1

Guidelines for the Detection and Treatment of

Donors-specific anti-HLA Antibodies (DSA) in

Haploidentical Hematopoietic

Cell Transplantation

Marcelo A. Fernández Viña, Ph.D.

Department of Pathology

Medical School

Stanford University

2

Current protocols utilizing Haplo-

identical Donors

• Post-transplantation cyclophosphamide

(PTCy)

• Selective alpha-beta T-cell depletion

• Enhanced GVHD prevention with multiple

agents:

– ATG in non-T-cell-depleted

– extracorporeal photo-depletion and T-

regulatory cells (Tregs) in T-cell-depleted

3

Goals of Allogeneic BMT

Achieve Engraftment by Reducing Risk of

Primary Graft Failure (PGF):

• Patient’s immune system may cause

rejection

• Donor’s immune system may enhance the

engraftment through the destruction of

patient’s immune cells that cause rejection

• T-cells, B-cells, NK cells

Impact of High Resolution Mismatches (Allele Level) & Broad

Mismatches (Serologically Detectable) in Alleles of HLA Loci

Flomenberg et al Blood , 2004

6

Differences in the number of Mismatched Epitopes when the Patient is

Homozygous or Heterozygous at the Mismatched locus

0

1000

2000

3000

4000

5000

6000

7000

A*

23

:01

A*

80

:01

A*

01

:01

A*

24

:02

A*

36

:01

A*

29

:02

A*

24

:03

A*

66

:02

A*

33

:01

A*

33

:03

A*

29

:01

A*

34

:01

A*

32

:01

A*

11

:02

A*

43

:01

A*

11

:01

A*

03

:01

A*

74

:01

A*

26

:01

A*

34

:02

A*

69

:01

A*

68

:02

A*

25

:01

A*

02

:06

A*

66

:01

A*

02

:01

A*

68

:01

A*

02

:03

A*

30

:01

A*

30

:02

A*

31

:01

IgG

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Self HLA-A

Antibody

Tests by

Assays

Humoral Allo-sensitization in Hematopoietic

Stem Cell Transplantation

Anasetti C, et al. N Engl J Med. 1989;320:197-204

Ottinger HD, et al. Transplantation. 2002;73:1280

Effect of HLA compatibility on engraftment of bone

marrow transplants in patientswith leukemia or

lymphoma.

N Engl J Med. 1989 Jan 26;320(4):197-204.

Anasetti C, Amos D, Beatty PG, Appelbaum FR,

Bensinger W, Buckner CD, Clift R, Doney K,

Martin PJ, Mickelson E, et al.

In a multivariate binary logistic regression analysis, independent risk factors associated with graft failure were:

Donor incompatibility for HLA-B and D (relative risk = 2.1; 95 percent confidence interval, 1.7 to 2.5; P = 0.0004)

A positive crossmatch for anti-donor lymphocytotoxic antibody (relative risk = 2.3; 95 percent confidence interval, 1.8 to 2.8; P = 0.0038)

SERUM

Scoring

Under a Microscope

CDC ASSAY

Cell Death

(%)

0~10 1

11~20 2

21~50 4

51~80 6

81~100 8

ScoreDNA Dye

Lymphocyte

Rabbit/Autologous C’

CFAb

Non-CFAb

Anti-hIgG

HLA

HLA

Dead Lymphocyte

0

100

200

300

400

500

600

MCS

NegativeFlow Crossmatch

PositveFlow Crossmatch

Negative CDCPositive CDC

Comparison between Flow Cytometric (FXM) and

Complement Dependent Cytotoxicity (CDC) Cross-Matches

Luminex-IgG

SERUM

HLA-Ag Coated

Luminex Beads

Autologous C1q

CFAb

Non-CFAb

Anti-hIgG

0

1000

2000

3000

4000

5000

6000

7000

A*

23

:01

A*

80

:01

A*

01

:01

A*

24

:02

A*

36

:01

A*

29

:02

A*

24

:03

A*

66

:02

A*

33

:01

A*

33

:03

A*

29

:01

A*

34

:01

A*

32

:01

A*

11

:02

A*

43

:01

A*

11

:01

A*

03

:01

A*

74

:01

A*

26

:01

A*

34

:02

A*

69

:01

A*

68

:02

A*

25

:01

A*

02

:06

A*

66

:01

A*

02

:01

A*

68

:01

A*

02

:03

A*

30

:01

A*

30

:02

A*

31

:01

IgG

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Self HLA-A

Antibody

Tests by

Assays

14

Evaluation of DSA by a Solid Phase Assay

with Single Antigen Beads

DSA definition: Analysis of Donor’s Mismatched

Antigens and HLA antibody profile determined by the

Solid Phase Assay (SA)

