High frequency of altered HLA class I phenotypes in laryngeal carcinomas

The exact frequency of HLA class I losses in human tumors is unknown. We ha ve previously shown that primary breast and colorectal carcinomas frequentl y lose HLA class I molecules (88% and 73%, respectively). Now we report tha t this phenomenon is also a frequent event in laryngeal carcinomas. Of a to tal of 76 laryngeal carcinomas analyzed, 66% of the tumors showed an altera tion in HLA class I phenotype. These altered HLA phenotypes were classified as total HLA loss (10.52%) (phenotype I); HLA-A locus-specific loss (13.15 %) (phenotype IIIa); HLA-B locus-specific loss (10.52%) (phenotype IIIb); H LA allelic loss (27.63%) (phenotype IV); and HLA-A and B locus loss (3.9%). Comparison of histopathological parameters with HLA expression showed that poorly differentiated tumors had the lowest levels of HLA class I expressi on (p < 0.05). Human Immunology 61, 499-506 (2000). (C) American Society fo r Histocompatibility and Immunogenetics, 2000. Published by Elsevier Scienc e Inc.