Association Between HLA And Nasopharygeal Carcinoma

BACKGROUND:Nasopharyngeal carcinoma (NPC), one of malignant tumor in southern China, has a remarkably distinctive ethnic and geographic distribution. The highest incidence is found among southern Chinese (25-30 per 100,000 persons per year), especially those of Cantonese origin. In the year 2000, a total of 64,798 new cases were registered worldwide, and more than 80% of those were reported from China, Southeast Asia, and some Asian countries. In contrast, NPC is a rare malignant disease, with an incidence well under 1 per 100,000 persons per year in Caucasians from North America and other western countries.There are three major etiological factors, including genetic, environmental, and viral factors in NPC's development. Southern Chinese immigrants also have a higher risk of NPC as compared to the local western population. This suggests a strong association of NPC with genetic factors. Early linkage analysis on Chinese sib pair studies of NPC suggested the association of susceptibility HLA haplotypes with NPC development. HLA genes are highly polymorphic and encode for human leukocyte antigen (HLA) molecules that are essential for the presentation of foreign antigens to the immune system, including viral peptides. Class I HLA molecules (e.g., HLA-A and HLA-B) are expressed in all nucleated cells and are involved in the presentation of foreign antigens to cytotoxic CD8+ T cells capable of recognizing and lysing infected cells. Class II HLA molecules (e.g., HLA-DR, HLA-DQ, and HLA-DP) are...