Transplantation Immunology

Question 1

syngeneic graft

Answer 1

transplant between IDENTICAL twins

Question 2

allogeneic graft

Answer 2

transplant between genetically distinct individuals

Question 3

xenogeneic graft

Answer 3

transplant between different species

Question 4

cross-match test

Answer 4

the direct assessment of ABO/Rh compatibility in blood transfusion

Question 5

important factors for blood transfusions

Answer 5

*erythrocytes do NOT express HLA class I or II molecules
*BUT erythrocytes DO express ABO and rhesus (Rh) antigens

Question 6

what are the immunoglobulin class found in blood plasma (ABO) vs. Rh

Answer 6

ABO has IgM antibodies
Rh has IgG antibodies

Question 7

acute hemolytic transfusion reaction

Answer 7

*ABO group incompatibility causes host antibodies to attack transfused RBCs in a type II HSR
*presentation = fever, hypotension, tachypnea, tachycardia, hemoglobinuria, and jaundice WITHIN 1 HOUR OF TRANSFUSION

Question 8

transplant rejection - basics

Answer 8

HOST immune cells attack transplanted organ

Question 9

graft-versus-host disease - basics

Answer 9

TRANSPLANTED immune cells attack the host in a type IV HSR

Question 10

graft-vs-host disease - details

Answer 10

1. T cells are present in the graft
2. upon transplant, they travel to the lymph nodes of the host and proliferate
3. T cells attack “foreign” host cells and cause severe organ dysfunction

Question 11

graft-vs-host disease - presentation

Answer 11

maculopapular rash
jaundice
diarrhea
hepatosplenomegaly

Question 12

graft-vs-host disease - treatment

Answer 12

immune suppression (cyclofosamide after receiving the graft)

Question 13

graft-versus-host disease - grading

Answer 13

graded from I to IV, based on increasing RASH and DIARRHEA OUTPUT

Question 14

transplant rejection and histocompatibility antigens

Answer 14

recipient response against major AND minor histocompatibility antigens

Question 15

minor histocompatibility antigens

Answer 15

intracellular proteins that vary between individuals in a population

Question 16

alloantigens

Answer 16

term used to describe major and minor histocompatibility antigens together

Question 17

2 types of allorecognition

Answer 17

1. direct (MAJOR histocompatibility antigens)
2. indirect (MINOR histocompatibility antigens)

Question 18

hyperacute transplant rejection - timing

Answer 18

within minutes to an hour

Question 19

hyperacute transplant rejection - cause

Answer 19

pre-existing recipient antibodies react to donor antigens (often HLA)

Question 20

hyperacute transplant rejection - mechanism

Answer 20

antibodies deposit in vasculature of graft, leading to thrombosis and subsequent ischemia/necrosis of the graft

Question 21

hyperacute transplant rejection - treatment

Answer 21

removal of organ

Question 22

acute transplant rejection - timing

Answer 22

weeks to months (usually about 2 weeks)

Question 23

acute transplant rejection - cause

Answer 23

direct allorecognition: graft dendritic cells travel to host lymph nodes and activate HOST T cells against donor HLA

Question 24

acute transplant rejection - mechanism

Answer 24

T cells attack the vasculature of the graft, leading to vaculitis

Question 25

acute transplant rejection - treatment/prevention

Answer 25

immunosuppression and histocompatibility matching

Question 26

chronic transplant rejection - timing

Answer 26

months to years

Question 27

chronic transplant rejection - cause

Answer 27

indirect allorecognition: recipient APCs present donor intracellular peptides to activate host T cells and B cells

Question 28

chronic transplant rejection - mechanism

Answer 28

T cells secrete cytokines, leading to fibrosis and arteriosclerosis of graft

Question 29

hyperacute transplant rejection - HSR type

Answer 29

type II HSR (antibody-mediated)

Question 30

acute transplant rejection - HSR type

Answer 30

type IV HSR (T-cell mediated)

Question 31

chronic transplant rejection - HSR type

Answer 31

type II/IV HSR (antibodies and Th1 cells)