04 Immunology and Rejection Flashcards
(83 cards)
1
Q
The immune system recognizes the antigens of the new organ as…
A
non-self
2
Q
Auto-transplantation is…
A
- transplantation of self tissue.
- Not detected as a foreign body, no rejection. Ex. Own blood before surgery
3
Q
Iso-transplantation is…
A
- transplantation of tissue or organ between genetically identical individuals.
- Doesn’t activate immune response.
4
Q
Allotransplantation is…
A
- transplantation between genetically different people.
- This will trigger the immune response. Allograft.
5
Q
Xenotransplantation is…
A
transplant between two different species.
6
Q
The immune system protects us through these 3 actions…
A
- Surveillance
- Defense
- Homeostasis
7
Q
A humoral response involves…
A
the production of antibodies (immunoglobulins) by plasma cells (B-cells)
8
Q
A cellular response is…
A
communication between cells (lymphocytes). This leads to intracellular destruction of foreign cells (T-cells)
9
Q
Lymphocytes include…
A
- T cells
- B cells
10
Q
T cells are involved in these 3 processes…
A
- cell-mediated immunity, therefore responsible for cellular rejection
- Immature lymphocytes migrate through thymus to mature
- Differentiate to memory cells, cytotoxic cells, helper cells, suppressor cells
11
Q
B cells are involved in these 3 processes…
A
- humoral immune response, therefore responsible for humoral rejection (AMR)
- Immature lymphocytes migrate through bone marrow to mature
- Differentiate to memory cells, IgM, IgG, IgA, IgE (plasma cells)
12
Q
4 Characteristics of the immune system:
A
- Ability to recognize and eliminate foreign antigens
- Capacity for immunologic memory
- Distinct antigen specificities after immunizations
- Tolerance of self antigens
13
Q
Cytokines are characterized as these 7 actions…
A
- hormonal messengers
- Tells cells to proliferate in response to foreign cells
- Responsible for most of the biological effects in the immune system
- Cell-mediated immunity
- Allergic type responses
- T lymphocytes are a major source of cytokines
- Antigen-specific receptors on the cell surface allow recognition of foreign pathogens
14
Q
The Major Histocompatibility (MHC) System is characterized by these 4 elements…
A
- the system that drives rejection in allotransplantation
- In humans it is called human leukocyte antigen system (HLA)
- HLA antigens are proteins (or markers) on the surface of our cells and act as genetic identification
- Antigens are determined by two haplotypes and are inherited from biological parents
15
Q
HLA typing is characterized by these 3 aspects…
A
- how we define ourself immunologically
- it is based on our genetic inheritance
- it never changes
16
Q
A Haplotype is…
A
a series of HLA “genes” (loci-alleles) by chromosome, one passed from the mother and one from the father.
17
Q
The chance that two offspring will be HLA identical
A
25%
18
Q
The chance that two offspring will not share any alleles (HLA non-identical)
A
25%
19
Q
The chance that two offspring will share one haplotype
A
50%
20
Q
Outside an individual’s immediate family, the chance of finding an identical HLA match with the general population is
A
1:50,000
21
Q
HLA typing is done…
A
once. It never changes.
22
Q
HLA Antibody testing is done how frequently?
A
- Multiple times:
- Pre-Transplant
- Desensitization
- Post Transplant
23
Q
HLA Crossmatch is how frequently?
A
- At time of transplant (crossmatch with donor):
- Prospective
- Retrospective
- Virtual
24
Q
HLA Antibodies are classified as these 2 classes:
A
- Class I: on all cells
- Class II: on B cells
25
Rejection can occur despite HLA matches due to…
Many alles, splits and cregs
26
Antibodies can be effected by 5 sensitizing events:
* Blood products
* Pregnancy
* Transplant (any organ)
* Mechanical circulatory support
* Tissue graft
27
cPRA is defined as
* the percentage of potential donors a specific patient will have a positive crossmatch
* It is a calculation based on antigen frequency in a given population
28
The higher the cPRA, the…
harder it is to find a good match
29
In transplant, we pay attention to 6 loci within the HLA classes:
* Major MHC class I
* HLA-A
* HLA-B
* HLA-C
* Major MHC class II
* HLA-DP
* HLA-DQ
* HLA-DR
30
Within each of the 6 major loci, there are how many alleles?
hundreds of alleles (variations)
31
Serotyping is a ___________ way of identifying HLA receptors
crude
32
Phenotyping is a ______________ way of identifying HLA receptors
more specific
33
Regardless of your center's protocols, ALL crossmatches for purposes of the ABTC exam, must be…
NEGATIVE
34
Antibody screening is done in the ________________ (donor or recipient)
recipient
35
The frequency of antibody testing when there is no evidence of sensitization is…
every 6 months
36
The recommended frequency for antibody screening in patients with antibodies \>10% is…
monthly
37
The recommended frequency for antibody screening in LVAD recipients is …
monthly, may be more frequent
38
The recommended frequency for antibody screening with blood transfusions is…
1-2 weeks after the event
39
The recommended frequency for antibody screening after desensitization therapy is…
1 -2 weeks
40
The recommended frequency for antibody screening for all others (pediatric, retransplant, pregnant women) is …
every 3 months
41
A prospective crossmatch determines if the recipient has...
* Determines if the recipient has HLA antibodies to a particular donor
42
A prospective crossmatch physically does what?
Combines recipient serum and donor cells
43
In a prospective crossmatch if the test is positive, this is…
NOT good
44
In a virtual crossmatch the matching is done by...
the recipient's antibody profile is matched against the donor's HLA antigens
45
In a retrospective crossmatch, the matching is done at what time?
* Serum is drawn in the OR at the time of transplant. Crossmatch is determined immediately post transplant.
