Type II Hypersensitivity Flashcards
Type II hypersensitivity is also known as _____________ hypersensitivity
Cytotoxic
What are the three main diseases that cause Type II Hypersensitivity reactions?
- Transfusion reactions
- Hemolytic disease of the newborn
- Reactions to drugs or infectious agents
What species has the most diverse blood system?
Cows- 11 blood groups
What species has the least diverse blood system?
Cats- 1 major blood group
True/False: Antigens are MHC molecules
False!!
Describe the typical antigen
membrane-bound or soluble?
composition
function
Most are surface antigens, some are soluble
Most are glycoproteins or associated glycolipids
they serve to transport different molecules
What are natural antibodies? How are they generated?
Antibodies to blood group antigens that are not expressed in that individual and that they have never been exposed to.
Why are natural antibodies of concern in transfusion medicine?
If exposed to antigens of this type, a transfusion reaction will occur either against the host or against the donor blood.
How can drugs and immune clearance of infectious organisms induce a Type II hypersensitivity reaction?
immune clearance- antibodies againts infectious organisms can also croos react with RBC antigens
drugs- bind/absorb onto RBC and then are seen as foreign; can activate complement resulting in a destructive immune response against RBCs
What type of T helper cell response is involved with an antibody response?
Th2
What two types of mechanisms are associated with Type II Hypersensitivity?
- Complement mediated lysis
2. Cell-mediated killing
In HDN/NI, what three mechanisms sensitize the mother to foreign red blood cells?
- Leakage of fetal RBC across the placenta
- Previous receipt of an incomplete transfusion
- Development of cross reactive antigens
Where are antibodies against fetal RBCs concentrated?
Colostrum
What happens when a foal receives anti-RBC antibodies in the colostrum?
Antibodies cross the GI mucosa and begin to attack neonatal RBCs-> rapid onset of hemolysis
What is neonatal thrombocytopenia?
similar to HDN/NI, except the antibodies are against platelets and not red blood cells
What antibodies is usually present with transfusion reactions?
IgM
What usually happens with a first-time transfusion reaction?
antibodies will be generated against the red cells over time. Transfused red blood cells will circulate until antibodies are developed and then the cells will undergo antibody mediated destruction
What are two methods to prevent transfusion reactions?
- Blood typing
2. Cross matches
What is agglutination?
Agglutination is grape-like clustering of erythrocytes to antibody crosslinking
Which antibody is good at agglutination and which is not?
IgM-good
IgG-bad
What is blood typing?
This is performed by mixing washed RBCs from a patient with species specific antiserum (antibodies). If the antiserum cross reacts with the patient RBCs, RBCs will agglutinate.
What is a major cross match? What is a minor cross match?
Major Cross Match- donor cells with recipient serum. Detects antibodies in the animal that can react against transfused blood.
Minor Cross Match- recipient cells with donor serum
Detects antibodies in the donor blood that can react against the donor blood
Match the species with the most clinically relevant blood group system Cat A&Q Cow B&J Dog B&R Horse DEA 1.1 Pig A&O Sheep AB
Cat-AB Cow- B&J Dog-DEA 1.1 Horse- A&Q Pig- A&O Sheep- B&R
Mix and Match
Cat Every one has unique blood panel
Cow Minimal donor-1.1 negative
Dog One RBC Ag is K+ porter
Horse HDN/NI assoc w/ RBC in vaccines
Pig One blood group system
Sheep HDN/NI very common
Cat- One blood group system Cow- Every one has unique blood panel Dog- Minimal donor- 1.1 negative Horse- HDN/NI is very common Pig- HDN/NI associated with RBC in vaccines Sheep- One RBC Ag is K+ porter
