T cell regulation by Phlomis lanata protein extracts in mice

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.

The effect of Phlomis lanata Willd. (Lamiaceae) protein extracts on immune cell reactivity was studied in the experimental mouse model.

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 (3)H-thymidine-uptake and ELISA techniques, respectively.

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.

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.