Background In this paper the use of proficiency testing samples for establishing a standalone Histocompatibility &Immunogenetics laboratory in India is discussed. Aims and objectives The aim of presenting this work is to discuss in a wider forum the adequacy of methods and results of testing EQAS samples for HLA typing, antibody screening and specification in limited resources setting.
Methods Samples of UK NEQAS Scheme 6/2014, Scheme 3/2014 and from an ISO15189:2012 accredited laboratory (n = 10 each), were used for validation of pooled bead assay. Phenotype and single antigen bead assay were validated with Scheme 3/2014 samples. Samples of Scheme 4A2 (n =3), ED 3/22 (n =2) and ten samples from another ISO15189:2012 accredited laboratory were used for validation of HLA typing by Luminex (r-SSO). Tests were performed on Luminex 200 using kits procured from Immucor (India) according to the product insert. Flowcytometry crossmatch was done on Beckman Navios EX (BA19028) Flowcytometer. Ten known samples were tested for validation of HLA typing by Sequence specific primers (SSP). Controls were included in each assay.
Results DNA typing was accurate to the second field for HLA-ABCDRDQB1 alleles for all samples except for two HLA -C alleles and one DQA1 of educational scheme. Remaining results were concordant in first field. Other than six samples of Scheme 6 /2014 (Table), 30 test results were matched. Phenotype assay on these six samples showed concordance with our lab results which can probably be explained by loss of reactivity due to storage or during transportation. Scheme 3 results were > 90% concordant. Flow crossmatch results showed initially 50% concordance, but after trouble shooting were 100% concordant. Conclusions HLA typing in first field, Flowcytometry crossmatch and antibody specification results were satisfactory. EDTA pre-treatment will be introduced for antibody testing and future external proficiency testing shall be closely monitored.
Table showing Discordant Results
|
ID |
Pathkind |
Consensus |
Discordance |
Phenotype assay For discordant results |
HLA |
Typing |
|
613 |
N N |
P N |
FN Cl I |
Negative |
(PK) |
Consensus |
|
616 |
N N |
P P |
FN Cl I &II |
Negative I &II |
C*07:03 |
C*07:661 |
|
615 |
P N |
N N |
FP Cl I |
Positive (76%) |
C*12:03 |
C*12:23 |
|
618 |
N P |
P P |
FN Cl I |
Not tested |
DQA1*03:02, - |
DQA1*03:01, - |
|
620 |
N N |
P P |
FN Cl I &II |
Cl I & II N |
|
|
Legend: Cl – Class, F – False, N - Negative P - Positive