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inflammatory model of Freund's adjuvant-induced arthritis, considered as the best available model of rheumatoid arthritis, tea showed a profound degreeof anti inflammatory activity in both the primary and secondary phase This proccdure has been proposcd by severa immunosuppressive activity It has been proposcd ed that those anti-infammatory compounds capable of inhibiting secondary lesions can be considered as immunosuppressive agents.| In this model of immunologically mediated chronic snovial inflammation and arthritis, macrophages play a central role. After activation, they are capable of synthesizing mediators such as PGE, and cytokines such as TNF-z and IL-1. In turn, these synthetic products induce the production of variety of enzymes which initiate cartilage and bone destruction. Indomethacin 51.2% and 45.26%. respectively. on 5th dax. which indicates its action in the primary phase [Table 6]. Dexamethasone showed most significant inhibition on 5h and 21" day Tables 6 and 7]. Black tea (10%, 20%) decoction at above mentioned doses showed a maximum inhibition of 38.56%, and 69.53%, respectively, and was statistically significant Table 6]. Therefore, tea definitely has some effects on the immunological and systemic secondary phase of adjuvant arthritis.
Finally, to examine another aspect of its immune modulatory action, a Iymphoproliferative assay was undertaken with black tea decoction. Stock solution was made to 20%. The degree of proliferation was measured by two approaches, namely the MTT assay and Trypan blue dye exclusion assay [Figures 1 and 21. MTT is methyl thiazolyl tetrazolium, a yellow compound, which in the presence of mitochondiral dehydrogenase is converted into formazan which is purple in color. As only living cells produce this enzyme, by performing this assay, the amount of living cells may be assessed. Hence the grea
formazan produced, more will be the optical density (O.D). This represents a greater number of living cells. Different concentrations of tea ranging from 20% to 1% were used. As is evident from Figure 1, maximum proliferation was observed at the maximum concentration used, ie. 20%. Subsequently with lower concentrations, the degree of proliferation was less. From this experiment, we can firmly conclude that tea has stimulatory effects on Tlymphocytes, and in 72h gave the best time kinetics. Due to economic constraints, we could not use a mitogen in this study.
The results obtained by the MTT assay were corroborated with a cell count assay using Trypan blue, based on the known principle that Trypan blue enters only nonviable, ie. dead cells The cell count assay showed a similar profile
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in which maximum proliferation was observed at 72 h [Figure 2] using the highest concentration of tea. Black tea (20%) decoction displayed maximum immunomodulatory (immunostimulatory) properties in our in ritro system.ij
Taken together, our data indicate that black tea has potential acute and chronic anti-inflammatory action. This corroborates with the current trend of tea being promoted as 'health drink'. Our results support the idea that tea has a beneficial effect. Significant antiarthritic activity was observed with regular administration of black tea 10% and 20% in the Freund's adjuvant-induced model of arthritis. Roy d al, stated that chronic treatment with Black tea (in arthritic rats) resulted in a decrease of paw diameter and tissue lipid peroxidation, along with a restoration of GSH, and Fernando hdhor blck t
gastric ulcer healing activity which is mediated ria multiple mechanisms 24
However, such a study would be diffcult to undertake in humans as the majority of the population are 'tea consumers'. Hence, we propose that after a 'wash out period of 4 weeks, preliminary studies can be undertaken with normal healthy volunteers.