AACE CCT Primer Questions With Complete
Solutions. 2026/2027
Comprehensive Certification Examination - 150 Questions
Aligned with AACE (American Association of Clinical Endocrinologists) CCT (Certified Clinical
Transplant) Certification Standards, Transplant Coordination Competencies, and Clinical Transplant
Practice Guidelines (2026/2027 Edition).
Reference standards include OPTN/UNOS Policies, Banff Classification, KDIGO Guidelines, ISHLT
Guidelines, AST/ASTS Clinical Practice Guidelines, and CMS Conditions of Participation.
Exam Composition: 150 Questions across 8 sections (Immunology 20 · Pre-Transplant Evaluation 25 ·
Allocation & UNOS/OPTN 20 · Donor Management 15 · Immunosuppression 20 · Post-Transplant Care 25 ·
Rejection & Monitoring 15 · Psychosocial/Ethical 10).
Cognitive Mix: 25% Recall · 50% Application · 25% Analysis. Format: 75% Scenario-Based · 25% Direct
Knowledge.
Section 1: Transplant Immunology & Basic Science
Q1: A 45-year-old male with ESRD receives a deceased-donor kidney transplant. Within
minutes of reperfusion, the graft turns flaccid and purple. The underlying mechanism of
this hyperacute rejection is mediated by:
A. Preformed recipient IgG antibodies against donor HLA or ABO antigens activating
complement [CORRECT]
B. Cytotoxic T lymphocytes recognizing donor MHC class I on graft endothelium
C. Donor T cells attacking recipient tissues via cytokine storm
D. Chronic fibrosis and intimal hyperplasia of graft vasculature
Correct Answer: A
Rationale: Hyperacute rejection occurs within minutes to hours of reperfusion and is mediated by
preformed recipient antibodies (anti-HLA, anti-ABO, or anti-endothelial) that bind donor endothelium,
activate complement, and cause immediate thrombosis and graft necrosis. AACE CCT standards require
coordinators to recognize this as a CDC crossmatch indication and an absolute contraindication to
transplantation. CTL-mediated rejection (B) is acute cellular rejection; GVHD (C) is the opposite direction;
chronic rejection (D) develops over months to years.
,Q2: A transplant candidate has a Panel Reactive Antibody (PRA) of 85%. Which of the
following statements best reflects the clinical implications under the current kidney
allocation system (KAS)?
A. PRA of 85% corresponds to a CPRA of 85%, granting priority points and requiring a negative
crossmatch before transplant. [CORRECT]
B. PRA of 85% indicates the patient has an 85% chance of acute cellular rejection in the first
year.
C. PRA of 85% means the candidate is ineligible for transplantation due to antibody burden.
D. PRA of 85% only reflects IgM antibodies and has no clinical significance in allocation.
Correct Answer: A
Rationale: PRA (historically) and CPRA (Calculated PRA, current standard) reflect the percentage of
donors against whom the candidate has anti-HLA antibodies. A CPRA of 85% grants sliding-scale priority
points under KAS to compensate for the difficulty of finding a compatible donor, and a negative flow or
CDC crossmatch is required before transplant. PRA/CPRA does not predict cellular rejection (B), does not
contraindicate transplantation (C), and clinically significant antibodies are IgG class (D).
Q3: A complement-dependent cytotoxicity (CDC) crossmatch is performed using recipient
serum against donor T and B lymphocytes. A positive T-cell CDC crossmatch with a negative
B-cell CDC crossmatch most likely indicates:
A. Preformed IgG antibodies against donor HLA class I antigens [CORRECT]
B. Preformed IgG antibodies against donor HLA class II antigens only
C. Autoantibodies against donor B cells
D. A false-positive result due to IgM interference
Correct Answer: A
Rationale: T lymphocytes express HLA class I but not class II, while B lymphocytes express both. A
positive T-cell CDC crossmatch indicates class I donor-specific antibodies, which is an absolute
contraindication to transplantation. A B-cell-only positive crossmatch (with negative T-cell) often suggests
class II antibodies (B), which may be acceptable in selected cases under AACE CCT guidance. IgM
autoantibodies (C, D) typically cause false-positive B-cell crossmatches, not T-cell.
Q4: Which of the following best describes the mechanism of T-cell costimulation blockade
by belatacept, an agent used in kidney transplant recipients?
