1. 2 Renal Unit, Belfast City Hospital, Belfast, BT9 7AB
Correlation of Luminex –Single Antigen Bead Assay and Renal function for post-transplant monitoring
Mahendra N Mishra 1, Tanya Shovlin 1, Ashley Meenagh 1, Aisling Courtney 2, Jeanie Martin 1
1 Northern Ireland Histocompatibility and Immunogenetics Lab, Blood Transfusion Service Building, Belfast City Hospital, BT9 7TS.
2 Renal Unit, Belfast City Hospital, Belfast, BT9 7AB
Introduction
BSHI / BTS guidelines recommend use of sensitive solid phase tests for detection characterization of both pre and post –transplant HLA Donor specific antibodies (DSA)
Post-transplant single antigen bead (SAB) assay results relevance depends on risk stratification and is used to monitor immunosuppression
Retrospective study: data of 25 non- consecutive renal allograft recipients analysed
SAB assay at least twice on pre & post transplant samples
HLA typing for recipient and donor by r-SSO /SSP
Individual DSA > 1000 was taken as positive
Temporal profile ,and MFI of DSA was correlated with creatinine levels
Patients and Methods
Aim and Objectives
Evaluate SAB assay for post –transplant DSA monitoring & correlate with serum creatinine
Study hierarchy of DSA leading to allograft dysfunction
Locus
Mismatched
Recipients
(antigens)
DSA
% showing DSA/ antigens A 22 32 11
34.4 B 20 28 10
35.7 C 16 5
22.7
DRB1 21 31 9 29
DRB345 17 26
34.6
DQB1 18 24 14 56
DPB1 4
15.3
Donor – recipient mismatches & DSA with MFI> 1000
Results Table 2:
Parameter
Value
Recipient age
Range years, (Mean = 38)
Female recipients
9 (36%)
Deceased organ recipients
10 (40%)
Retransplants
HLA incompatible transplants
4 (16%)
Demographic profile of 25 patients
Results Table 1:
Relationship of DSA with renal function
HLA DSA in normal and compromised renal function
Chart depicting peak DSA and mean creatinine
for seven recipients with normal renal function
SAB assay is used for post-transplant monitoring
Anti–HLA DQB1 was most frequent and anti-DP least common with anti-HLA C intermediate value probably due to lower expression
Recurrence of original disease seen in two cases with no DSA
Reactivity against all 7 loci observed in patients with DSA, but normal renal function.
Discussion
Patients are non consecutive and all DSA is not de-novo
Small sample size
Post–Transplant DSA is done selectively, often for those with impending graft dysfunction
Limitations
Elevated DSA may not be concordant with rise in serum creatinine
Existing methods were inadequate for discerning between pathogenic & innocuous antibodies
Discussion
HLA–DQB1 DSA were most common
Both DSA levels and renal function have to be considered for treatment monitoring
Clinical significance of individual & additive DSA values have to be correlated with allograft function
Conclusions
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