Virtual cross-match

Excellent surrogate of FXM assay

Does not require viable donor cells

Test has less interferences (Rituximab, ATG,

Alemtuzumab)

DSA against various donors can be evaluated at

different time periods

C1q assay: May identify high risk DSA; useful for

monitoring DSA in patients receving IvIg

16

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

14000

15000

16000

17000

18000

19000

20000

21000

22000

23000

24000

25000

0 100 200 300 400 500

Dominant DSAFlow Crossmatch Cut Off

Negative Flow XM Positive Flow XM

Negative CDC Crossmatch

Positive CDC Crossmatch

MCS Flow Crossmatch

DSAMFI

HLA-Ag Coated

Luminex Beads

Luminex-C1q

SERUM

hC1q

CFAb

Non-CFAb

Anti-hC1q

G. Chen

0

5000

10000

15000

20000

25000A

*2

3:0

1A

*8

0:0

1A

*0

1:0

1A

*2

4:0

2A

*3

6:0

1A

*2

9:0

2A

*2

4:0

3A

*6

6:0

2A

*3

3:0

1A

*3

3:0

3A

*2

9:0

1A

*3

4:0

1A

*3

2:0

1A

*1

1:0

2A

*4

3:0

1A

*1

1:0

1A

*0

3:0

1A

*7

4:0

1A

*2

6:0

1A

*3

4:0

2A

*6

9:0

1A

*6

8:0

2A

*2

5:0

1A

*0

2:0

6A

*6

6:0

1A

*0

2:0

1A

*6

8:0

1A

*0

2:0

3A

*3

0:0

1A

*3

0:0

2A

*3

1:0

1

IgG C1Q

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Self HLA-A

A*02, A*24, A*25, A*26,A*34, A*68, A*69, A*43

may be acceptable by the C1q Assay

Antibody

Tests by

Assays

Testing for Donor Specific

Antibodies in Transplants with a

Haplo-identical donor

T-cell depleted (2005)

Post-Transplant Cyclophosphamide

(2010)

DSA in TCD Haploidentical Stem Cell Transplantation

Ciurea SO, de Lima M, Cano P, Korbling M, Giralt S, Shpall EJ, Wang

X, Thall PF, Champlin RE, Fernandez-Vina M

DSA were detected in 5 of 24 consecutive patients (21%)

4/24 patients had primary graft failure (PGF)

3/4 (75%) patients with DSA failed to engraft as compared

with 1/20 (5%) without DSA (p=0.008, RR=57.0)

DSA\Engraftment YES NO

YES 1 3

NO 19 1

“High risk of graft failure in patients with anti-HLA antibodies undergoing

haploidentical stem-cell transplantation”

Transplantation. 2009 Oct 27;88(8):1019-24

Graft Failure #2; haplo-transplant with anti-class

I antibodies; reduction by pre transplant

plasmapheresis

Haplotype A B Cw DRB1 DRB3 DRB4 DRB5 DQB1 DPB1

Patient a 010101g 530101 04KBG 0701 010101 0202 020102

Patient c 290201 510101 160101 080401 030101 0301

Donor a 010101g 530101 04KBG 0701 010101 0202 020102

Donor d 0211 391301 070201 0404 0103 030201 0402

FI Initial 8597 7431 3254 801

FI Pre TX 1938 3163 NT 681

FI Post TX 17 212 NT 281

FI Post TX 2005 3948 NT 714

DSA and PGF in TCD HaploSCT___________________________________________________________

DSA: + weak; + + intermediate; + + + strong; + + + + very strong; AB – antibody

________________________________________________________________________________________

Ciurea SO, et al. Transplantation. 2009;88:1019.

DSA detected in 5 of 24 TCD Haplo SCT patients (21%)3/4 (75%) patients with DSA had PGF vs. 1/20 (5%) without DSA (p=0.008)

Testing for Donor Specific

Antibodies - MUD

CIBMTR (case control)

MDACC (692 consecutive TX, no

selection)

Anti-HLA Antibodies and Virtual Cross

Match in MUDs

Retrospective study - DSA found in 9/37 MUDT patients with

graft failure

1/78 had DSA in the matched control group of patients who

engrafted (TCR grafts, 85% mismatched at DP locus)

Spellman S, Bray R, Rosen-Bronson S, Haagenson M, Klein J, Flesch S, Vierra-Green C, Anasetti C.