A. Binds CD80/CD86 on antigen-presenting cells, blocking CD28-mediated costimulation
[CORRECT]
B. Binds CD40 on APCs, blocking CD40-CD154 interaction
C. Inhibits calcineurin, preventing IL-2 transcription
D. Inhibits mTOR, blocking T-cell proliferation downstream of IL-2
Correct Answer: A
Rationale: Belatacept is a fusion protein (CTLA4-Ig) that binds CD80/CD86 (B7-1/B7-2) on
antigen-presenting cells, blocking the CD28 costimulatory signal required for full T-cell activation. It is
approved as a CNI-sparing maintenance agent in kidney transplant per AACE CCT pharmacology
standards. CD40 blockade (B) is being investigated; calcineurin inhibition (C) is the mechanism of
tacrolimus/cyclosporine; mTOR inhibition (D) is the mechanism of sirolimus/everolimus.
,Q5: A lung transplant recipient develops acute cellular rejection confirmed by
transbronchial biopsy showing perivascular lymphocytic infiltrates. Which immunologic
effector cells are the primary mediators of this rejection?
A. CD8+ cytotoxic T lymphocytes and CD4+ helper T cells [CORRECT]
B. Donor B cells producing alloantibodies
C. Natural killer cells mediating antibody-independent cytotoxicity
D. Eosinophils and mast cells mediating type I hypersensitivity
Correct Answer: A
Rationale: Acute cellular rejection is primarily T-cell-mediated, involving CD8+ cytotoxic T cells that
recognize donor MHC class I and CD4+ helper T cells that orchestrate cytokine-driven inflammation and
recruit macrophages. Banff classification of acute rejection grades perivascular and peribronchiolar
mononuclear infiltrates. B cells (B) mediate antibody-mediated rejection, not cellular rejection. NK cells
(C) participate in ADCC but are not the primary effector in acute cellular rejection; eosinophils/mast cells
(D) are not central to allograft rejection.
Q6: In the context of antibody-mediated rejection (AMR), which of the following histologic
findings is most specific for AMR according to the Banff classification?
A. C4d deposition in peritubular capillaries with microvascular inflammation and circulating
donor-specific antibodies [CORRECT]
B. Interstitial edema with diffuse neutrophilic infiltrate
C. Tubulitis with CD3+ lymphocyte infiltration
D. Glomerular sclerosis and interstitial fibrosis with tubular atrophy
Correct Answer: A
Rationale: Per Banff criteria, AMR is diagnosed by the triad of: (1) histologic evidence of microvascular
inflammation (glomerulitis, peritubular capillaritis), (2) evidence of antibody-endothelium interaction
(C4d positivity in peritubular capillaries or moderate microvascular inflammation), and (3) serologic
evidence of donor-specific antibodies. C4d is the degradation product of C4b and serves as a footprint of
classical complement activation. Neutrophilic infiltrate (B) suggests pyelonephritis; tubulitis (C) is acute
cellular rejection; chronic changes (D) reflect chronic allograft injury.
Q7: A 50-year-old female receiving a hematopoietic stem cell transplant from an
HLA-identical sibling develops a maculopapular rash, diarrhea, and elevated liver enzymes
three weeks post-transplant. The immunologic mechanism of this graft-versus-host disease
(GVHD) involves:
A. Donor T cells recognizing recipient alloantigens on host tissues [CORRECT]
B. Recipient T cells attacking donor hematopoietic cells
C. Preformed recipient antibodies against donor HLA
D. Complement-mediated lysis of donor stem cells
Correct Answer: A
Rationale: GVHD occurs when donor immunocompetent T cells recognize recipient alloantigens
(especially minor histocompatibility antigens) on host tissues, leading to inflammation of skin,
gastrointestinal tract, and liver - the classic target organs. It is most common after hematopoietic stem cell
transplant but rarely reported after solid organ transplant (especially liver and intestine). Recipient attack
on donor cells (B) is rejection; antibody-mediated (C) and complement-mediated (D) mechanisms describe
hyperacute rejection, not GVHD.
, Q8: Which cytokine, primarily produced by activated CD4+ Th1 cells, is essential for the
proliferation and differentiation of cytotoxic T lymphocytes and is also the target of
calcineurin inhibitor therapy?
A. Interleukin-2 (IL-2) [CORRECT]
B. Interleukin-4 (IL-4)
C. Interleukin-10 (IL-10)
D. Transforming growth factor-beta (TGF-β)
Correct Answer: A
Rationale: IL-2 is the master growth factor for T cells, driving proliferation and differentiation of CTLs.
