Abstracts S32 124 125 HLA ALLELES IN ISOLATED POPULATIONS FROM NORTH HLA-DPB1* POLYMORPHISMS IN GREEK POPULATION SPAIN: ORIGIN OF THE BASQUES AND THE ANCIENT IBERIANS. Katerina E. Tarassi, Diamanto I. Kouniaki, Theophilos I. Athanassiades, Chryssa A. Papasteriades. Pablo Sánchez-Velasco2, Eduardo Gómez-Casado1, Jorge Martínez-Laso1, Immunology - Histocompatibility Dept, Evangelismos Hospital, Juan Moscoso1, Jorge Zamora1, Ernesto Lowy1, Carlos Silvera-Redondo1, Athens, Greece. Alberto Cemborain2, Francisco Leyva-Cobián2, and Antonio Arnaiz-Villena1. 1Department of Immunology and Molecular Biology, Hosp. 12 de Octubre, Since the number of HLA-DPB1 identified alleles is continuously increasing Universidad Complutense, Madrid, Spain. E-mail: [email protected]. and their clinical relevance, particularly in Bone Marrow Transplantation, is 2Department of Immunology. Hospital Universitario Marqués de established, the aim of this work is to present the HLA-DPB1 polymorphism in Valdecilla. 39008 Santander, Spain. Greeks. The population studied consisted of 140 unrelated, unselected healthy individuals of Greek origin. Sixty-eight (68) of them were typed for HLA-A, -B, -DRB1, -DQA1 and -DQB1 alleles have been studied in three DPB1*0101-1901 using oligonucleotide typing, whereas 72 were typed for all relatively isolated populations of northern Spain from Cantabria (Pas Valleys known DPB1 alleles by PCR-SSOP and/or PCR-SSP. inhabitants or Pasiegos and Cabuernigos) and from the Basque Country (Arratia The DPB1* alleles detected are presented in the following table: Valley inhabitants). These populations have been compared to other neighbouring ones and other Mediterraneans by using neighbor-joining DPB1 Freq % DPB1 Freq % DPB1 Freq % dendrograms, plane genetic distances, correspondence and HLA haplotype (N=140) (N=140) (N=72) analyses. These populations are more related each other than to Spaniards and 0101 7.1 1101 5.7 2001 1.4 also are genetically close to North Africans. Pasiegos show a slight degree of 0201 40.0 1301 5.0 3101 1.4 admixture with central and western Europeans. The most feasible origin of these 0301 7.1 1401 1.4 3301 1.4 populations is regarded as being a remnant of the primitive Spanish population 0401 58.6 1601 2.1 3501 2.8 (ancient Iberians) or otherwise of North African refugees that could have 0402 33.6 1701 3.6 3701 1.4 occupied the area before their expulsion by the Catholic Kings after 1492 AD, 0501 1.4 3901 1.4 when North Africans definitively were expelled. The first theory is more favoured since there are no records of a permanent Muslim invasion in these 0801 0.7 5001 1.4 areas during Middle Ages. 0901 0.7 5101 1.4 1001 4.3 6001 1.4 Conclusions: In comparison to the data from the 11th and 12th IHW 1) DPB1*0201, 0401, 0402 are the most frequent alleles in Greeks, as in other Caucasians, but DPB1*0201 shows the highest frequency among all populations studied, 2) DPB1*1301, characterizing Blacks and Orientals, is presented in Greeks with the highest frequency among Caucasians (except Gypsy Spanish). So, it seems that DPB1* alleles distribution in Greeks show certain peculiarities, as we have also found in other HLA loci studied. Poster Group 9 - Immunogenetics of Disease 126 127 THE ORIGIN OF SOUTHERN SIBERIA TUVINIANS: A COORDINATED DOWNREGULATION OF APM COMPONENTS POPULATION WITH BOTH ORIENTAL AND CAUCASOID IN MHC CLASS I-DEFICIENT METASTATIC TUMOUR CHARACTERISTICS. VARIANTS IMMUNOSELECTED BY T LYMPHOCYTES Jorge Martínez-Laso2, Marina Sartakova1, Luis Allende2, Marisol Martinez, Angel M. Garcia-Lora, Ignacio Algarra*, Eva Jimenez and Vladimir Konenkov1, Juan Moscoso2, Carlos Silvera-Redondo2, Federico Garrido Serv. Analisis Clinicos, Hospital Univ. Virgen de las Nieves, Arancha Pacho2, Jorge Zamora2, Ernesto Lowy2, Eduardo Granada, Spain. *Dep. Ciencias de la Salud, Univ. de Jaén, Spain Gómez-Casado2, and Antonio Arnaiz-Villena2 1 Laboratory of Immunogenetics, Institute of Clinical Immunology, 630091 Our previous studies with the GR9 tumour model had shown that the MHC class Novosibirsk, Russia I phenotype of the metastatic tumour variants differs depending on the immune 2 Department of Immunology and Molecular Biology, H. 12 de status of the host: MHC class I-negative in immunocompetent BALB/c mice Octubre, Universidad Complutense, Madrid, Spain. E-mail: and MHC class I-positive in immunodeficient (nu/nu) mice. The results showed that in this tumour model the major factor contributing to the appearance of [email protected]. MHC class I-negative tumour variants is T cell immunoselection. HLA class I and class II alleles have been studied for the first time in the To explore the molecular mechanisms involved in the origin of these MHC Turkish-speaking Tuvinian population, which lives in Russia, North