* Organ is already in when you get the crossmatch results. Have to be confident that you can manage a positive cross-match.
46
In a Complement-dependent cytotoxicity crossmatch (CDC), when Recipient serum potentially containing donor-specific antibodies (DSA) is added to donor T or B lymphocytes, along with complement,
If DSA is not present, what result do we see?
* no lysis occurs and the result is negative.
47
A Flow cytometry crossmatch is more sensitive compared with...
CDC cross- matching.
48
When you do a crossmatch, you want the recipient to have every antigen that the donor has.This is called...
zero mis-matches
49
T/F If the donor has an antigen that the recipient does not have you can accept the donor.
False: this would be a mis-match and you would NOT accept the donor.
50
Rh antigens are not present on lymphocytes and therefore they…
are NOT taken into account for organ transplant
51
Regarding ABO compatibility in infants under age 2,
ABO incompatible hearts may be accepted.
52
A Direct Coombs Test tests an infant's Rh. Rh factor __________ considered when accepting an organ offer
is NOT
53
A blood type O recipient will be compatible with a donor blood type…
O
54
A blood type A recipient will be compatible with a donor blood type…
O, A
55
A blood type B recipient will be compatible with a donor blood type…
O, B
56
A blood type AB recipient will be compatible with a donor blood type…
O, A, B, AB
57
A blood type O donor will be compatible with a recipient blood type…
O, A, B, AB
58
A blood type A donor will be compatible with a recipient blood type…
A, AB
59
A blood type B donor will be compatible with a recipient blood type…
B, AB
60
A blood type AB donor will be compatible with a recipient blood type…
AB
61
4 Types of Rejection include...
* Hyperacute (antibody-mediated)
* Antibody-mediated rejection (AMR) or humoral
* Acute- cellular
* Chronic (Obliterative Bronchiolitis, Coronary artery vasculopathy, vanishing bile ducts)
62
Hyperacute Rejection is characterized by these 10 things:
* \< 1% incidence (role of cross-match)
* Minutes to days onset
* Abrupt organ dysfunction
* Blood group mismatch
* Preformed circulating Abs
* - complement activation
* - endothelial damage, inflammation
* - platelet aggregation
* Vascular thrombosis
* Support (such as ECMO) and possible relist for transplant
63
Antibody Mediated Rejection is characterized by these 3 things:
* Mediated by B cell antibodies and characterized by vascular inflammation and damage
* Diagnosed by immunofluorescence stain of biopsy tissue and reveals immunoglobulin deposits (IgM, IgG) C3d, C4d, CD68 stains
* Antibodies to donor specific antigens
64
AMR Biopsy terminology (histology) includes these 6 terms:
* Intravascular macrophages
* Capillary destruction
* Edema
* Hemorrhage
* Neutrophilic infiltrates
* Capillary fragmentation
65
AMR Immunopathology potentially includes the use of these 6 immunofluorescencea:
* C3d
* C4d
* HLA
* Ig
* Fibrin
* Cd20
66
6 potential AMR Treatments: When Asymptomatic includes…
* Monitor (pAMR1)
* no Rx
* hold steroid taper
* ∆ maintenance immunosuppression
* (MMF/FK)
* monitor DSA/pathology findings
67
5 potential AMR Treatments when Mild Symptoms includes...
* high dose (pulse) steroids
* thymoglobulin (rabbit ATG)
* +/- IV immune globulin
* ∆ maintenance immunosuppression (
* MMF/FK)
68
7 potential AMR Treatments when hemodynamically compromised includes...
* high dose (pulse) steroids
* plasmapheresis/apheresis
* +/- IV immune globulin
* thymoglobulin (rabbit ATG)
* “newer” therapies (rituximab, etc.)
* ∆ maintenance immunosuppression
* (MMF/FK)
69
The most common form of rejection is…
Acute Cellular Rejection (\>10%)
70
Acute Cellular Rejection takes place…
Weeks to months post-transplant
71
Acute cellular rejection is caused by a…
Cytokine-induced vascular leak
72
A biopsy for acute cellular rejection may indicate any of these 4 items:
* Endothelialitus
* parenchymal cell damage
* interstitial inflammation
* Edema and mild hemorrhage
73
In determining acute cellular rejection, PRA screening is not predictive of...
NOT predictive of cell injury and graft ischemia
74
Treatment for acute cellular rejection includes…
high dose steroids, optimizing drug levels
75
Chronic Rejection takes place…
Months to years onset
76
Chronic Rejection is characterized by these 3 things:
* Gradual decline in organ function
* Chronic healing and scarring Intimal smooth muscle cell proliferation
* Vascular (or airway or biliary) dense fibrosis (ischemia)
77
Chronic rejection will usually require…
Re-transplant
78
6 Signs of Rejection Liver include:
* Elevated liver enzymes
* Tenderness over liver
* Yellow color to eyes or skin
* Dark urine
* Ascites
* Fever
79
6 Signs of Rejection Kidney Include:
* Elevated BUN, creatinine
* Decreased urine output
* Weight gain
* Pain at kidney site
* Leg swelling
* Fever
80
7 Signs of Rejection Heart include:
* Irregular heartbeat
* Very fast or very slow heart rate
* Low BP
* Shortness of breath
* Weight gain
* Tiredness
* Fever
81
5 Signs of Rejection Lung include:
* Shortness of breath
* Tiredness
* Productive cough
* Change in color of sputum
* Fever
82
Signs of Rejection Pancreas include:
High blood glucose levels
83
6 Signs of Rejection Intestines include:
* Change in stool output
* Tiredness
* abdominal pain or distention
* dusky stoma
* weight loss
* Fever
