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HOW PROFICIENT WE ARE IN KIR GENOTYPING? DATA FROM WORLDWIDE EXTERNAL QUALITY ASSESSMENT PROGRAM FOR KIR TYPING.
Raja Rajalingam Ph.D. , Marie Lau , Zeying Du , Arlene Locke , John Muramoto and Elaine F. Reed . ¹ UCLA Immunogenetics Center, Dept. of Pathology and Lab. Medicine, Los Angeles, CA .

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In 2004, the UCLA International Cell and DNA Exchange Program initiated an external quality assessment program to improve proficiency and standardize the KIR genotyping performed in Immunogenetics laboratories worldwide. We shipped sets of 4 DNA samples for 6 times at 3 months interval (total of 24 DNAs). These DNAs were selected on the basis distinct KIR genotype. The number of participating laboratories was initially 12, and now it is grown upto 50, which includes 10 basic research labs. Most laboratories performed gene-specific typing for 16 KIR genes using either commercial or in-house made PCR-SSP typing reagents. Some labs used either membrane or Luminex-based SSO method or multiplexed SSP method. The data submitted by different laboratories are assembled and the analyses were reported to all participating laboratories. Laboratories demonstrated proficiency in determining unique and rare KIR genotypes; however, difficulties occurred with interlaboratory reproducibility. Out of 16 genes tested, only 2DL4 and 3DL3 were typed correctly by all labs for all DNAs. Considerable variations between the laboratories were observed with the typings of 3DL2, 3DS1, 2DS4 and 2DL5. Two laboratories, using different methods (SSP vs SSOP) submitted allele-level typing for most inhibitory KIR genes, and discrepancies between their allele assignments were observed frequently. Overall, the data suggests that regular proficiency testing is necessary to assess the reproducibility and reliability of KIR genotyping.