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COM MOD > Chapter 6- Rejection of Tissue Transplant > Flashcards

Chapter 6- Rejection of Tissue Transplant Flashcards

1
Q

Process of Rejection

A

T cells and antibodies produced against graft antigens react against and destroy tissue graft

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2
Q

Where are major antigenic differences between the donor and the recipient?

A

HLA alleles

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3
Q

Characteristics of HLA genes

A

highly polymorphic

always some differences between individuals

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4
Q

Allografts

A

same species

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5
Q

Xenografts

A

grafts from one species to another

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6
Q

2 types of T-Cell Mediated Reactions

A

Acute cellular rejection, chronic rejection

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7
Q

When does Acute Cellular Rejection occur?

A

initial months after transplantation

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8
Q

Clinical signs of acute cellular rejection

A

organ failure

increased vascular permeability and local accumulation of mononuclear cells

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9
Q

What cells secrete cytokines during acute cellular rejection

A

activated CD4+ T cells

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10
Q

What occurs during chronic rejection

A

lymphocytes react against alloantigens in vessel wall

cytokines released to induce local inflammation

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11
Q

3 types of Antibody-Mediated Reactions

A

hyperacute, acute antibody-mediated, chronic antibody-mediated rejection

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12
Q

How does hyperacute antibody-mediated rejection occur?

A

preformed antidonor antibodies are present in circulation of recipient

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13
Q

Why would a recipient have preformed antidonor antibodies?

A

From previous transplant, prior blood transfusions, and multiparous women

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14
Q

How does acute antibody-mediated rejection occur?

A

Antidonor antibodies produced after transplantation

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15
Q

What is the initial target of antidonor antibodies in acute antibody-mediated rejection?

A

graft vasculature

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16
Q

How does chronic antibody-mediated rejection occur?

A

gradual development

affects vascular components

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17
Q

Methods of Increasing Graft Survival (5)

A 
HLA matching
Immunosuppressive therapy
T cell and B cell depleting antibodies
Pooled intravenous IgG
Plasmapheresis
18
Q

How does HLA matching increase graft survival in kidney transplants?

A

benefit if all polymorphic HLA alleles are matched

19
Q

What organs is HLA matching not done?

A

liver, heart, lungs

20
Q

What immunosuppressive therapies are used to increase graft survival?

A

steroids to reduce inflammation
mycophenolate mofetil to inhibit lymphocyte proliferation
Tacrolimus to inhibit T cell function

21
Q

Risk of using immunosuppressive therapy

A

increased risk of infections

22
Q

How does pooled intravenous IgG increase graft survival?

A

suppresses inflammation

23
Q

When is plasmapheresis used?

A

severe antibody-mediated rejection

24
Q

Polyoma virus

A

reactivates when a person is too immunosuppressed

infects renal tubules

25
Q

Immunosuppression and Increased Latent Viruses

A

increased risk for re-activation of latent viruses
EBV-induced lymphomas
HPV
Kaposi sarcoma

26
Q

What is a bone marrow transplant?

A

transplantation of hematopoietic stem cells

27
Q

What is a HSC transplant used for? (3)

A

hematologic malignancies
bone marrow failure syndromes
inherited stem cell defects

28
Q

Bone marrow failure syndrome

A

aplastic anemia

29
Q

Inherited Stem Cell defects

A

sickle cell anemia
thalassemia
immunodeficiency states

30
Q

Where do transplanted HSC cells come from? (2)

A

Peripheral blood after they are mobilized from bone marrow after given hematopoietic growth factors
Umbilical cord form newborn

31
Q

How does the recipient allow transplanted stem cells to engraft?

A

recipient treated with high doses of chemotherapy to destroy immune system

32
Q

When does Graft-vs-Host Disease occur?

A

transferred cells from donor recognize alloantigens in recipient and attack the host cells

33
Q

When is GVHD most seen?

A

in HSC transplantation

34
Q

When is GVHD rarely seen?

A

in transplantation of solid organs rich in lymphoid cells or transfusion of unirradiated blood
ex. liver

35
Q

How to minimize GVHD

A

HLA-matching

36
Q

When does acute GVHD occur?

A

within days/weeks/couple months after bone marrow transplantation

37
Q

What clinical manifestations occur with GVHD? (4)

A

immune system, skin (rash), liver (jaundice), intestine (diarrhea)

38
Q

What occurs during chronic GVHD? (4)

A

cutaneous injury, chronic liver disease, damage to GI tract, immune system devastated

39
Q

Immune system in chronic GVHD

A

shrinking of thymus, depletion of lymphocytes in lymph nodes

recurrent and life-threatening infections

40
Q

What mediates GVHD?

A

T lymphocytes in the transplanted donor cells

*depletion of T cells may eliminate GVHD

41
Q

Risks for depleting T cells to help GVHD (3)

A

recurrent tumors in leukemic patients
increased graft failures
increased risk of EBV related B cell lymphoma

COM MOD (21 decks)

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