Previous studies in our laboratory established that GTE suppresses B cell production of IgE without inducing apoptosis, in a homogeneous U266 B-cell model [11]. In this study, cell viability in PBMC was observed (>90%) on day 10 in the presence or absence of GTE to rule out cytotoxicity as a potential mechanism of GTE’s inhibitory

potential on IgE production and is in agreement with our earlier studies that GTE suppresses in vitro IgE responses without inducing apoptosis [11]. It has been demonstrated that green tea polyphenols, including epicatechin-3-gallate (ECG) and EGCG, exhibit anti-mutagenic and anti-carcinogenic activity in microbial systems, mammalian cell systems and in vivo [20]. Studies of Nakazato, et al. [21] reported that ECG has potential as a novel therapeutic agent for patients with B-cell malignancies (e.g. multiple myeloma), Y 27632 possibly through induction of apoptosis mediated by modification of the redox system [21]. GTE has been shown to inhibit breast cancer growth by a direct anti-proliferative effect on the tumour cells as well as by indirect suppressive effects on the tumour-associated endothelial cells [22] and

can increase the inhibitory effect of tamoxifen on the proliferation of the oestrogen receptor MCF-7, ZR75, T47D human breast cancer cells in vitro [22]. Studies of Silverberg et al. [23] found that GTE inhibits hydrogen peroxide-induced GSK2126458 datasheet necrosis of human skin fibroblasts [23]. In various tumour cell stiripentol systems, green tea polyphenols have been implicated in induction of apoptosis, via a caspase 3-executed mechanism

that targeted the mitochondria [24]. In other disease states, GTE also prevented Abeta [25]-induced activation of NF-κB, ERK and P38 MAP kinase pathways in rats, suggesting that GTE may prevent the development and progression of Alzheimer’s disease [25]. Green tea extract-4 (CSI-4) has also been reported to possess anti-adhesive activity against certain pathogenic bacteria (e.g. P. acnes), with no adverse effects against beneficial bacteria (e.g. Lactobacillus acidophilus) [26]. Previous studies of Nie et al. [27] demonstrated that green tea polyphenols and their major component, EGCG at a concentration of 200 microM, exert significant protective effects against 6-OHDA-induced PC12 cell apoptosis, and EGCG was more effective than the mixture of green tea polyphenols [27]. The authors concluded that green tea polyphenols’ neuroprotective effect was because of antioxidant function [27] and has potential for the treatment of neurodegenerative diseases [27]. In this study, addition of GTE (1–100 ng/ml) resulted in suppression of IgE (up to 98%); EGCG (0.5–50 ng/ml) alone moderately suppressed IgE production (up to 28%). Addition of cat pelt antigen (1 AU/ml) and GTE (1–100 ng/ml) or EGCG (0.