Interrelation of HLA-I and class II major histocompatibility complex molecules with clinical and morphological signs of breast cancer: A retrospective cohort study

Background. For a long time, interest in the HLA peptide complex is unabated, the clinical significance of which in cancer is still the subject of intense debate. Through the presentation of HLA antigens, tumor cells become available for recognition and destruction by effector cells of the immune system. A detailed analysis of the expression status of HLA molecules by breast cancer cells is of both scientific and important practical value. It can provide additional information about the immune system to determine a further strategy for treating breast cancer.

Aim. To evaluate the frequency of expression of HLA-I and class II molecules by breast cancer cells and to determine its relationship with the morphological and clinical characteristics of the tumor.

Materials and methods. This study included 82 patients with breast cancer who received treatment at the Blokhin National Medical Research Center of Oncology. Immunophenotyping of the primary tumor was performed by the immunohistochemical method (immunofluorescent staining) on cryostat sections. The reaction was evaluated using a ZEISS luminescent microscope (AXIOSKOP, Germany). The frequency of expression of HLA-I and class II molecules was studied depending on the clinical and morphological characteristics of breast cancer.

Results. It was found that the frequency of expression of HLA I and II class molecules by breast cancer cells differed. HLA class I antigens are preserved in almost half of the cases 54.5%, while HLA class II antigens are preserved in 22.0%. Associations of molecules of the major histocompatibility complex with clinical and morphological signs of breast cancer were revealed. The frequency of HLA-DR negative cases increases in the stage advanсed (p=0.029). The frequency of monomorphic expression of HLA class II with T1 tumor was 50% versus 0% at T4 tumor (p=0.032). Estrogen receptor-negative tumors in most cases did not express HLA-II class (85.2% vs 64%; p=0.034). No connection with other clinical and morphological features of the tumor has been established.

Conclusion. In most cases of breast cancer, the expression of HLA class II molecules is lost, while the expression of HLA class I is preserved in half of the cases. Monomorphic expression of HLA class II is characteristic of the early stage of breast cancer development and predominantly of receptor-positive tumors.