WAIHA Flashcards
(101 cards)
1
Q
What do most autoantibodies react with?
A
High incidence RBC antigens (Rh blood group)
2
Q
What do autoantibodies do?
A
Agglutinate, sensitize, or lyse RBCs of random donors and self
3
Q
What are some discrepancies caused by?
A
Autoantibodies coating RBCs
4
Q
If DAT is positive, what does that mean?
A
There is a positive autocontrol, which means there’s an autoantibody
5
Q
Individuals who make antibodies against antigens on their own red blood cells (autoantibodies) with resultant hemolysis suffer from ____
A
autoimmune hemolytic anemia (AIHA)
6
Q
Is it AIHA if person has not been recently tranfused?
A
No
7
Q
When your bone marrow is keeping up with the amount of RBCs being destroyed?
A
Compensated anemia
8
Q
What is the retic count for compensated anemia?
A
High
9
Q
What is the H/H for compensated anemia?
A
Mildly low
10
Q
blood test that measures how fast red blood cells called reticulocytes are made by the bone marrow and released into the blood
A
Retic count
11
Q
the proportion, by volume, of the blood that consists of red blood cells expressed in %
A
hematocrit
12
Q
the oxygen-carrying protein pigment in the blood, specifically in the red blood cells expressed as g/dL
A
hemoglobin
13
Q
When your bone marrow is not keeping up with the amount of cells being destroyed
A
Uncompensated anemia
14
Q
What is seen in peripheral smear of someone with uncompensated anemia?
A
Macrocytosis and spherocytosis
15
Q
What is the retic count for uncompensated anemia?
A
more than 3%
16
Q
What is the level of unconjugated bilirubin and LDH in uncompensated anemia?
A
High
high LDH = damaged tissues
17
Q
Bilirubin that is bound to a certain protein (albumin) in the blood
A
Unconjugated bilirubin
18
Q
What is the haptoglobin levels in uncompensated anemia?
A
Low
19
Q
How do you confirm if someone has AIHA?
A
DAT (and eluate if positive)
20
Q
Can AIHA antibodies be warm or cold reactive?
A
Most are warm, some are cold
21
Q
Can AIHA antibodies be drug induced?
A
Yes
22
Q
What do cold reactive autoantibodies react best with?
A
Enzyme-treated cells (ficin at IS)
23
Q
What class of Ig are cold reactive autoantibodies?
A
IgM
24
Q
Can cold IgM autoagglutinins activate complement in vitro?
A
Yes, by binding to RBC surface (causing a positive DAT)
25
At what phase can reactivity be seen in cold reactive autoantibodies?
At Coombs (AHG) using polyspecific AHG
26
What AHG is used for D/weak D typing?
Monospecific IgG AHG
27
What can be done to remove cold autoantibodies coating RBCs?
Use monoclonal IgG reagents, wash cells at 37C, ADSORPTION
28
Do cold reactive autoantibodies interfere with detection and ID of RBC ALLOantibodies?
YES
29
Do benign cold autoantibodies interfere with using polyspecific AHG?
Yes
30
What happens when RBCs are heavily coated with cold autoantibodies?
False positive reactions with ABO reagents; spontaneous agglutinations (so need to wash at 37C)
31
Can you use pre-warmed testing for cold autoantibodies?
Not for recently transfused patients (within 3 months) or inaccurate transfusion history
32
What specificity do most cold autoantibodies have?
Cold anti-I specificity (NOT little i)
33
What specificity do some cold autoantibodies have?
Cold anti-H in group O and A2 people who have the most H antigen so they react best
34
Lacks H antigens; therefore anti-H is a potent alloantibody which reacts at cold temp with all cells except rare Oh cell and capable of causing rapid intravascular destruction
Bombay
35
Occurs in old people (around 50); antibody specificity is always anti-I, usually seasonal and not severe
Idiopathic Cold AIHA (Cold Hemagglutinin Disease)
36
What is the clinical criteria for diagnosis of Idiopathic Cold AIHA (Cold Hemagglutinin Disease)?
Acquired hemolytic anemia with a history of acrocyanosis, jaundice, Raynaurd's and hemoglobinuria on exposure to cold
37
What serological tests are performed for Idiopathic Cold AIHA (Cold Hemagglutinin Disease)?
DAT; cold agglutination titer; reactivity in patient's serum
38
What causes Paroxysmal Cold Hemoglobinuria (PCH)?
a biphasic IgG autoantibody that fixes complement at low temperature, causing intravascular hemolysis, but ultimately dissociates at a higher temperature
39
Who is PCH common seen in?
Children with viral illnesses, but incidence of 1-2%
40
How do you solve problems associated with cold agglutinins?
Get out of cold climate
41
What is severe and rapidly progressive anemia?
Intravascular anemia
42
What percent of warm reactive autoantibodies (WAIHA) are true autoimmune hemolytic anemia (AIHA)?
70%
43
Is WAIHA severe enough to require a transfusion?
Yes
44
What is the hemoglobin for people with WAIHA?
low levels less than 7 g/dL
45
What causes Warm Autoimmune Hemolytic Anemia (WAIHA)?
Gradual onset that can be accelerated by trauma, surgery, pregnancy, or psychological stress
46
What are the symptoms of WAIHA?
pallor, weakness, dizziness, labored breathing (dyspnea), jaundice, unexplained fever
47
Is hemolysis in WAIHA acute at onset?
Yes, it may stabilize or accelerate at variable rate
48
What is seen in a peripheral blood smear of someone with WAIHA?
Polychromasia, spherocytosis, nRBCs
49
If your retic count goes down, what does that mean?
Your bone marrow cannot compensate for the amount of RBCs destroyed?
50
What causes the RBC hemolysis in WAIHA?