of class I-deficient tumour variants in our fibrosarcoma model, we analyzed the Mongolia and close to the Altai mountains. Comparisons have been done with expression of different components of the MHC class I antigen-processing about 11000 chromosomes from other worldwide populations, and extended machinery (APM). haplotypes, genetic distances, neighbour joining dendrograms and The MHC class I stability assays at 26ºC in the presence of exogenous 2- correspondence analyses have been calculated. Tuvinians show an admixture of microglobulin showed a partially recovered the cell surface expression of H-2 Mongoloid and Caucasoid characters, the latter probably coming from the class I molecules. Semiquantitative RT-PCR of different APM components ancient Kyrgyz background or, less feasibly, more recent Russian Caucasoid showed the constitutive expression of TAP-1, TAP-2, LMP-2, LMP-7, LMP-10, admixture. However, Siberian population traits are not found and thus Tuvinians tapasin and calnexin was downregulated in the B9 tumour clone as well as in all are closer to Central Asian populations. Siberians are more related to Na-Dene metastatic nodes obtained from immunocompetent BALB/c mice. Interestingly, and Eskimo American Indians; Amerindians (from nowadays Iberian-America) this was not the case for the nu/nu BALB/c-derived metastases. In conclusion, a are not related to any other group, including Pacific Islanders, Siberians or other coordinate transcriptional downregulation of multiple components of the APM American Indians. The `more than one wave' model for the peopling of the is responsible for the absence of H-2 class I antigen surface expression in Americas is supported. metastatic nodes generated in immunocompetent BALB/c mice. Genes and Immunity Abstracts S33 128 129 DIFFERENT IMMUNOGENICITY AND PATTERN OF LOCAL MOLECULAR MECHANISMS INVOLVED IN THE TOTAL GROWTH IN METASTATIC TUMOUR VARIANTS THAT LOSS OF HLA CLASS I IN COLORECTAL TUMORS: 2M ARE/ARE NOT IMMUNOSELECTED BY T LYMPHOCYTES INACTIVATION AND LMP7 DOWNREGULATION. Marisol Martinez, Angel M. Garcia-Lora, Ignacio Algarra*, Eva Jimenez and Carmen M. Cabrera, Pilar Jiménez, Teresa Cabrera, Francisco Ruiz- Federico Garrido Servicio de Analisis Clinicos, Hospital Universitario Virgen de las Cabello, Federico Garrido. Servicio de Análisis Clínicos. Hospital Nieves, Granada, Spain. *Departamento de Ciencias de la Salud, Universitario Virgen de las Nieves. Granada. Spain. Universidad de Jaén, Jaén, Spain The mechanisms to produce loss of MHC class I expression, in different types of tumors are partially known. Accordingly, we have studied colorectal tumors We previously reported that metastatic cell lines obtained in immunocompetent to elucidate the specific mechanisms evading T-cell immunoresponse. BALB/c mice have a H-2 class I-negative phenotype similar to that of the We have selected tumors with total loss of MHC class I expression by inducing fibrosarcoma tumour cell clone from which they derived. In contrast studying 124 colorectal tumors with immunohistochemical staining with anti when immunodeficient (nu/nu) BALB/c mice were used to produce metastases, HLA monoclonal antibodies (mAb). 14 tumors out of 124 (11%) exibit a 100% of the metastasis-derived cell lines were H-2 class I-positive for Kd, Dd phenotype with HLA class I total loss. Microsatellite instability (MSI) analysis and Ld molecules. The results showed that in this tumour model the major was also carry out in the same tumor samples. The expression of β2- factor contributing to the appearance of MHC class I-negative tumour variants is microglobulin, HLA-A, B, and C, TAP1, TAP2, LMP2, and LMP7 were T cell immunoselection. analysed using RT-PCR in microdissected tumor samples. 4 out of 14 MSI To determine the biological behaviour of these metastatic tumour variants we positive (MSI+) and W6/32 mAb negative tumors, showed biallellic inactivation performed local growth and immunogenicity studies. Different metastatic cell of β2m and accumulation of HLA heavy chain in the cytoplasm. MSI negative lines were injected subcutaneously into the footpad in syngeneic (MSI-)/W6/32 mAb negative tumors presented alterations in the expression of immunocompetent BALB/c mice. components of the antigen processing machinery (APM). 9 out of 10 tumor The results showed a different pattern of local growth: H-2 positive metastatic samples showed downregulation of LMP7 gene, and 4 out 10 presented TAP2 cell lines derived from nu/nu mice grew slowly, reaching a maximum of 5 mm disregulation. This group apparently expressed normal levels of heavy chain and of diameter after 15 days, then regressing and been rejected after a short period 2m proteins. of time (25 days). The H-2 negative metastatic cells (derived from