The detection of donor-directed, HLA-specific alloantibodies in recipients of unrelated hematopoietic cell transplantation is predictive of graft failure.

Blood. 2010 Apr 1;115(13):2704-8

PGF Control

DSA 9/37 (24%) 1/78 (1%)

Class I +/- Anti-DP 5 1

Anti-DP alone 4 0

DSA and PGF

RR = 24.8 – 28.1

Ciurea SO, Thall PF, Wang X, Wang SA, Hu Y, Cano P, Aung F, Rondon G,

Molldrem JJ, Korbling M, Shpall EJ, de Lima M, Champlin RE, Fernandez-Vina M.

Donor-specific anti-HLA Abs and graft failure in matched unrelated donor

hematopoietic stem cell transplantation.

Blood. 2011 Nov 24;118(22):5957-64

592 MUD TX

75 % of the 8/8 transplants present at least one

mismatch in DP, DQ, DRB3/4/5 in the HvG vector

20 % of HSC patients are immunized against HLA

HLA Immunization in FEMALE HSCT patients: 30%

HLA Immunization in MALE HSCT patients: 10%

3.3 % present antibodies against HLA-DP (1/2 MUD TX have one or two DP mismatches and DSA anti HLA-DP)

Univariate Logistic Regression Model for Graft Failure in MUDT

Variable

Parameter

Estimate

Parameter

Standard Error

Univariate

P-value Odds Ratio

Male (vs. female) -0.53 0.47 0.26 0.59

Black (vs. white) 1.17 0.78 0.14 3.22

Others (vs. white) -12.15 316.51 0.97 0.00

AHA= yes (vs. no) 0.91 0.49 0.06 2.48

DSA = yes (vs. no) 3.06 0.77 0.0001 21.33

HEL HvG = 8 (vs. 7) -0.31 0.64 0.62 0.73

LEL HvG = 6 (vs. <6) -0.53 0.64 0.41 0.59

CD34 cell numbers

infused

-0.51 0.38 0.18 0.60

CMV mismatch = yes (vs.

no)

0.27 0.47 0.56 1.31

Sex mismatch = yes (vs.

no)

0.60 0.47 0.21 1.82

ABO mismatch = yes (vs.

no)

1.35 0.63 0.03 3.86

AHA – anti HLA antibodies; DSA – donor-specific AHA; HEL – high expression loci; LEL – low expression loci;

HvG – host versus graft direction

MVA: DSA (p=0.0001) and ABO mm (p=0.04) remained significantly associated with GF

Other Associations: Gender, Number of Pregnancies

and anti-HLA antibodies

Variable N

Coefficien

t SE P-value OR 95% CI

Intercept -2.71 0.60 <0.0001 - -

Male vs. Females 0

pregnancies

356 0.73 0.62 0.24 2.1 0.62 - 6.94

Female: Number of

pregnancies = 1 (vs.

0)

37 1.85 0.70 0.008 6.3 1.62 -

24.85

Female: Number of

pregnancies ≥ 2 (vs.

0)

152 2.25 0.62 0.0003 9.5 2.83 -

32.02

Significant association between gender and the presence of

AHA: 30.8% females vs 12.1% males had anti-HLA

antibodies (p<0.0001)

7/8 pts with DSA were females

Haplo-HSCT PTCy:

Ciurea et al.• 122 consecutively treated haploidentical stem cell

transplants

• DSA: 18%

• PGF: 32% of patients DSA vs only 4% without

DSA (P <0.001)

• Time to engraftment: 19 days vs. 18 days

(P=0.004)

• Yoshihara et al, Chang et al, similar findings

• DSA in haplo-setting: 10-21 %

• Mother/child. Preganacy and Transfusion

30

Sources of Immunization

against HLA (sensitization) Pregnancies

Transfusions

Transplants

Grafts (homografts - veins)

Same epitope present in alleles of the same or

different loci with different levels of expression

Cumulative Incidence of PGF by MFI levels and C1q Positivity at Transplant (Ciurea et al)

______________________________________________________________

C1q-Positive DSA. Is there a DSA cut-

off more detrimental toengraftment?

