Ethnopharmacological relevance: Aloe barbadensis Mill. (Aloe vera) is a widely used medicinal plant well reputed for its diverse therapeutic applications. It has been used for thousands of years in folk medicine to treat various conditions and the Aloe vera gel has been reported to possess anti-inflammatory as well as immunostimulatory and immunomodulatory properties. However, the mode of action is still unclear.
Aim of the study: The aim of this study was determine the effects of two well-defined A. barbadensis Mill. extracts AVH200® and AVE200 on human blood T cells in vitro.
Materials and methods: Peripheral blood mononuclear cells (PBMC) from healthy donors were stimulated polyclonally in the presence or absence of AVH200® and AVE200. The T cell phenotype was investigated by flow cytometry, cell proliferation was determined by CFSE dye and thymidine assay, respectively and cytokine secretion was determined by MSD® Multi-Spot Assay system and ELISA.
Results: The presence of AVH200® resulted in a reduced expression of CD25 among CD3(+) T cells and suppression of T cell proliferation in a dose dependent manner. Furthermore, AVH200® reduced the expression of CD28 on CD3(+) T cells. AVH200® also reduced the secretion of IL-2, IFN-γ and IL-17A in PBMC cultures. The AVH200® dose dependent reduction in T cell activation and proliferation recorded in the cell cultures was not due to apoptosis or cell death. Additionally, AVH200® was found to be more effective as compared to AVE200 in reducing T cell activation and proliferation.
Conclusion: AVH200® has the potential to reduce the activation, proliferation and cytokine secretion of healthy human blood T cells. Our study suggests that AVH200® has a suppressive effect on human blood T cells in vitro.
Keywords: Aloe barbadensis Mill.; Apoptosis; Cytokine; Proliferation; T cell.
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