Calcineurin inhibitors (tacrolimus, cyclosporine) block IL-2 transcription by preventing NFAT nuclear
translocation, thereby suppressing T-cell activation - the cornerstone of maintenance
immunosuppression per AACE CCT standards. IL-4 (B) drives Th2 differentiation; IL-10 (C) is
immunosuppressive; TGF-β (D) promotes Tregs and fibrosis but is not the primary target of CNIs.
Q9: A transplant immunology laboratory reports a candidate's HLA typing as A*02:01,
A*24:02; B*07:02, B*35:01; DRB1*01:01, DRB1*03:01. In deceased-donor kidney allocation
under KAS, which loci are given primary weight for matching?
A. HLA-A, HLA-B, and HLA-DR (6-antigen match) [CORRECT]
B. HLA-C and HLA-DQ only
C. HLA-DP and HLA-DR
D. ABO blood group only
Correct Answer: A
Rationale: Under the original KAS framework, HLA-A, HLA-B, and HLA-DR (six antigens total) were the
primary loci used for allocation priority; a zero-mismatch (6-antigen match) kidney received highest
priority. The 2014 KAS revision maintained these loci for matching while introducing CPRA-based priority
and longevity matching (EPTS top 20% with top 50% ECD kidneys). HLA-C, DQ, and DP are not currently
used for allocation priority but are increasingly recognized for their role in DSA formation and AMR. ABO
compatibility is required but does not drive allocation priority except for pediatric priority.
Q10: Complement activation via the classical pathway in antibody-mediated rejection
culminates in the formation of which key effector complex that directly damages graft
endothelium?
A. Membrane attack complex (C5b-9) [CORRECT]
B. C3 convertase (C4b2a)
C. C1qrs complex
D. Properdin (factor P)
Correct Answer: A
Rationale: The classical complement pathway in AMR is activated when recipient IgG binds donor HLA on
endothelium, recruiting C1q, C4, and C2 to form the C3 convertase (C4b2a). Downstream, C5 is cleaved,
and C5b-9 (the membrane attack complex, MAC) is assembled, forming transmembrane pores that lyse
endothelial cells. C3 convertase (B) and C1qrs (C) are upstream intermediates; properdin (D) stabilizes the
alternative pathway C3 convertase.
Solutions. 2026/2027
Comprehensive Certification Examination - 150 Questions
Aligned with AACE (American Association of Clinical Endocrinologists) CCT (Certified Clinical
Transplant) Certification Standards, Transplant Coordination Competencies, and Clinical Transplant
Practice Guidelines (2026/2027 Edition).
Reference standards include OPTN/UNOS Policies, Banff Classification, KDIGO Guidelines, ISHLT
Guidelines, AST/ASTS Clinical Practice Guidelines, and CMS Conditions of Participation.
Exam Composition: 150 Questions across 8 sections (Immunology 20 · Pre-Transplant Evaluation 25 ·
Allocation & UNOS/OPTN 20 · Donor Management 15 · Immunosuppression 20 · Post-Transplant Care 25 ·
Rejection & Monitoring 15 · Psychosocial/Ethical 10).
Cognitive Mix: 25% Recall · 50% Application · 25% Analysis. Format: 75% Scenario-Based · 25% Direct
Knowledge.
Section 1: Transplant Immunology & Basic Science
Q1: A 45-year-old male with ESRD receives a deceased-donor kidney transplant. Within
minutes of reperfusion, the graft turns flaccid and purple. The underlying mechanism of
this hyperacute rejection is mediated by:
A. Preformed recipient IgG antibodies against donor HLA or ABO antigens activating
complement [CORRECT]
B. Cytotoxic T lymphocytes recognizing donor MHC class I on graft endothelium
C. Donor T cells attacking recipient tissues via cytokine storm
D. Chronic fibrosis and intimal hyperplasia of graft vasculature
Correct Answer: A
Rationale: Hyperacute rejection occurs within minutes to hours of reperfusion and is mediated by
preformed recipient antibodies (anti-HLA, anti-ABO, or anti-endothelial) that bind donor endothelium,
activate complement, and cause immediate thrombosis and graft necrosis. AACE CCT standards require
coordinators to recognize this as a CDC crossmatch indication and an absolute contraindication to
transplantation. CTL-mediated rejection (B) is acute cellular rejection; GVHD (C) is the opposite direction;
chronic rejection (D) develops over months to years.
