This may indicate that the exosomes carry information that together with IL-2 can induce resting T cells to respond similar to the cells that secreted them. The chemokine CCL4, also known as macrophage inflammatory protein 1b, has previously been shown to be secreted by CD8+ T cells which supports the notion of a preferential stimulation of cytotoxic T cells as also indicated by the shift in CD4/CD8 ratio. The cytokine profile of cells stimulated with exosomes+IL-2 reveals a high level of IL-5 and IL-13, which may indicate a Th2 skewing of the activated cells. In addition the exosomes seem to carry with them large amounts of CCL5, since the addition of exosomes to the culture media makes this cytokine immediately readily detectable. Interestingly RANTES has been shown to be secreted by activated CD8+ T cells from a specific storage compartment with exosome properties and exosomes carrying RANTES can actively inhibit HIV infection. There is also a previous report demonstrating that RANTES is present in CD8+ cytotoxic cell granules and that it can act as a mitogen upon cell surface aggregation followed by secretion of MIP-1b. These results correspond well with our observations. In summary, our result show that exosomes secreted from simulated CD3+ T cells can dramatically change the response of resting autologous T cells to IL-2. The exosomes carry RANTES and seem to favor a cytotoxic response, which could be of potential interest in anti-viral and anti-tumor treatment. The emphasis on studying the interaction of methylxanthines such as theophylline, PLX-4720 theobromine and caffeine with nucleic acids is mainly because of a) its dietary consumption b) their use as therapeutic agents. Interestingly these xanthine derivatives have interactions with steroid-receptor complex, DNA, RNA, adenosine receptor, protein kinases, and neurological behavior which are reckoned to be pivotal for their ability to modulate the biochemical reactions by interacting with the nucleic acids or through cell signaling molecules. While probing the spectroscopic analysis of methylxanthines interaction with nucleic acids, it has been understood that caffeine known to interact with 59-adenosine monophosphate and poly riboadenylate by a parallel arrangement outside-stacked selfassociation to DNA bases, and report from Nafisi et.al, indicate that caffeine and theophylline bind to DNA in aqueous solution. However a comparative analysis of caffeine, theophylline with the other structurally related compounds like theobromine has not yet been shown to understand their variance in binding efficacy with DNA, as all of them are having vital cellular activities. Moreover, the current study deals the binding interaction of all these three methylxanthines with DNA in the presence of divalent metal ions and during helix-coil transition state holding some key rationales are explicitly explored in detail. As far as the importance of theobromine is concerned it has been shown that theobromine enhanced the antitumor activity of adriamycin with reduced toxicity. It has also been reported that caffeine and theobromine inhibited the doxorubicin efflux from tumor cells and increased the tumoricidal activity with reduced side effect. From our earlier reports it could be understood that since xanthine derivatives can interact with DNA, they can reduce the DNA-directed toxicity of certain intercalating dyes such as ethidium bromide, acridine orange and antitumor agents like cisplatin, novantrone, actinomycin D etc. Moreover, co-administration of methylxanthines in cancer therapy used for the enhancement of anti-tumor agent’s activity and serving as candidates for radiosensitization are promising baseline for developing methylxanthines as potential secondary enhancers for future clinical trial.