Immune-Mediated Anemia Flashcards
What is agglutination?
When antibody binds to RBCs and causes them to form aggregates. Each antibody has two binding sides so it can easily aggregate with multiple antibodies and multipple RBCs
Differentiate a direct coombs test from an indirect coombs test.
Direct Antiglobulin: Dtects antibody present on patient’s RBC, the antigen must be present on the patients RBCs, this it ptRBC+anti-Ig
Indirect Antiglobulin: Dtects antibody present in patients serum, antigen is present on anyone’s RBC, this is pt SERUM + NORMAL RBC +anti-Ig
What must occur for a positive result vs. a negative result in a direct coombs
In direct coombs, there is coombs reagent bound to pt RBC, because the ragent is binding to and detecting the antibody that is bound to the antigens of the patients RBCs
-in negative direct there is no antibody binding, so coombs reagent is not bound to RBCs
What is a positive result in a indirect coombs test? what about a negative
In a positive result you would see the patients serum and their antibodies binding to a normal RBC and the coombs reagent would bind to this
Compare warm with cold agglutination
Warm is IgG where cold is IgM
- warm is used for inflammation and neoplasms
- cold is used for myocplasma pneumonia and B cell lymphoproliferative disorders
What would you expect to happen in a Coomb’s test where A/B/AB blood is put into serum with Anti-A or Anti-B antibodies?
For the following conditions, would you use cold or warm agglutination?
Idiopathic, Chronic inflammation, Mycoplasma pneumonia, Neoplasms, B cell lymphoproliferative disorder
Warm: Idiopathic, Chronic inflammation, Neoplasms
Cold: Idiopathic, Mycoplasma pneumonia, B cell lymphoproliferative disorder
Which of the following would you NOT expect to generate a positive antiglobulin test?
A.Drug-induced hemolytic anemia
B.Mismatched blood transfusion
C.Systemic lupus erythematosus
D.Paroxysmal nocturnal hemoglobinuria
E.Rheumatoid arthritis
D. Paroxysmal nocturnal hemoglobinuria, because is is not antibdoy driven, it is a complement disorder. All antiglobulin tests require antibody
Which of the following antibody isotypes will most likely bind ABO antigens?
A.IgA
B.IgD
C.IgE
D.IgG
E.IgM
E. IgM
Explanation: Since ABO antigens are carbohydrates, they will elicit a T cell-independet responses. The primary Ab’s produced in a T cell-independent response are IgM. B cells are dependent upon T cells for the induction of class switching
What would you expect the results of direct and indirect Coomb’s tests to be in a patient who was given a mismatched transfusion?
Pos/Pos
What does an increased MCV mean?
Mean that the BM is trying to pump out RBCs, response to anemia usually.
Explain the immunologic process that links the transfusion of mismatched blood to the backache and decrease in blood pressure.
IgM in the serum binding onto the patient’s RBCs leading the the activation of complement. Complement initiates inflammation, which increases vasopermability resulting in a drop in BP.
Which of the following antibody isotypes most readily crosses the placenta?
A.IgA
B.IgD
C.IgE
D.IgG
E.IgM
D. IgG
Which of the following proteins is responsible for transferring immunoglobulin across the placenta?
A.FcεRI
B.FcγRII
C.FcμR
D.FcRn
E.Poly-Ig receptor
D. FcRn
Which of the following biochemical moieties is IgG most likely to bind?
A.Carbohydrate
B.DNA
C.Lipid
D.Protein
D. Protein
What are the 2 examples of antibdoy binding without an antigen?
FcRn is neonates and FcepsilonR on mast cells
-The Fc-gamma-RII is the offswtich for B cells and requires antibody cross linking
What antibody would initiate a T cell dependent response?
IgG because it requires a class swithc, IgM would be T cell Independent becase no class switching,
IgG binds protein while IgM can bind carbohydrates
What are ABO antigens made of? What are Rh antigens made of?
ABO are cabrohydrates so IgM binds
Rh are protein is IgG binds
Which Rh gene is more immunogenic? Are most people Rh-pos or neg?
There are two closely linked Rg genes: D and CE, where D is more immunogenic so it is the one we are testing for.
Most people are Rh postive, so RhD postivie, only about 15% are Rh negative
When are you most concerned about a mother regarding Rh-type? What do you assume about the baby?
It is bad when the mother is Rh (-) and you assume the baby is Rh (+)
worry because mom will produce antibodies to the babies Rh antigen
What is Rh disease of the newborn called?
Hemolytic disase of the fetus and the newborn (HDFN)
-eryhtroblastosis fetalis
In a second preganancy with an Rh (-) mother and her previous baby was Rh(+), what will the result of a direct coombs be?
A direct coombs would be positive, because moms antibody would be stuck to the fetus RBC
What is Rhogam? Who is it given to? What is its mechanism of action?
Rhogam is IgG agasint Rho D, given to Rh (-) mothers
Rhogam binds fetal RBcs, inhibits B cells, and induces complement-mediated lysis of fetabl RBC in maternal circulation because it prevents the mother antibodies from being able to find to the fetabl RBC since Rhogam is already bound
In drug induced hemolytic anemia would what would the result of the direct and indirect coombs test be
?
Direct would be positive because there is antibody (drug) bound to RBCs
Indirect would be Negative because his serum will not bind normaly health RBC
What is the drug an example of in hemolytic anemia?
It is a hapen and is binding to the RBC, this causes the body to recognize this as foregin, make antibodies against it, and initate the destruction of RBCs
What are the results of direct and indirect results of
- Transufsion reaction
- Rh disase of the newborn
- autoimmune diseases
- Drug-induced hemolytic anemia
Transfusion, Rh disease of the newborn, and autoimmune disease are direct positive and indirect postivie
Drug-induced hemolytic anemia is direct postivie but indirect negative
It is not possible to have a direct negative and indirect positive