,Q2: A transplant candidate has a Panel Reactive Antibody (PRA) of 85%. Which of the
following statements best reflects the clinical implications under the current kidney
allocation system (KAS)?
A. PRA of 85% corresponds to a CPRA of 85%, granting priority points and requiring a negative
crossmatch before transplant. [CORRECT]
B. PRA of 85% indicates the patient has an 85% chance of acute cellular rejection in the first
year.
C. PRA of 85% means the candidate is ineligible for transplantation due to antibody burden.
D. PRA of 85% only reflects IgM antibodies and has no clinical significance in allocation.
Correct Answer: A
Rationale: PRA (historically) and CPRA (Calculated PRA, current standard) reflect the percentage of
donors against whom the candidate has anti-HLA antibodies. A CPRA of 85% grants sliding-scale priority
points under KAS to compensate for the difficulty of finding a compatible donor, and a negative flow or
CDC crossmatch is required before transplant. PRA/CPRA does not predict cellular rejection (B), does not
contraindicate transplantation (C), and clinically significant antibodies are IgG class (D).
Q3: A complement-dependent cytotoxicity (CDC) crossmatch is performed using recipient
serum against donor T and B lymphocytes. A positive T-cell CDC crossmatch with a negative
B-cell CDC crossmatch most likely indicates:
A. Preformed IgG antibodies against donor HLA class I antigens [CORRECT]
B. Preformed IgG antibodies against donor HLA class II antigens only
C. Autoantibodies against donor B cells
D. A false-positive result due to IgM interference
Correct Answer: A
Rationale: T lymphocytes express HLA class I but not class II, while B lymphocytes express both. A
positive T-cell CDC crossmatch indicates class I donor-specific antibodies, which is an absolute
contraindication to transplantation. A B-cell-only positive crossmatch (with negative T-cell) often suggests
class II antibodies (B), which may be acceptable in selected cases under AACE CCT guidance. IgM
autoantibodies (C, D) typically cause false-positive B-cell crossmatches, not T-cell.
Q4: Which of the following best describes the mechanism of T-cell costimulation blockade
by belatacept, an agent used in kidney transplant recipients?
A. Binds CD80/CD86 on antigen-presenting cells, blocking CD28-mediated costimulation
[CORRECT]
B. Binds CD40 on APCs, blocking CD40-CD154 interaction
C. Inhibits calcineurin, preventing IL-2 transcription
D. Inhibits mTOR, blocking T-cell proliferation downstream of IL-2
Correct Answer: A
Rationale: Belatacept is a fusion protein (CTLA4-Ig) that binds CD80/CD86 (B7-1/B7-2) on
antigen-presenting cells, blocking the CD28 costimulatory signal required for full T-cell activation. It is
approved as a CNI-sparing maintenance agent in kidney transplant per AACE CCT pharmacology
standards. CD40 blockade (B) is being investigated; calcineurin inhibition (C) is the mechanism of
tacrolimus/cyclosporine; mTOR inhibition (D) is the mechanism of sirolimus/everolimus.
,Q5: A lung transplant recipient develops acute cellular rejection confirmed by
transbronchial biopsy showing perivascular lymphocytic infiltrates. Which immunologic
effector cells are the primary mediators of this rejection?
A. CD8+ cytotoxic T lymphocytes and CD4+ helper T cells [CORRECT]
B. Donor B cells producing alloantibodies
C. Natural killer cells mediating antibody-independent cytotoxicity
D. Eosinophils and mast cells mediating type I hypersensitivity
Correct Answer: A
Rationale: Acute cellular rejection is primarily T-cell-mediated, involving CD8+ cytotoxic T cells that
recognize donor MHC class I and CD4+ helper T cells that orchestrate cytokine-driven inflammation and
recruit macrophages. Banff classification of acute rejection grades perivascular and peribronchiolar
mononuclear infiltrates. B cells (B) mediate antibody-mediated rejection, not cellular rejection. NK cells
(C) participate in ADCC but are not the primary effector in acute cellular rejection; eosinophils/mast cells
(D) are not central to allograft rejection.
Q6: In the context of antibody-mediated rejection (AMR), which of the following histologic
findings is most specific for AMR according to the Banff classification?
