be caused by dug - rarely leads to hemolysis - more often seen as interference - should be considered in DAT workup

when are blood products used as drugs?

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

methyldopa HA

- antihypertensive drug used in pregnancy: Aldomet - autoantibody related to dose and time - positive DAT - anemia - autoAb produced - serologically indistinguishable from WAIHA > panreacting > specificity - substance sensitizing cells - treatment = take them off drug

drug adsorption (penicillin)

- IV (massive doses) - drug binds to RBC - drug/RBC complex stimulates immune response - IgG Ab attaches to penicillin

lab results for drug adsorption

- DAT = pos; due to IgG; neg for C3d - antibody screen = negative bc screen cells do not have penicillin - Eluate = neg

immune complex "innocent bystander"

Quinidine = antimalarial drug

Quinidine AIHA

- patient maks drug Ab - Ab-Ag complex binds; RBC activates complement - RBC destroyed by complement - IVH

immune complex lab results

- DAT = pos (for complement only) - Ab scr = neg - Eluate = NOT done; even if w did = still neg

if complement is only positive from DAT

either cold auto, drug-induced, or immune complex

membrane modification (cephalosporins) AIHA

- uses adsorption mechanism - modifies RBC membrane (makes it sticky) - nonspecific protein binding > complement, IgG, IgM, IgA

lab results for membrane modification

- DAT = pos (due to IgG and complement) - Abscr = neg - eluate = neg *bc drug Abs not specific Abs*