Introduction to Transplantation Immunology Flashcards Preview

MSS-IHL Final Exam > Introduction to Transplantation Immunology > Flashcards

Flashcards in Introduction to Transplantation Immunology Deck (30):
1

syngenic

transplantation between genetically identical individuals

2

allogenic

transplantation between genetically dissimilar individuals of same species

3

xenogeneic

transplantation between different species

4

minor histocompatability antigen

normal proteins on cell surface that are polymorphic in nature

5

evidence that graft rejection is caused by lymphocytes

occurs 7-14 days after first transplant
-role of lymphocytes

rejection occurs more rapidly second time
-role of memory

rejection of distinct graft 7-14 days
-specific response

6

evidence for role of MHC in grafts?

transplant between genetically identical individuals not rejected

transplant between genetically non-identical individuals is rejected

7

direct alloantigen recognition

allogenic APC presents allogenic MHC

**activates CTLs

8

indirect alloantigen recognition

self APCs present allogenic MHC proteins

**activates CD4 T cells

can also have allo-antibodies produced by alloreactive B cells in indirect pathway

9

high probability that T cells recognize allogenic MHC due to?

T cells are selected to have low affinity
-allogenic MHC not negatively selected - may be high affinity

self MHC restricted T cells are able to recognize foreign MHC

allogenic MHC with bound peptide may mimic self MHC and peptide complex

10

what trigger costimulation expression in transplantation patients?

fuck

11

hyperacute rejections

within minutes
thrombosis of graft vessels followed by ischemic necrosis

host circulating antibodies are specific for antigens on graft endothelial cells

complement activation leads to endothelial cell injury

thrombosis and vascular occlusion occur

12

how to prevent hyperacute?

cross-match with antibodies

13

acute rejection

within days to weeks
rejection timulated by alloantigens in the graft

mechanism:
-acute cellular rejection (CTL and CD4)
-microvascular endothelialitis
-acute antibody-mediated rejection characterized by transmural necrosis of graft vessel walls

14

acute rejection treatable?

YES!

15

chronic rejection

months to years after transplant

T cells and antibodies against alloantigens

immune response results in fibrosis of graft tissue and gradual narrowing of vessels
-graft arteriosclerosis

16

immunosuppressive drugs for T cells used in transplantation

azathioprine, rapamycin, cyclosporine, anti-IL-2R, anti-TCR (OKT3, thymoglobulin)

17

rapamycin

targets mTORC1

18

azathioprine

no proliferation

19

cyclosporine

inhibits calcineurin

important one**

20

CTLA4-Ig

inhibits CD28 B7 interaction

21

thymoglobulin, OKT3

no TCR activation

22

side effects of immunosuppression

malignancy
infections
drug toxicity

23

non T cell targets for immunosuppression

alloantibodies and alloreactive B cells

anti-inflammatory drugs

inhibitors of leukocyte migration

24

strategy to minimize alloantigenic effects?

cross-matching
-testing for preformed antibodies against donor HLA

25

why do people develop anti-A and anti-B antibodies for blood group antigens?

normal gut flora has similar epitopes

26

lewis antigen

fucosylation at additional terminal sites of blood group antigen

27

rhesus antigen

Rh

15% of population has deletion or other alteration in RHd allele

28

Can ABO-incompatible transplant be done?

???/

29

GVHD

graft versus host disease

reaction of mature grafted T cells to alloantigens of the host

usually against minor histocompatability antigens

acute less than 100 days
chronic greater than 100 days

treated by immunosuppression

30

hematopoietic stem cell transplant

transfer allogenic pluripotent hematopoietic stem cells

patient treated with radiation to deplete bone marrow