Most patients who had positive C1q DSA in the

MDACC study had higher median MFI of

DSAslevels (all more than 5,000 MFI) compared

with those whohad negative C1q

DSA was considered postive by IgG test for

MFI>1,000

PGF increases with MFI levels above 5,000

The rejection rate for patients with DSA < 5,000

MFI was 9 % vs. 54% for patients with DSA

>5,000 MFI

Decreased Survival after PGF

34

Interferences: DSA with Low MFI and FXM

High MCSSo called ‘pro-zone effect’: serum tested in dilution results in higher MFI for the same antigen

This is not a true-pro-zone effect but is the result of inhibitors or competitors for the target antigen

Complement factors may block access to the detection reagent (anti-IgG)

Other antibody isotypes: IgM directed against the same epitope-molecule

Pretreatment of the serum (heat inactivation) or addition of EDTA minimize the interferences and result in more reproducible tests

EDTA implementation is easier

0

5000

10000

15000

20000

25000

Neat 1:2 1:4 1:8 1:16 1:32

SERUM DILUTION EFFECT ON LMX-C1q

Peds Heart Serum 3/22/11

Dilution: AB serum was used as diluent .

#40=DQA1*0201, DQB1*03:01

#39=DQA1*0301, DQB1*03:01

#67=DQA1*0505, DQB1*03:01

#41=DQA1*0601, DQB1*03:01

#66=DQA1*0503, DQB1*03:01

DRB1_1 DRB1_2 DQA1_1 DQA1_2 DQB1_1 DQB1_2

Patient 03:01 13:02 01:02 06:02 06:04

Donor 01:01 11:01 01:01 05:05 05:01 03:01

Inhibitory Factor; DQB1.E45

DQA1*04/05/06-DQB1*E45

Antibodies against epitopes present in multiple

Antigens of the SA-Bead Mixture may appear as

weakly reactive

Multiple antigens present in different beads compete for the same amount of antibodies in a single tube

MFI may be low and if FXM cross match is done the MCS are higher than expected

Pattern of reactivity to be analyzed on the basis of possible epitopes

Expert interpretation

Epitope analysis can be useful for virtual cross-match HLA alleles not represented in the panel

DPB1 alleles included in the Single Antigen Panel –

Dimorphisms at residue 56 and residues 85-87 may

define two bi-allelic serologic systems

HLA-DP Single Antigen reactions of two

patient’s sera show two mutually exclusive

patterns

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0

1000

2000

3000

4000

5000

6000

7000L

04

01

A

56

8

5G

PM

87

01

01

A

56

8

5E

AV

87

05

01

A

56

8

5E

AV

87

11

01

A

56

8

5E

AV

87

19

01

A

56

8

5E

AV

87

13

01

A

56

8

5E

AV

87

09

01

E

56

8

5E

AV

87

10

01

E

56

8

5E

AV

87

14

01

E

56

8

5E

AV

87

17

01

E

56

8

5E

AV

87

03

01

E

56

8

5E

AV

87

L 0

201

E

56

8

5G

PM

87

L 0

402

E

56

8

5G

PM

87

VH

DR

B1

*11

01

58

E

0401, 0401

0201, 0301

Immunogenic Serologic D-PEpitopes E-56 and A56

EAV-85-87 and GPM-85-87

DPA1*01:03 and DPA1*02:01 /02:02 (DPA1*03and

DPA1*04 alleles fall withing these groups, respectively)

Other Epitopes (less immunogenic)

DED-55-57 and DEE 55-57

ILEEE (D)-65-71 (shared with DRB1)

Other private epitopes

Limitations of the Solid

Phase Assay Does not detect expression variants

Some DSA with high MFI may not result in

positive cross-matches

DSA for alleles of LEL

Same epitope present in alleles of the same or

different loci with different levels of expression

New Slide 42

DRA-DRB1 DRA-DRB3/4/5

DQA1-DQB1DPA1-DPB1

HLA-Class II Molecules Encoded byDifferent Loci are Expressed in Different

Amounts on the Cell Surface(High Expression and Low Expression)

43

Petersdorf EW et al. N Engl J Med 2015;373:599-609.

Correlation of HLA-DPB1 Expression with the rs9277534 Allele in the 3′ Untranslated Region of HLA-DPB1.

