title: High frequency of HLA-B44 allelic losses in human solid tumors.
abstract: Human leukocyte antigen (HLA) class I downregulation, a frequent phenomenon observed in a variety of human tumors, favors tumor immune escape from T-lymphocyte recognition. However, it is not known whether a particular HLA class I allele is lost more frequently than others. To address this question we analyzed HLA class I expression in tumor tissues derived from 300 patients diagnosed as having breast, colorectal, or laryngeal carcinomas. Cryostatic tumor sections and a broad panel of anti-HLA class I monoclonal antibodies were used. We found that the HLA-B44 allele was lost more frequently than other HLA class I alleles, and that the difference was not related with changes in HLA-B44 allele frequencies between patients and controls. In addition, we observed that 35% of the HLA-B44 negative tumors presented HLA haplotype loss associated with loss of heterozygosity. These tests were performed on DNA samples obtained from microdissected tumor tissues. The results seem to indicate that HLA class I allelic losses are not randomly distributed during tumor development but that some HLA class I alleles, and HLA-B44 in particular, are more frequently downregulated and may play an important role in immune escape mechanisms.
authors.affiliation: Departamento de Anáslisis Clínicos, Hospital Universitario Virgen de las Nieves, Universidad de Granada, Granada, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Cabrera
authors.forename: Isabel
authors.initials: I
authors.lastname: Maleno
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Lopez-Nevot
authors.forename: Maximino
authors.initials: M
authors.lastname: Redondo
authors.forename: Maria Angustias
authors.initials: MA
authors.lastname: Fernandez
authors.forename: Antonia
authors.initials: A
authors.lastname: Collado
authors.forename: Federico
authors.initials: F
authors.lastname: Garrido
mesh_terms: D000483:Alleles; D002277:Carcinoma / Q000235:genetics*; D015235:HLA-B Antigens / Q000235:genetics*; D059948:HLA-B44 Antigen; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D019656:Loss of Heterozygosity; D009369:Neoplasms / Q000235:genetics*
chemical_list: D015235:HLA-B Antigens; D059948:HLA-B44 Antigen; D015395:Histocompatibility Antigens Class I