13-P EpHLA-CONVERTER: A TOOL FOR AUTOMATIC INFERENCE OF HIGH-RESOLUTION HLA FOR SOLID ORGANTRANSPLANTATION. José Renato Barroso 1, Semiramis do Monte 2, Adalberto da Silva 3, Herton Sales Filho 2,Anaregina Araújo 2, Antonio Vanildo Lima 2, Deylane Oliveira 3, Rubens Santana 2, Marayza Carvalho 2, LuizClaudio Sousa 1. 1 Departamento de Computação, Universidade Federal do Piauí, Teresina, Brazil;2 Departamento de Clínica Médica, Universidade Federal do Piauí, Teresina, Brazil; 3 Departamento deBiologia, Universidade Federal do Piauií, Teresina, Brazil.

Aim: Here, we describe the web-based tool EpHLA-Converter, a free program designed to reduce the com-plexity of the problem to predict high resolution HLA typing.

Methods: Our program allows one to determine the most probable high-resolution HLA class I and II geno-types using as data input just low- or medium-resolution HLA-A, -B, -C, -DRB1, -DRW, -DQA1 and -DQB1 typ-ing and the population it came from. Allelic conversion is based on public databases (NMDP, IMGT) queriesand allele frequencies determined from either reference populations or private HLA typing databases. Theprogram was developed to run independently or to be integrated to third part programs including therecently developed EpHLA program to analyze epitopic HLA serum reactivity. We validated the EpHLACon-verter to HLA class II inference by using three different approaches: (i) We determined the percentage ofmatched results between the 100 predicted high-resolution typing with the actual high-resolution typingto HLA-DRB1, (ii) the concordance to predict HLA-DQA1 and HLA–DQB1 assignments by using NMDP pub-lished DRB1/DQB1/DQA1 associations and (iii) by computing the time spent in the conversion from medium-to high-resolution HLA- A, -B and -DRB1 typing for database with more than 10,000 typings each one.

Results: Percentage matched predicted High-Resolution vs. Actual High-resolution typing for HLA-DRB1and –DQB1 was 94% and 83%, respectively. Besides, we showed that our tool is able to safely convert HLA typ-ing databases with 10,000 typings HLA-A, -B –DRB1 in 191 minutes (more than five inferences per second).The limitation of the EpHLA-Converter program is if the allele DRB1 is uncommon, the association HLA-DRB1/DQA1/DQB1 will not be able to be inferred because the association is not listed on the available fre-quencies tables.

Conclusions: Our data demonstrates that EpHLA-Converter has an excelent accuracy rate to predict DRB1and DRB1/DQA1/DQB1 association at high resolution level.

14-P IS THERE A ROLE FOR THE ELISA TEST IN HLA ANTIBODY SCREENING?. Marilyn P. Downs, Jerry L. Morrisey,Sandra L. Smith. HLA Lab/Pathology, Scott & White Healthcare, Temple, TX, USA.

Aim: The trend to HLA antibody testing by multiplex immunoassays has led us to question the current roleof the ELISA test in our HLA antibody screening. HLA antibody testing algorithms are used for efficiency andfor standardization. The ELISA test has been part of the screening route.

Methods: Routine HLA antibody screening is the first step of the algorithm. Initially, our lab used cytotox-icity and ELISA tests for HLA antibody screening. We currently screen renal candidates’sera by ELISA Class Ialternating with the Luminex Class I/II screen methods. The conflicting results require follow-up tests.

Results: In the ASHI Proficiency survey, less than 10 labs are reporting results by the ELISA method, thusthe results are not graded. The ELISA Class I Screen is cost effective for periodic PRA screening of our renalwaitlist patients. We have observed results on some sera that tests positive on ELISA and then negative ona luminex screen. These patients(< 10% of all listed patients) exhibit high background on luminex platform.Conversely some patients’ sera test positive on the luminex screen and negative on the Elisa screen. The con-flicting results could lead to confusing interpretation; however, in those patients with an established (3 to 6succesive screens) negative, the change to positive or indeterminate has indicated a change in patient healthor a sample discrepancy.

Conclusions: A review of our results on ELISA screens over the past five years, (2007 through 2012) inde-terminate or repeated tests were observed to be lot dependent, more than tech dependent. The current algo-rithm includes ELISA Class I screen, luminex screen (ClassI/II), and luminex single antigen tests. Theelimination of this ELISA test is being considered as the more specific luminex screen result contributes infor-mation, including Class I and II antibody simultaneously. Although a reliable test methodology, the reductionin reagent cost, QC and proficiency on this less sensitive test would be a benefit of elimination.

60 Abstracts / Human Immunology 74 (2013) 51–173