Loss of MHC Class-I Expression in Cervical Carcinomas

The expression of MHC class-I antigens was analysed in 67 cervical carcinoma biopsies; 16% of the biopsies showed complete or heterogeneous loss of HLA expression as judged by reactivity with antibodies recognizing monomorphic determinants of the class-I heavy chain bound to beta 2 microglobulin (beta 2m). In addition, other biopsies showed a loss in expression of particular allelic products: 23% for HLA-A2; 17% for HLA-A3; 23% for HLA-Bw4 and 19% for HLA-Bw6. Three biopsies showed changes at 2 alleles, 2 of which were at both HLA-A and -B loci. Down-regulation of class-I expression may be virally mediated and HPV DNA is frequently found in cervical carcinomas. However, there appeared to be no direct correlation between the detection of HPV 16 or 18 DNA in these tumours and changes in HLA expression. There was also no correlation with the expression of the oncofoetal antigen 5T4. Our results show that a significant proportion (at least 30%) of the cervical carcinomas showed some alteration in MHC class-I expression. Such changes may allow tumours to evade immune surveillance with more rapid progression. There was, however, no correlation with tumour type, degree of differentiation or stage of disease at presentation.