[Features of peripheral blood lymphocyte subpopulation profile in children with newly diagnosed untreated retinoblastoma].

Retinoblastoma is a malignant retinal tumor characterized by an aggressive clinical course, with frequent recurrences and the emergence of new foci even during chemotherapy.

Objective: This study investigated the subpopulation composition of peripheral blood lymphocytes in children with newly diagnosed untreated retinoblastoma.

Material and methods: A total of 24 children (48 eyes) were examined between December 20, 2023, and September 1, 2024; retinoblastoma was diagnosed in 28 eyes. Immunological assessment was performed using whole blood samples. Lymphocyte subpopulations were analyzed by flow cytometry on a BD FACS Canto II (Becton Dickinson, USA) using the Multitest 6-Color TBNK Reagent monoclonal antibodies in BD TruCount tubes (Becton Dickinson, USA).

Results: Analysis of the lymphocyte subpopulation profile revealed an imbalance in key cellular components of both the innate (natural killer cells, NK) and adaptive (T- and B-lymphocytes) branches of the immune system. Significant alterations were observed in NK lymphocytes (CD16⁺CD56⁺), with decreased absolute and relative counts identified in 54.5% and 45.5% of children, respectively. More severe disease stages were associated with marked abnormalities in NK cell populations and adaptive immune cell subsets (T- and B-lymphocytes); in this group, a reduction in the absolute number of NK cells was observed in 60% of patients, while nearly one-third of these children exhibited reduction in absolute and relative counts of B-lymphocytes (CD19⁺), as well as in key regulatory subpopulations of T-helper and T-cytotoxic lymphocytes.

Conclusion: The findings indicate significant deviations in the cellular immune status (lymphocyte subpopulation composition) of children with newly diagnosed untreated retinoblastoma.