hla eplets in tranplantation€¦ · - solid-phase hla antibody testing is far from perfect....

HLA EPLETS IN TRANPLANTATION

ASHI 45th Annual Meeting – Technologist Forum

Massimo MangiolaPhD, D(ABHI)

OBJECTIVES – what will I touch on

HLA EPLETS LOADEplets mismatch concept applications

HLA ANTIBODY PATTERN RECOGNITIONHow to use what we know about eplets to guide us whenanalyzing SAB results

HLA EPLETS LOAD

A*02:01/A*02:01

NUMBERS OF HLA EPLETS EXPRESSED AT THE A-LOCUS

41 EPLETS

HLA EPLETS LOAD

HLA EPLETS MISMATCH

EPITOPES DIFFERENCE BETWEEN:A*02:01/A*02:01 DONOR & A*24:02/A*68:01 PATIENT

EPLETS EXPRESSED BY A*02:01/A*02:01 PATIENT = 41 EPLETS

EPLETS DIFFERENCE BETWEEN:A*02:01/A*02:01 DONOR & A*24:02/A*68:01 PATIENT

∆ = 8 EPLETS

HLA EPLETS MISMATCHEPLETS EXPRESSED BY A*02:01/A*02:01 PATIENT = 41 EPLETS

EPLETS DIFFERENCE BETWEEN

A*02:01/A*02:01 DONOR A*01:01/A*11:01 PATIENT


EPLETS DIFFERENCE BETWEEN

A*02:01/A*02:01 DONOR A*01:01/A*11:01 PATIENT

∆ = 24 EPLETS


HLA EPLETS MISMATCH

WHAT IS MATCHING IN THE EPLET ERA ?

Patient 1

DONOR

Patient 2

HLA ANTIGEN vs. EPITOPES/EPLETS MISMATCH

Patient 1

DONOR

Patient 2

Antigen MM = 2

Antigen MM = 2


Patient 1

DONOR

Patient 2

Antigen MM = 2

Antigen MM = 2

HLA Eplet MM = 24

HLA Eplet MM = 8


PARADIGM SHIFT:

PREVENTION

PARADIGM SHIFT:FROM INTERVENTION ….

PARADIGM SHIFT:FROM INTERVENTION … TO PREVENTION


NON-SELF, DONOR-DERIVEDHLA EPLETS


HIGH RISK(high epitope mismatch)

MODERATE RISK(moderate epitope mismatch)

LOW RISK(low epitope mismatch)

NO RISK (?)(NO epitope mismatch)


HIGH RISK(high epitope mismatch)

MODERATE RISK(moderate epitope mismatch)

LOW RISK(low epitope mismatch)

NO RISK (?)(NO epitope mismatch)

WHAT IS “RISK” INEPLET MISMATCHING ?

LET’S ASK THE LITERATURE


2787 KIDNEY TRANSPLANTS FROM 1995-2015


The current interest of the transplant community is to withdraw or minimize tacrolimus therapy to limit long-term serious adverse events.

However, early and late withdrawal strategies failed in two recent randomized, controlled trials (RCTs) largely due to rejection, dnDSA, or both shortly after tacrolimus cessation.

Given the failure of tacrolimus withdrawal trials, the community is now shifting to define minimal tacrolimus target trough levels.


HIGH ALLOIMMUNE RISK (DR or DQ EpMM >11)Keep tacrolimus trough level above 5.5 ng/mL

LOW ALLOIMMUNE RISK (DR or DQ EpMM <11)Tacrolimus withdrawal is possible !