A. C4d deposition in peritubular capillaries with microvascular inflammation and circulating
donor-specific antibodies [CORRECT]
B. Interstitial edema with diffuse neutrophilic infiltrate
C. Tubulitis with CD3+ lymphocyte infiltration
D. Glomerular sclerosis and interstitial fibrosis with tubular atrophy
Correct Answer: A
Rationale: Per Banff criteria, AMR is diagnosed by the triad of: (1) histologic evidence of microvascular
inflammation (glomerulitis, peritubular capillaritis), (2) evidence of antibody-endothelium interaction
(C4d positivity in peritubular capillaries or moderate microvascular inflammation), and (3) serologic
evidence of donor-specific antibodies. C4d is the degradation product of C4b and serves as a footprint of
classical complement activation. Neutrophilic infiltrate (B) suggests pyelonephritis; tubulitis (C) is acute
cellular rejection; chronic changes (D) reflect chronic allograft injury.
Q7: A 50-year-old female receiving a hematopoietic stem cell transplant from an
HLA-identical sibling develops a maculopapular rash, diarrhea, and elevated liver enzymes
three weeks post-transplant. The immunologic mechanism of this graft-versus-host disease
(GVHD) involves:
A. Donor T cells recognizing recipient alloantigens on host tissues [CORRECT]
B. Recipient T cells attacking donor hematopoietic cells
C. Preformed recipient antibodies against donor HLA
D. Complement-mediated lysis of donor stem cells
Correct Answer: A
Rationale: GVHD occurs when donor immunocompetent T cells recognize recipient alloantigens
(especially minor histocompatibility antigens) on host tissues, leading to inflammation of skin,
gastrointestinal tract, and liver - the classic target organs. It is most common after hematopoietic stem cell
transplant but rarely reported after solid organ transplant (especially liver and intestine). Recipient attack
on donor cells (B) is rejection; antibody-mediated (C) and complement-mediated (D) mechanisms describe
hyperacute rejection, not GVHD.
, Q8: Which cytokine, primarily produced by activated CD4+ Th1 cells, is essential for the
proliferation and differentiation of cytotoxic T lymphocytes and is also the target of
calcineurin inhibitor therapy?
A. Interleukin-2 (IL-2) [CORRECT]
B. Interleukin-4 (IL-4)
C. Interleukin-10 (IL-10)
D. Transforming growth factor-beta (TGF-β)
Correct Answer: A
Rationale: IL-2 is the master growth factor for T cells, driving proliferation and differentiation of CTLs.
Calcineurin inhibitors (tacrolimus, cyclosporine) block IL-2 transcription by preventing NFAT nuclear
translocation, thereby suppressing T-cell activation - the cornerstone of maintenance
immunosuppression per AACE CCT standards. IL-4 (B) drives Th2 differentiation; IL-10 (C) is
immunosuppressive; TGF-β (D) promotes Tregs and fibrosis but is not the primary target of CNIs.
Q9: A transplant immunology laboratory reports a candidate's HLA typing as A*02:01,
A*24:02; B*07:02, B*35:01; DRB1*01:01, DRB1*03:01. In deceased-donor kidney allocation
under KAS, which loci are given primary weight for matching?
A. HLA-A, HLA-B, and HLA-DR (6-antigen match) [CORRECT]
B. HLA-C and HLA-DQ only
C. HLA-DP and HLA-DR
D. ABO blood group only
Correct Answer: A
Rationale: Under the original KAS framework, HLA-A, HLA-B, and HLA-DR (six antigens total) were the
primary loci used for allocation priority; a zero-mismatch (6-antigen match) kidney received highest
priority. The 2014 KAS revision maintained these loci for matching while introducing CPRA-based priority
and longevity matching (EPTS top 20% with top 50% ECD kidneys). HLA-C, DQ, and DP are not currently
used for allocation priority but are increasingly recognized for their role in DSA formation and AMR. ABO
compatibility is required but does not drive allocation priority except for pediatric priority.
Q10: Complement activation via the classical pathway in antibody-mediated rejection
culminates in the formation of which key effector complex that directly damages graft
endothelium?
A. Membrane attack complex (C5b-9) [CORRECT]
B. C3 convertase (C4b2a)
C. C1qrs complex
D. Properdin (factor P)
Correct Answer: A
Rationale: The classical complement pathway in AMR is activated when recipient IgG binds donor HLA on
endothelium, recruiting C1q, C4, and C2 to form the C3 convertase (C4b2a). Downstream, C5 is cleaved,
and C5b-9 (the membrane attack complex, MAC) is assembled, forming transmembrane pores that lyse
endothelial cells. C3 convertase (B) and C1qrs (C) are upstream intermediates; properdin (D) stabilizes the
alternative pathway C3 convertase.