Variable Epitope Expression

Interlocus Epitopes:

B46+B73+C1 KIR ligand group (residues 76, 77, 80)

DRB1*11-DPB1 ‘E’-56

DRB1-DRB3 (A- -V at residues 57-60)

Patient carrying DRB3*0202 makes an antibody

reactive with DRB3*0101 (sequence motif

shared by reactive DRB1 and DRB3 alleles)

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0

1000

2000

3000

4000

5000

6000

7000D

RB

1*0

90

1

DR

B3

*01

01

DR

B1

*07

01

DR

B1

*12

02

DR

B1

*12

01

DR

B1

*14

01

DR

B3

*02

02

Patient'sgenotype:DRB1*1101-DRB3*0202DRB1*1501-DRB5*0101

The alleles DRB1*0701, 0901 and DRB3*0101 and DRB3*0301 share a

sequence motif that may correlate with a serologic epitope

51 60

DRB1*010101 TELGRPDAEY

DRB1*030101 ----------

DRB1*040101 ----------

DRB1*070101 ------V--S

DRB1*080101 ------S---

DRB1*090102 ------V--S

DRB1*0902 ----------

DRB1*100101 ----------

DRB1*110101 -------E--

DRB1*120101 ------V--S

DRB1*120201 ------V--S

DRB1*130101 ----------

DRB1*140101 ------A--H

DRB1*150101 ----------

DRB3*01010201 ------V--S

DRB3*020201 R---------

DRB3*030101 ------V--S

DRB4*010101 ----------

DRB5*010101 ----------

Bead ID

DRB1 DRB1 DRB3/4/5 DRB3/4/5 NFI

52 DRB1*0701 DRB1*1501 DRB4*0103 DRB5*0101 6546

58 DRB1*0901 DRB1*1502 DRB4*0101 DRB5*0108N 6430

67 DRB1*1301 DRB1*1454 DRB3*0101 DRB3*0202 6016

54 DRB1*0302 DRB1*0701 DRB3*0101 DRB4*0101 5813

50 DRB1*0901 DRB1*1001 DRB4*0103 - 5408

92 DRB1*0301 DRB1*0701 DRB3*0202 DRB4*0101 5373

57 DRB1*0901 DRB1*1202 DRB3*0202 DRB4*0103 5169

66 DRB1*0302 DRB1*1303 DRB3*0101 - 4720

49 DRB1*0404 DRB1*0901 DRB4*0101 DRB4*0103 4705

53 DRB1*0301 DRB1*0701 DRB3*0202 DRB4*0101 4320

55 DRB1*0802 DRB1*1201 - DRB3*0101 4001

59 DRB1*1101 DRB1*1202 DRB3*0202 DRB3*0301 3880

62 DRB1*0302 DRB1*1201 DRB3*0101 DRB3*0202 3865

93 DRB1*0301 DRB1*0901 DRB3*0101 DRB4*0103 3769

45 DRB1*0404 DRB1*1202 DRB4*0103 DRB3*0301 2976

40 DRB1*0101 DRB1*0701 DRB4*0101 DRB5*0101 2774

68 DRB1*1402 DRB1*1602 DRB3*0101 DRB5*0202 2509

63 DRB1*1302 DRB1*1501 DRB3*0301 DRB5*0101 1952

51 DRB1*0701 DRB1*1202 DRB4*0103N DRB3*0301 1625

64 DRB1*0301 DRB1*1302 DRB3*0202 DRB3*0301 1434

60 DRB1*1102 DRB1*1454 DRB3*0202 - 1349

46 DRB1*0405 DRB1*1402 DRB4*0103 DRB3*0101 1337

56 DRB1*0801 DRB1*1401 - DRB3*0201 1289

47 DRB1*0401 DRB1*1602 DRB4*0103 DRB5*0101 631

48 DRB1*0404 DRB1*0801 DRB4*0103 - 33

37 DRB1*0101 DRB1*1301 - DRB3*0202 0

38 DRB1*0101 DRB1*1601 - - 0

39 DRB1*0101 DRB1*0401 - DRB4*0103N 0

41 DRB1*0101 DRB1*0801 - - 0

42 DRB1*0103 DRB1*1501 - DRB5*0101 0

43 DRB1*0103 DRB1*0301 - DRB3*0202 0

44 DRB1*0404 DRB1*1101 DRB4*0103N DRB3*0202 0

61 DRB1*1101 DRB1*1501 DRB3*0202 DRB5*0101 0

65 DRB1*0301 DRB1*1303 DRB3*0101 DRB3*0202 0

94 DRB1*0302 DRB1*1001 DRB3*0202 - 0

PHENOTYPE

Panel Reactivity of a serum recognizing DRB alleles carrying

57-V60S and DRB1*1401/1454 – Effect of double Expression

of weak Antibodies and or low Density Target Antigens

Variable Epitope Expression

Cell types

50

Lower Expression of HLA in CBU-

CD34

Bone

Marrow

CD34

Cord Blood

CD34

HLA antibody screening collection and testing.

