Background: Cervical intraepithelial neoplasia (CIN) and cervical cancer have been shown to be strongly associated with infection by human papillomavirus (HPV). However, other factors may be contributory in the progression from normal epithelium to CIN and cervical cancer, since not all women with HPV infection develop disease. Recently, it was demonstrated that there is a high risk for cervical cancer and CIN in women with HLA DQB1 * 03 (RR = 7.1, p < 0.0009) (1). Subsequent reports have been conflicting, due to sample size, genetic heterogeneity and differences in the techniques employed for the detection of HLA DQB1 * 03.
Materials and methods: DNA from cervical smears of 178 women with CIN and 420 controls with normal cervical cytology was analyzed by polymerase chain reaction (PCR) with type-specific primers for HPV 16, 18, 31, and 33. The DNA from test and control samples were also analyzed by a novel PCR technique, which mutates the first base of codon 40 (DQ alleles) from T to G to create an artificial restriction site for an enzyme Mlu I that distinguish DQB1 * 03 from other alleles and are confirmed by digestion of amplified DNA with Mlu I. Further analysis of individual DQB1 * 03 alleles was performed using PCR and allele-specific primers.
Results: One hundred forty-four (34%) out of 420 controls (all HPV 16, 18, 31, or 33 negative and normal cytology), 37/66 (56%) of CIN I and 72/112 (64%) of CIN III were positive for DQB1 * 03 (trend test, p < 0.001, chi 2 = 37.3). A significant association was observed between DQB1 * 03 and CIN (odds ratio 3.03; 95% CI 2.11-3.45). Of women with CIN, 131/178 (73.5%) had HPV (types 16, 18, 31, or 33) infection. There was a significant association between DQB1 * 03 and presence of HPV (odds ratio 3.43; 95% CI 2.25-5.10). Homozygosity for DQB1 * 03 was more strongly associated with CIN than heterozygosity (odds ratios 4.0 and 2.63, respectively); and for the presence of HPV (odds ratio 4.47; 95% CI 2.58-7.77). HLA DQB1 * 0301 was the most strongly associated allele with CIN and HPV (odds ratios 2.53 and 2.63, respectively).
Conclusions: HLA DQB1 * 03 is associated significantly with CIN and may be permissive for HPV infection. Further analysis of class II HLA typing in CIN is necessary to evaluate this association.