HLA EPITOPES - Antibody Pattern Recognition


DISCLAIMERNOT THE SOLUTION TO THE ISSUE

THEORETICAL APPROACHTO BE USED ONLY TO KNOW IF MORE INVESTIGATION IS NEEDED

STRECTURAL/FUNCTIONAL EPITOPEImmunological synapse



CASE #0


A2, A68, A69

62GE

144TKH

A2, B57, B58


LUMINEX ANTIBODY UNICOR


TOOLS


http://www.epitopes.net/education.html


THESE TOOLS CANNOT BE USED ALONE TO DECIDE WHAT TO CALL BUT CAN BE USED TO PROMPT YOU TO LOOK INTO THE RESULTS

MORE CRITICALLY


CASE #1


<6000 MFI

6001-8000 MFI

>8001 MFI

DSA = B*27:05


EPLET 80N


EPLET 80N

B46 (5908 MFI)B65 (7475 MFI)B73 (7892 MFI)B78 (7961 MFI)Cw1 (4986 MFI)Cw8 (5645 MFI)Cw9 (3067 MFI)Cw10 (3286 MFI)C*12 (4870 MFI)C*14 (4560 MFI)C*16 (1954 MFI)


STRECTURAL vs. FUNCTIONAL EPITOPECan we talk independently about structural and functional ?


71ATD

76ET

77D

80T

80TL

80TLR

82LR

Eplet difference betweenB*27:05 and B*27:08



71ATD

76ET

77D

80T

80TL

80TLR

82LR



71ATD

76ET

80TLR



71ATD

76ET

80TLR

Only B*27:03/B*27:05



71ATD

76ET

80TLR

Only B*27:03/B*27:05

Missing A30, B37



71ATD

76ET

80TLR

Only B*27:03/B*27:05

Missing A30, B37

Missing B37



71ATD

76ET

80TLR

Only B*27:03/B*27:05

Missing A30, B37

Missing B37

Removing self-eplets andnegative beads eplets



71ATD

76ET

80TLR

Only B*27:03/B*27:05

Missing A30, B37

Missing B37

Removing self-eplets andnegative beads eplets

45EE 65QIA 66IC

69AA 71ATD 71KA

80TLR 97N 113H

163E


EPLET 80N

45EE 65QIA 66IC

69AA 71ATD 71KA

80TLR 97N 113H

163E

POSSIBLE FALSE


CASE #2


52 MFI

295 MFI

295 MFI

25 MFI

45 MFI

62 MFI


CASE #3


A*23:01, B44, B76, B45, B*82:01, B57, A2, B58, A69, A68, B49, B50

62GE


A*23:01, B44, B76, B45, B*82:01, B57, A2, B58, A69, A68, B49, B50

62GE

144TKH


A*23:01, B44, B76, B45, B*82:01, B57, A2, B58, A69, A68, B49, B50

163LS/G

62GE

144TKH


EXPOSED


151ARV 156L


... WHAT NOW ?


... WHAT NOW ?- CALL: A2, A68, A69, B44, B45, B57, B58, B76, B82 (cPRA = 70%)



- INVESTIGATE MORE: A23 (cPRA = 7%)



- INVESTIGATE MORE: A23 (cPRA = 7%)- MAY NOT BE ABLE TO DO MUCH FOR: B49, B50 (cPRA = 6%)



- INVESTIGATE MORE: A23 (cPRA = 7%)- MAY NOT BE ABLE TO DO MUCH FOR: B49, B50 (cPRA = 6%)

- SURROGTE FLOW: A23 (not for B49, B50)- MULTIANTIGEN BEADS: A23 (maybe not for B49,B50)- RISK STRATIFICATON


CASE #4

SUMMARY – common limitations


- Insufficient HLA genotyping resolution


- Insufficient HLA genotyping resolution∆ C*07:01P/C*07:02P and C*07:04P = eplet 156DA (explains B*44:02 +/B*44:03 -)



C7/C*07 HLA-C*07:XX⇢ ⇢

- Solid-phase HLA antibody testing is far from perfectdenatured/partially-denatured HLA antigensdisconnect between MFI and clinical correlation

- One test DOES NOT fits all scenariosThe misbelief around the relevance of antibody in transplant (kidney transplant) is totally our fault

- Eplet antibody testing - time to give up on the antigenEplet pattern recognition can help identifying false positive beadsEplet load may be relevant when crossing unacceptable

SUMMARY

- Antibody analysis in not a cut-off and click on print !

SUMMARY

SUMMARY

BUT SIMPLE, SOMETIMES IS JUST NOTHING !

hla eplets in tranplantation€¦ · - solid-phase hla antibody testing is far from perfect....

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