Donor selection

1. Perform HLA antibody screening prospectively for all patients

receiving a transplant from any donor that may not be HLA identical

to the patient by descent (i.e., any non-sibling donor)

2. Collect initial serum specimen before initiation of search for

unrelated donor, haplo-identical donor or cord blood

3. Collect and test a second serum specimen 14 or more days after any

immunizing event (also allograft removal)

4. Collect and test an additional serum specimen six months after the

sample collected for initial antibody testing or after the last

immunizing event

5. Collect and test a serum specimen 30 days pre-transplant (some

CIBMTR protocol)

6. Select antibody compatible donors; consider desensitization if no

other suitable donor is identified

Desensitization

i. Antibody removal by using plasmapheresis or

immunoabsorption

ii. Inhibition of antibody production by using monoclonal

antibodies to CD20+ B lymphocytes (rituximab),

proteasome inhibitor against alloantibody producing plasma

cells (bortezomib) or anti-CD38 (DARZALEX or

Daratumumab)

iii. Antibody neutralization using intra-venous immunoglobulin

(IVIg)

iv. Absortion of DSA with donor HLA antigens (platelet

transfusions or white blood cell infusion in the form of an

irradiated “buffy coat”)

v. Inhibition of the complement cascade by anti-C5

monoclonal antibody (Eculizumab)

Desensitization approach for patients with DSAs

undergoing haploidentical stem

cell transplantation (MD Anderson CC)

55

JHU Protocol• Extrapolated experience for desensitization in solid organ

transplantation

• Combination of repeatedplasmapheresis, IVIg and

immunosuppressive medications

• Aalternate-day, single volume plasmapheresis followed by IVIg

(100 mg/kg), tacrolimus (1 mg, i.v.per day) and mycophenolate

mofetil (1 g two times daily)

• Starts 1–2 weeks before the beginning of transplant

conditioning, depending on each patient’s starting DSA levels

• DSA levels monitored throughout desensitization; and on day

−1 to determine if there was any DSA rebound that would

require additional treatment. For patients experiencing an

increase or rebound of DSA on days −1, 1, and 2, additional

plasmapheresis depending on extent of DSA56

Recommendations (1)• DSA and C1q levels should be monitored before

and after treatment, as well as after transplant

• Recommended: testing DSA (and C1q if DSA

present) at least within 1 month prior to admission

• All patients with DSA MFI 1,000–2,000 should

receive treatment

• Repeat DSA testing after treatment/before

infusion of stem cells and after transplant

• Recommended: weekly DSA monitoring

thereafter until clearance, as DSA levels will not

clear immediately after treatment and/or stem cell

infusion 57

Recommendations (2)1) DSA testing (by Luminex platform and/or cell-based

assays) be performed in all candidate patients for

haploidentical (or HLA mismatched) donor transplants

2) If DSA > 1,000 MFI, C1q testing and/or cell-based assays

must be done to further assess the risk to the allograft

3) DSA testing should be incorporated in donor selection

prior to transplantation; if DSA > 1,000 MFI in the

absence of an alternative suitable donor, it is

recommended that patients undergo desensitization

therapy, especially with high DSA levels (>5,000 MFI)

and/or C1q positive, which pose a very high risk to the

allograft;

4) The choice of desensitization protocol should be based on

prior local experiences58

Histocompatibility Factors

Affecting Engraftment

• HLA-mismatches in the Host versus graft

direction (HvG mismatch)

• Serologic level HLA-class I mismatches

• Patient’s Homozygosity (HvG mismatch)

• Donor-specific anti-HLA Antibodies

• ABO Major Mismatch

PGF: General Considerations Graft source, graft manipulation, conditioning and

immunosuppression. Cell dose

Differences: Variations: in end points

level of expression of target antigen

test cut-off values to define DSA

DSA cut-offs: MFI> 2,500

MFI>5,000

IgG+C1q positive

16-50 % PGF have DSA

T-cell immunity

Conditioning, Immunosuppressive regimens (ATG, post TX Cyclophosphamide)

Preservation of patient’s Immune System (Primary Disease and Stage)

Graft Manipulation

Acknowledgements____________________________________________________

Stefan Ciurea

Kai Cao

Pedro Cano

Richard Champlin

David Miklos

Ge Chen

Dolly Tyan