166-P WOULD BE HLA-C⁄15 GENE RELATIONED WITH THE RESISTANCE OF DUST MITES SENSITIVE INDIVIDUALS?Edson Guilherme, Dina L.M. Falavigna, Ariella A. Marchioro, Marcela C.C.L. Carniatti, Ana L.F. Gulherme, LuizaT. Tsuneto. Basic Sciences of Heath, University State of Maringa, Maringá, Parana, Brazil.

Aim: Atopic diseases are related to the production of IgE to certain allergens, but the genetic control of thisshift has not been clearly elucidated. atopic mite (Dermatophagoides farinae, Dermatophagoides pteronyssi-nus, Blomia tropicalis) has a particularly important relationship in the development of asthma in children andhypersensitivity in young adults. The main feature of the HLA system is the high degree of polymorphism andits crucial role in the immune response against unrelated agents to the host. HLA surface molecules interactwith CD4 + T cells in turn to release cytokines that mediate the Th1 or Th2 response. The aim of this study is toassess the influence of HLA genes in susceptibility/resistance of individuals sensitized to mites.

Methods: In this case-control study 108 patients sensitized to mites were compared with 66 individualswho did not show sensitization to mites. All samples were typed for the loci HLA-A, HLA-B, HLA-C andHLA-DRB1 by PCR-SSO (polymerase chain reaction- sequence specific oligonucleotides) by LUMINEXmethods.

Results: No significant result was observed between sensitized and unsensitized individuals between thealleles of the loci HLA-A, HLA-B, HLA-C and HLA-DRB1, except HLA-C⁄15 that showed a negative associationbetween patients (2.8%) and controls (15.2%), with p = 0.0051, OR = 0.16, CI = 0.03 to 0.67).

Conclusions: In this study we suggest the involvement of HLA-C gene as a protective gene to dust mite ato-pic patients.

167-P A ONE-PASS DNA SEQUENCING STRATEGY AT RECRUITMENT OF HEMATOPOIETIC STEM CELL DONORS –RETHINKING TYPING REQUIREMENTS. Bin Tu, Nuri Cha, Phillip Posch, Jennifer Ng, Carolyn K. Hurley. CW BillYoung Marrow Recruitment and Research Program, Georgetown University, Rockville, MD, USA.

Aim: In order to reduce the time required to identify a match for unrelated donor hematopoietic stem celltransplantation, a one-step DNA sequencing strategy was employed at the time of recruitment. The impact ofthis strategy on typing resolution and the effect of current registry requirements on resolution and coding ofassignments were evaluated.

Methods: Sanger-based DNA sequencing was used to obtain diploid exons 2 and 3 HLA-A,-B,-C assign-ments of 2,746 unrelated African American volunteers at recruitment.

Results: The results are high resolution; using IMGT/HLA database 2.28.0, �90% of donors carried 3 or lessalternative genotypes (e.g., 89% HLA-C). Of those individuals whose HLA typing resulted in alternative geno-types, the majority (�90%) were predicted to have only a single ‘‘common’’ genotype among the alternatives.Higher resolution typing confirmed these predictions. A small percentage of all assignments (3.4% A, 8.6% B,3.9% C) included greater than two antigen groups. For HLA-B, only 4 of the 48 unique haplotypes with >2 anti-gens included two common genotypes, impacting only 18 of the 2746 individuals. The need for secondaryassays to resolve these few combinations at the time of recruitment is questionable because of the high res-olution of the screening-level typing, the focus on matching alleles not antigens, the additional cost, theincreased opportunity for errors, and the less robust nature of the secondary assays. The assignment ofNMDP-designated allele codes reduced the resolution substantially and introduced genotypes that werenot included in the laboratory’s assignments.

Conclusions: We suggest an alternative strategy: use the exons 2-3 diploid sequence as the assignment toavoid the limitations mentioned above, as well as to ‘‘immortalize’’ the assignment in time regardless of theintroduction of novel alleles. To keep pace with current donor selection criteria and with the increasing num-ber of new alleles, it is time to rethink our recruitment typing strategies.

152 Abstracts / Human Immunology 73 (2012) 49–167