Clinical Differences

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Clinical Differences Between Anti-HLA and
Anti-ABO Antibodies In Renal Transplantation T
he 7th Banff Conference on Allograft
Pathology Millie Samaniego, MD Johns Hopkins
School of Medicine
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Controversies In Transplant Immunology

• Humoral theory of graft rejection
• Cellular theory of graft rejection

Sir Peter Medawar (1915-1987)
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MH Sayeh and LA Turka. N Engl J Med 1998
338(25)1813-21
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REMAINING BARRIERS TO RENAL TRANSPLANTATION
Nearly 30 of the 52,000 patients on the kidney
waiting list are sensitized due to previous
transplant, blood transfusion, or pregnancy.
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MHC MOLECULES
?1-chain
?2-chain
?2m
?3-chain
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REMAINING BARRIERS TO RENAL TRANSPLANTATION

• There is a 35 chance that any 2 individuals will
  be ABO incompatible
• 1/3 of potential live donors are excluded
  immediately due to ABO incompatibility.

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ABO GROUP ANTIGENS
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Source OPTN/SRTR DATA as of August 1, 2001
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LAG BETWEEN CLINICAL AND BENCH RESEARCH

• Characterization of the humoral response to
  transplantation antigens
• Targets of antibody response
• HLA versus Non-HLA antigens (ABO, polymorphic
  tissue antigens, endothelial cell antigens)
• Animal models
• Which is/are the effector (s) of injury Antibody
  or the Complement System?
• Poor understanding of the role of the B-cell in
  rejection
• APC, Effector, co-stimulator?

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Immunomodulation and Accommodation in Kidneys
Transplanted Across Donor Specific HLA
Antibodies and ABO Incompatibility

• MD Samaniego, AA Zachary, KE King,
• L Racusen, M Haas, RA Montgomery 
• Johns Hopkins University

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INCLUSION CRITERIA AND END-POINTS

• PRE-EMPTIVE PROTOCOL
• Positive Donor specific X-match before Tx.
• Identification of donor-specific anti-HLA Ab
  pre-Tx.
• End-point Negative Donor specific X-match before
  Tx.
• RESCUE PROTOCOL
• Histologic and immunofluorescent features of
  humoral rejection.
• Identification of donor-specific anti-HLA Ab
  post-Tx.
• End-point Biopsy-proven resolution of rejection
• Elimination of donor-specific anti-HLA Ab

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PP/CMV-IVIg Protocol

• Plasmapheresis
• Delivered via COBE Spectra cell separator.
• Removal of 1 plasma volume, replaced with albumin
  or FFP.
• Given QOD until endpoint
• Pre-emptive group Neg cytotoxic donor-specific
  X-match
• Rescue Elimination of DSA

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PP/CMV-IVIg Protocol

• CMV Hyperimmune globulin
• Infusion followed each plasmapheresis
• Each patient received 100 mg/kg/dose

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PP/CMV-IVIg Protocol
Immunosuppression

• Pre-Emptive Group
• At 1st PP/CMV-IVIg session
• FK506 trough 10-15 ng/ml
• MMF 2g/d
• At time of Transplant
• Daclizumab x 5 doses
• Methylprednisolone pulse (500 mg/d x 3 days)
• Steroid taper

• Rescue Group
• Methylprednisolone pulse
• (500 mg/d x 3 days)
• Steroid taper
• FK506 trough 10-15 ng/ml
• MMF 2g/d

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CLINICAL OUTCOMES PRE-EMPTIVE PP/CMV-Ig THERAPY
FOR A POSITIVE CROSSMATCH
6 graft losses 1 noncompliance 1 pt death due
to sepsis 1 pt death due to biopsy
complication 1 recurrent disease 2 AMRx
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CLINICAL OUTCOMESAMRx RESCUE USING PP/CMV-Ig
8 graft losses 2 recurrent Dz, 2 chronic
rejection, 2 death with normal renal Fx, 1
surgical complication, 1 with recalcitrant AMRx
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Risk Factors
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Impact on HLA-Specific Antibodies

• Of the 49 patients
• 3 graft losses 2 to rejection, 1 to
  Bx-related incident
• 1 patient died with functioning graft, 3 years
  post-Tx
• 1 year graft survival 91

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ELISA vs C4d Staining
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CONCLUSIONS-1

• Anti-HLA Antibodies
• Donor specific unresponsiveness
• Anti-HLA DSA remains undetectable in all patients
  treated pre-emptively with PP/IVIG for a ()
  Xmatch and in 28 of 33 patients in the rescue
  protocol
• 3rd party anti-HLA Ab often returns

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ABOI-TRANSPLANT PROTOCOL
End-point Isoagglutinin titer ? 116 by AHG

• Plasmapheresis
• CMV-IVIg 100 mg/Kg after plasmapheresis
• Pre-Tx splenectomy
• Immunosuppression
• Daclizumab x 5 doses
• Methylprednisolone pulse (500 mg/d x 3 days)
• Steroid taper
• FK506 trough 10-15 ng/ml
• MMF 2g/d

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Characteristics of ABOI Kidney Transplant
Recipients
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ABO Incompatible Transplants With Rituximab in
lieu of Splenectomy
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Blood Group Antigen Expression on ABOI
Transplanted Kidneys
Pre-Tx
Post-Tx
1 Week
1 Month
HE
Anti-A1
No decrease in blood group antigen staining has
been observed in any sections examined thus far,
suggesting that decreased antigen expression on
the donor kidney does not explain accommodation.
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CONCLUSIONS-2

• ABO Isoagglutinins Accommodation
• Isoagglutinin titers rebound after cessation of
  PP/IVIG but this does not appear to have
  consequences for the graft
• C4d staining is not indicative of rejection
  unless other features are present

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SPEAKER OBJECTIVES

• To recognize that antibody responses to HLA and
  ABO molecules are qualitatively different
• To recognize that early graft acceptance in
  patients with preformed HLA usually requires
  elimination of DSA
• To recognize that in ABOI transplants low levels
  on ABO isoagglutinins may facilitate engraftment
• A regimen of plasmapheresis, IVIg and anti-B
  cells monoclonal antibodies enables renal
  transplantation across a DSA or ABO
  incompatibility barrier

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ACKNOWLEDGEMENTS

• INKT PROGRAM
• Bob Montgomery
• Andrea Zachary
• Matt Cooper
• Karen King
• Renal Pathology
• Lorraine Racusen
• Mark Haas

• Baldwin Laboratory
• Wink Baldwin
• Barbara Wasowska
• RIST Investigators
• Yolanda Becker
• Nina Tolkoff-Rubin
• Mark Pescovitz
• Gonzalo Gonzalez-Stawinski