T cell regulation by Phlomis lanata protein extracts in mice

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.