RESUMO
Objective: Full expression of class I HLA molecules on tumor cells is pivotal in priming the tumor antigen-specific CTLs for effective iramunotherapies. Tumor cells display abnonnal expression of HLA class I molecules in human ovarian carcinoma. Methods: In this study, the expression of class I molecules in human ovarian cancer cells was determined by using Western bloting, immunohistochemistry testing and flow cytometry. The mRNA of TAP (transporter associated with antigen processing) and LMP(low molecular weight polypeptide) were exannined at the same time by RT-PCR. Results: It has been shown that class I molecules were unable to be, or only weakly, expressed in five of eight ovarian cancer cell lines. On these cell lines abnormal in class I expression, no or only little mRNA were detected for TAP1, TAP2, LMP2 and(or) LMP7 genes. Class I expression, however, could be partially recovered by incubating the tumor cells at 25℃ when compared with those at 37℃ . Conclusion: The results suggested that the dysfunction of TAP and IMP genes, following by a defective expression of class I molecules, might be one of the mechanisms enable ovarian cancer cells to escape from immune surveillance.