Immunomodulatory effect of propolis extract on granzyme expression in cd8⁺ and cd4⁺cd25⁺ t cells

Objective: The purpose of this study was to explore the effect of propolis extract on CD8⁺ and CD4⁺CD25⁺ regulatory T cell populations and granzyme expression in both cell populations, as propolis has been suggested as an immunomodulatory agent. Materials and Methods: PBMC containing 1x10⁶ cells/ml from cervical cancer stage 3 patients were isolated and cultured with and without propolis extract. The cells were plated in a 24-well plate with RPMI medium supplemented with 10% FBS, 10 U/ml penicillin, 100 U/ml streptomycin, 2 mM L-glutamine and 50 μM 2-ME. Propolis extract was added (5, 10, 25 and 50 μg/ml) to PBMC culture. Negative control was made from PBMC culture without propolis extract for comparison. The cells were incubated for 48 hours in a 5% CO₂ incubator at 37ºC. The proportion of CD8⁺ and CD4⁺CD25⁺ regulatory T cells that expressed granzyme were measured by flow cytometry. Results: The results obtained that the level of CD4⁺, CD4⁺CD25⁺, and CD8⁺ T cells were not markedly depleted in propolis treatment in all doses compared to control group. The percentage of CD8⁺Granzyme⁺ and CD4⁺CD25⁺Granzyme⁺ were significantly different in groups of propolis treatment compared to control group. Conclusion: In summary, propolis extract may serve as an immunomodulatory agent in cervical cancer patients. Propolis extract could modulate the expression CD4⁺CD25⁺ T cells expressing granzyme and CD8⁺ T cells expressing granzyme while it has no effect on CD4⁺, CD4⁺CD25⁺, and CD8⁺ T cells.