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

Patient 2

HLA ANTIGEN vs. EPITOPES/EPLETS MISMATCH

Patient 1

Patient 2

Antigen MM = 2

Patient 1

Patient 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

144TKH

A2, B57, B58

LUMINEX ANTIBODY UNICOR

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

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 ?

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

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

Missing A30, B37

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

Missing A30, B37

Missing B37

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

Missing A30, B37

Missing B37

Removing self-eplets andnegative beads eplets

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

EPLET 80N

45EE 65QIA 66IC

69AA 71ATD 71KA

80TLR 97N 113H

POSSIBLE FALSE

CASE #2

52 MFI

295 MFI

25 MFI

45 MFI

62 MFI

CASE #3