IgG, with IgG subclasses 1 and 3 (with IgG3 being the most destructive)
51
At what phase does IgG react best at in WAIHA?
At Coombs (AHG)
52
Do IgG of WAIHA agglutinate after 37C incubation?
No, only after AHG
53
Do IgG of WAIHA activate complement?
Yes
54
Are IgG of WAIHA enhanced by enzyme?
Yes
55
Do IgG of WAIHA react with high-incidence RBC antigen and have a general specificity with Rh group?
Yes, so Rh typing can be a problem
56
Is ABO group affected by WAIHA?
No
57
the primary means for deter- mining whether immune-mediated destruction of red blood cells is contributing to a patient’s anemia
DAT
58
What class always fixes complement?
IgM
59
What does a positive DAT mean?
Confirms the presence of IgG or complement on RBCs in vivo
60
What is associated with binding of IgG or IgM on RBCs?
Immune-mediated hemolytic anemia
61
What does a positive DAT mean for an anemic patient who has not been recently transfused?
Autoimmune hemolytic anemia (AIHA)
62
What is an alloadsorption?
Using donor/reagent RBCs with known antigen phenotypes to adsorb patient's autoantibodies; adsorbing cells should not have the antigens against which the alloantibodies react
63
What is an autoadsorption?
Using patient's own RBCs to remove autoantibodies, and alloantibodies should not bind since patient should lack the corresponding antigen
64
What is the procedure to detect and identify alloantibodies for people NOT recently transfused?
Warm autoadsorption: patient serum and cells are incubated at 37C, then use patient's own cells to remove autoantibodies... leaving alloantibodies in the serum
65
What is the procedure to detect and identify alloantibodies for people that were recently transfused?
Alloadsorption
66
What is the cell selection for alloadsorption based on?
Based only on clinically significant antigens: D, C, E, c, e, K, Fya, Jka, Jkb, S, and s
67
What is the cell selection for alloadsorption based on?
Based only on clinically significant antigens: D, C, E, c, e, K, Fya, Jka, Jkb, S, and s
68
If there's no alloantibodies detected, what units can be transfused?
Random units of appropriate ABORh type can be used
69
Mediated by autoantibodies that react at 37C
WAIHA
70
What antibodies are associated with WAIHA?
IgG
71
What is the typical results of WAIHA?
Positive autocontrol, positive DAT, and positive antibody screen with all reacting at IAT
72
If there's clinically significant alloantibodies present, what units are tranfused?
Units should lack the corresponding antigen (because you don't want the alloantibodies to react with the corresponding antigens)
73
If the autoantibody has a clear specificity and patient has active hemolysis, what unit is transfused?
Units lacking the antigen
74
If the autoantibody has a broad specificity, what unit is tranfused?
Units are compatible with any alloantibodies detected
75
What WAIHA treatment is used for patients who have a positive initial response to steroids?
Splenectomy
76
What WAIHA treatment raises hematocrit levels and lowers retic count (=less RBC destruction) that's not transfusion?
Prednisone therapy
77
What WAIHA treatment decreases antibody production and removes a potent site of RBC destruction?
Splenectomy
78
What WAIHA treatment interferes with antibody synthesis?
Immunosuppressive drugs
79
What is the site of hemolysis for WAIHA?
Extravascular (no cell lysis)
80
What are the four classic mechanisms that have been proposed to cause drug-induced problems?
- Immune complexes
- Drug adsorption
- Membrane modification
- Autoantibody formation
81
When should DIIHA be suspected?
When there's hemolysis or a positive DAT for no other reason AND if there's a drug history
82
What causes DIHA (Drug-Induced Sensitization and Immune Hemolytic Anemia)?
Drugs or Immune complex mechanism
83
What happens during a DIIHA?
drugs combine with plasma proteins to form immunogens (IgG or IgM recognizes determinants on drug)
84
What happens when patient takes drugs after immunization?
Drug-antidrug complex may occur, leading to activation of complement cascade, leading to lysis
85
What hemolysis do patients with DIIHA present?
Acute intravascular hemolysis
86
What action should be taken for patients with DIIHA?
Withdraw the drug
87
What is the DAT and screen result in patients with DIIHA?
Positive DAT and negative screen
88
What happens during a drug adsorption mechanism?
Drugs bind firmly to proteins including proteins on the RBC membrane
89
What drug causes a positive DAT and may cause hemolytic anemia?
Cephalosporins
90
What happens during a membrane modification (non-immunologic protein adsorption)?
Uptake of immunoglobulins or complement components is not the result of Ag/Ab-reactions
91
Is there a treatment for membrane modification (non-immunologic protein adsorption)?
No
92
What does non-immunologic mean?
Antibodies with blood group specificities are not involved (so tests with patient's serum and eluate are negative)
93
What serological reactions are observed with drug-induced positive DATs?
- Immune complex
- Drug adsorption
- Drug-independent
- Membrane modification
- Methyldopa-induced
94
What induces the production of an autoantibody that recognizes the RBC antigens?
Aldomet
95
What is serologically indistinguishable from antibodies seen in WAIHA?
Autoantibodies produced because of aldomet (membrane modification)
96
Which mechanism is the only one that has positive eluates?
Methyldopa-induced
97
Are any cells tests for Membrane modifcations?
No, it's non-immunologic protein adsorption
98
What is the frequency of hemolysis for immune complex?
small doses of drugs may cause intravascular hemolysis
99
What is the frequency of hemolysis for drug adsorption?
3-4% get extravascular hemolysis
100
What is the frequency of hemolysis for membrane modifcation?
None; 3% develop positive DAT
101
What is the frequency of hemolysis for methyldopa-induced?
less than 1% develop hemolytic anemia that mimics WAIHA; 15% develop positive DAT
