Effect of Olive Leaf Extract on Cytokines Secreted by Macrophage

Herbal medicines in compared with chemical drugs have fewer side effects and can be a good medicinal alternative. The olive includes 20 different species of the family Oleaceae, with Olea europaea as the most recognized. Several studies have shown the immunomodulating effects of olive leaf extract. This study aimed to identify the immunoregulatory effect of olive leaf Sevillana variety on interleukins 12 and 10 which resulted from the murine macrophages in vitro.
In order to isolate macrophages, peritoneal macrophages BALB/C were used. To determine the cytotoxic effect of different concentrations of the olive leaf extract on macrophages, MTT assay was performed. Concentrations of 200, 100, 50, 25, 12.5, 6.25, and 3.1μg/ml in the time intervals of 12, 24, and 48 hours were evaluated. Three appropriate concentrations were selected to commence with the study of the determination of the amount of cytokines. Cell culture supernatant growth medium supernatant was collected at 12, 24, and 48 hours after adding the extract in order to examine the amount of cytokines. ELISA test was conducted using interleukins 12 and 10 measurement kits.
CC50 of the olive leaf extract at 12, 24, and 48 hours was 260.3, 170.5, and 150 μg/ml, respectively. According to the results, an increase in the concentration and duration of the study resulted in observable significant differences in the production of interleukins 10 and 12. As a result, the production of IL-10 and 12 experienced decreases and increases, respectively.
It seemed probable that the olive leaf extract had the capability to increase the production of IL-12 through activation of the classic macrophages and also deactivate the regulatory macrophages with an increase in IL-12 and a decrease in IL-10. Therefore, this can strengthen the immune system of the host in the early stages of infection. The other immunomodulatory effects of olive leaf must be considered by appropriate research.