Analysis of the lymphoid tumor microenvironment (TILs) in breast cancer by flow cytometry

Despite the success in early diagnosis and drug treatment of breast cancer patients, long-term treatment results are still unsatisfactory, and in this regard, the role of research aimed at studying various mechanisms of development of this disease is increasing. It has been established that the degree of tumor infiltration by immune cells and their composition are directly related to the development of the disease and the response to therapy. Multiparameter flow cytometry (PC) allows studies of the subpopulation composition of TILs. The aim of the work was to study the features of the lymphoid microenvironment (TILs) of tumors in patients with primary operable and locally advanced breast cancer by PC. The study included patients with primary operable breast cancer (group 1, n = 121) and locally advanced (group 2, n = 80) receiving treatment at the N. N. Blokhin NMRCO. The TILs of a tumor obtained intraoperatively or by a core-biopsy were examined. The patients were divided into 3 subgroups: 1 subgroup – the degree of infiltration up to 1%, 2 subgroup – the degree of infiltration from 1 to 10%, and 3 subgroup – the degree of infiltration over 10%. Patients of group 1 were characterized by high functional activity and concentration of effector cells with a low degree of tumor infiltration, and as the number of lymphocytes in the tumor increased, an increase in the pool of CD4+ cells and CD4 Treg was noted simultaneously with a decrease in the number and functional activity of effector TILs. In group 2 were no significant differences in the cellular composition of TILs in subgroups with a weak and moderate degree of infiltration, and a variant with infiltration of more than 10% was recorded in only one patient. The lack of association of the TILs subpopulation structure in subgroups with varying degrees of tumor infiltration indicates a similar nature of the local immune response in locally advanced breast cancer.

Thus, unlike patients with locally advanced breast cancer, patients with primary operable breast cancer show a change in the type of local immune response from effector to regulatory. A high degree of tumor infiltration is characterized by depletion of effector cell function.

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