Currently,immunotropic drugs are used in the modern strategy of cancer treatment. Importance is given to immunological markers of the tumor, which may be associated with the prognosis of the disease, the effectiveness of treatment. Therefore, the study of tumor immunophenotype is one of the leading scientific directions. Of particular interest is the study of the immunophenotypic characteristics of breast cancer depending on its biological subtype.

to evaluate the frequency of expression of HLA-I, HLA-II, CD71, MUC1,0 Pgp170 molecules by breast cancer cells and determine their relationship with the molecular biological subtype of the tumor.

This study included 120 patients with breast cancer who received treatment at the Federal State Budgetary Institution “N.N. Blokhin" Ministry of Health of the Russian Federation. Tumor stages II and III prevailed: 56.7% and 33.4%, respectively. A moderate degree of differentiation (G2) was more often noted. The luminal subtype was 58.3% (n=70), non-luminal - in 41.7% (n=50). Immunophenotyping of the primary tumor was performed by immunofluorescence 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. The frequency of expression of HLA-I, HLA-II, CD71, MUC1.0 Pgp170 molecules depending on the molecular subtype of breast cancer was studied.

Theabsence of molecules of the major histocompatibility complex of class I and II on breast cancer cells was found in 89.6% of the samples. In 23.4% of cases, their monomorphic expression was observed. In the luminal subtype, HLA-II class molecules were expressed somewhat more often: in total, mosaic and monomorphic types of reactions were observed in 30.5% (20/65) of cases. With non-luminal - 20.0% (10/47) of cases. The frequency of expression of the transferrin receptor is significantly higher in the luminal subtype than in the nonluminal subtype: 85.9% (n=5) and 65.2% (n=30), p=0.011. Luminal breast cancer cells express transferrin receptors predominantly monomorphically: 75.4% (n=49) versus 43.5% (n=20) in the non-luminal subtype, p=0.003. The percentage of monomorphically expressing MUC1 tumors is higher in luminal cancer: 83.3% (n=35) versus 65% (n=26) in the non-luminal subtype. Expression of Pgp70, namely monomorphic, is more often observed in luminal breast cancer.

. Luminal breast cancer is characterized by unfavorable prognostic immunophenotypic features. In the luminal subtype, expression of CD71 is more often observed, predominantly monomorphic. In the non-luminal subtype, expression of Pgp 170 is observed less frequently. No statistically significant differences between the molecular subtypes in terms of the level of expression of HLA-I and class II molecules were found.