Comprehensive analysis of B cell and follicular T cell subpopulations in human palatine tonsils

I ntroduction. Palatine tonsils play an important role in protecting the human body from numerous pathogens entering through the upper respiratory and digestive tracts. One of the main components of the protective function of the palatine tonsils is the formation of humoral immunity, which occurs as a result of a B-cell response to foreign antigens with the participation and under the control of follicular T cells. Disorders in the involvement of B and T cells in the immune response in the tonsils may be associated with various pathologies, chronic infections, immunodeficiency or lymphoproliferative diseases. Aim. To perform a methodical analysis of various subpopulations of B and follicular T cells in tonsils using flow cytometry. To evaluate various components of the local immune response. Materials and methods. The selection of patients for the study was carried out in the otorhinolaryngological department of the City Clinical Hospital No. 1 named after N. I. Pirogov, Moscow from 2024 to 2025. Fresh tonsils were obtained from patients undergoing tonsillectomy or tonsillotomy. Mononuclear cells (MNCs) isolated from the organs were stained with a mixture of surface markers for Band T-follicular cells, followed by intracellular staining of the transcription factors Bcl6 and FoxP3 for subsequent flow cytometry analysis. Results and discussion. Based on the obtained data, a strategy was proposed for identifying key B-cell subpopulations (naïve, double-negative B cells, memory B cells, and germinal center (GC) B cells) involved in the humoral immune response in tonsils. Additionally, an approach was developed for analyzing T-follicular cells in tonsils, distinguishing subpopulations of T-follicular helper (Tfh) cells, T-follicular regulatory (Tfr) cells, and CD25++ Tfh cells, which are essential for the control and regulation of B-cell responses. Conclusions. The developed analysis can be used both in basic research and in clinical practice for the diagnosis and monitoring of immunopathological conditions.