T cell regulation by Phlomis lanata protein extracts in mice

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Context: Phytopharmacology is a complex but very promising research area. The different plant parts and extraction methods may result in opposed effects. Phlomis species have been reported for both anti-inflammatory and tonic properties.Objective: The effect of Phlomis lanata Willd. (Lamiaceae) protein extracts on immune cell reactivity was studied in the experimental mouse model.Materials and methods: Protein extracts from P. lanata aerial parts were fractionated by Q-sepharose ion-exchange chromatography and applied to whole spleen cells or T-cell subsets at 5 μg/ml. Cell growth and cytokine production were evaluated after 4 and 2 d of culture using 3H-thymidine-uptake and ELISA techniques, respectively.Results: Among the protein fractions tested, column wash proteins (W1) and the fraction eluted using 600 mM NaCl (F6) reduced by 76% and increased by 78% spleen cell proliferation, respectively. W1 suppressed proliferation of effector T-cells, but stimulated the growth of suppressor/regulatory cells by 62–148%. Although W1 stimulated IL-2 and IL-10 production from total spleen cells, it significantly increased IL-10 (50%) and reduced IL-2 (30–50%) production from T-cells, while TNF-α release was enhanced in CD25+CD4+ by 92% and reduced by 50% in CD25+CD8+ cells. F6 stimulated whole spleen cell growth, reduced proliferation of CD8+ and CD25+ cells by approximately 50%, while decreasing by 60–80% TNF-α production from CD25− and CD25+CD8+ cells.Discussion and conclusion: The suppressive activity of W1 could be attributed to IL-10 and TNF-α, while the stimulatory effect of F6 could be attributed to the inhibition of T-regulatory cells. In the same plant, coexisting protein fractions induce both immunostimulatory and immunosuppressive activities.