5. Histocompatibility refers to:
A. Matching of ABO antigens only
B. Degree of immunological compatibility between donor & recipient
C. Ability of RBCs to bind antibodies
D. Survival of the graft without immunosuppression only

B. Degree of immunological compatibility between donor & recipient

6. MHC haplotypes are inherited:
A. From the father only
B. From the mother only
C. As one haplotype from each parent
D. Randomly from both parents without linkage

C. As one haplotype from each parent

7. MHC matching is important because:
A. MHC is never recognized by T cells
B. MHC mismatch causes strong T-cell activation
C. MHC does not influence graft rejection
D. MHC is expressed only in RBCs

B. MHC mismatch causes strong T-cell activation

8. Blood transplantation is simpler than organ transplantation because:
A. RBCs lack MHC molecules
B. RBCs cannot activate complement
C. Cross-match testing is unnecessary
D. Antibodies do not bind RBCs

A. RBCs lack MHC molecules

9. Anti-A and anti-B antibodies arise because:
A. The mother passes them to the baby
B. Exposure to commensal bacterial carbohydrates that mimic A/B antigens
C. MHC-II presentation of food antigens
D. Autoimmune response

B. Exposure to commensal bacterial carbohydrates that mimic A/B antigens

10. The Rh factor refers to the presence of:
A. A/B antigens
B. MHC-I
C. The RhD antigen on RBCs
D. Complement receptors

C. The RhD antigen on RBCs

11. A cross-match test detects:
A. Donor T cells
B. Recipient complement levels
C. Pre-formed antibodies in the recipient against donor RBCs
D. MHC compatibility

C. Pre-formed antibodies in the recipient against donor RBCs

12. Hyperacute rejection is caused by:
A. T-cell activation against minor antigens
B. Pre-existing antibodies against donor ABO or MHC
C. Autoimmune antibodies
D. Slow chronic vascular changes

B. Pre-existing antibodies against donor ABO or MHC

13. Hyperacute rejection occurs within:
A. Minutes to hours
B. Days to weeks
C. Months to years
D. Only after immunosuppression

A. Minutes to hours

14. Acute rejection is primarily mediated by:
A. Autoantibodies
B. Complement alone
C. Recipient T cells recognizing donor MHC
D. Innate macrophage activation only

C. Recipient T cells recognizing donor MHC

15. Minor histocompatibility antigen mismatch leads to:
A. Rapid hyperacute rejection
B. No rejection
C. Slower, weaker T-cell responses
D. Antibody-mediated complement lysis only

C. Slower, weaker T-cell responses

16. Chronic rejection is characterized by:
A. Immediate thrombosis
B. Fibrosis and vessel narrowing over years
C. Massive cytokine storm within hours
D. Absence of immune activation

B. Fibrosis and vessel narrowing over years

17. BMT is different from solid organ transplant because the graft:
A. Contains no immune cells
B. Is immunologically inactive
C. Contains active donor immune cells that can attack the host
D. Cannot cause rejection

C. Contains active donor immune cells that can attack the host

18. Allogeneic transplantation involves:
A. Using the patient’s own stem cells
B. Using a genetically identical twin
C. Donor and recipient from the same species but genetically different
D. Donor cells from a different species

C. Donor and recipient from the same species but genetically different

19. Myeloablative therapy is used to:
A. Boost donor immunity
B. Destroy recipient bone marrow before transplant
C. Increase MHC expression
D. Suppress RBC production only

B. Destroy recipient bone marrow before transplant

20. Engraftment refers to:
A. Rejection of donor cells
B. Donor stem cells establishing in the recipient’s marrow
C. Removal of donor T cells
D. Development of hyperacute rejection

B. Donor stem cells establishing in the recipient’s marrow

21. A chimera is a transplant recipient who:
A. Has no donor cells
B. Has mixed donor–recipient immune systems
C. Rejects all grafts
D. Has only donor DNA

B. Has mixed donor–recipient immune systems

22. GVHD occurs because:
A. Recipient T cells attack the donor graft
B. Donor T cells attack recipient tissues
C. Antibodies attack donor RBCs
D. Neutrophils destroy donor HSCs

B. Donor T cells attack recipient tissues

23. GVHD most closely resembles which hypersensitivity type?
A. Type I
B. Type II
C. Type III
D. Type IV

D. Type IV

24. H-Y antigens are significant because:
A. They prevent GVHD
B. They are MHC-II molecules
C. They are male-specific minor antigens that female donors may react to
D. They cause hyperacute rejection

C. They are male-specific minor antigens that female donors may react to

25. GVHD can be beneficial because:
A. It suppresses the immune system completely
B. It provides a graft-versus-leukemia effect
C. It prevents chronic rejection
D. It eliminates the need for chemo

B. It provides a graft-versus-leukemia effect

26. HLA matching is more important in BMT than solid organ transplant because:
A. BMT lacks immune cells
B. Donor T cells interact strongly with recipient tissues
C. RBCs express HLA
D. Minor antigens do not matter in BMT

B. Donor T cells interact strongly with recipient tissues

27. General immunotherapies (e.g., steroids, calcineurin inhibitors):
A. Target very specific cytokines
B. Broadly suppress many immune pathways
C. Only suppress macrophages
D. Increase T-cell activation

B. Broadly suppress many immune pathways

28. Specific immunotherapies include:
A. Anti-IL-2 or anti-CD3 antibodies
B. Broad corticosteroids
C. Radiation therapy
D. Antibiotics

A. Anti-IL-2 or anti-CD3 antibodies

29. The purpose of immunosuppressive drugs is to:
A. Destroy the graft
B. Enhance MHC expression
C. Prevent rejection
D. Activate B cells

C. Prevent rejection

30. Immune-privileged sites include:
A. Skin
B. Eye, brain, testis, placenta
C. Liver and spleen
D. Lymph nodes

B. Eye, brain, testis, placenta

31. Combining HSC transplant with a solid organ transplant can:
A. Increase hyperacute rejection
B. Reset the immune system and promote tolerance to the organ
C. Prevent engraftment
D. Replace all recipient tissues entirely

B. Reset the immune system and promote tolerance to the organ

A 45-year-old woman receives a kidney transplant. Within 20 minutes, the kidney becomes cyanotic and stops producing urine. Biopsy shows widespread thrombosis and complement deposition.

Question:
What caused this reaction and how could it have been prevented?

Cause: Hyperacute rejection due to pre-formed antibodies against donor ABO or MHC antigens.
Prevention: Proper ABO matching and cross-match testing to detect pre-formed anti-donor antibodies.

A 28-year-old man receives a liver transplant. Two weeks later, liver enzymes rise and biopsy reveals T-cell infiltration.

Question:
What type of rejection is occurring, and what is the immunological basis?

Type: Acute rejection
Basis: Recipient T cells recognize donor MHC molecules, leading to a strong cell-mediated immune response.

A corneal transplant is performed without MHC matching or systemic immunosuppression. No rejection occurs.

Question:
Why?

The eye is an immune-privileged site, meaning immune responses are naturally limited, reducing graft rejection risk.

A 19-year-old patient undergoes allogeneic bone marrow transplantation for leukemia. Ten days later, she develops a maculopapular rash, severe diarrhea, and elevated liver enzymes.

Question:
What complication has occurred? What is the mechanism?

Complication: Graft-versus-host disease (GVHD)
Mechanism: Donor T cells attack recipient tissues, resembling Type IV hypersensitivity.