Hypothesis testing immune system

In vitro investigations have attempted to clarify the mechanism of immune activation but so far have provided limited data. Studies testing the hypothesis that implicated tryptophan or EBT can trigger PBMCs to release cytokines have been equivocal, although one study found that EBT activates eosinophils and induces IL-5 production from T cells. Another recent study found that certain lots of L-tryptophan could stimulate PBMCs to release granulocyte-macrophage colony-stimulating factor (GM-CSF) this response, however, was caused by endotoxin contamination and not associated with case lots of tryptophan. The mechanism of immune activation is clearly complex and may be difficult to reproduce with an in vitro assay. Similar difficulties have been encountered in the study of immune system activation in TOS. 

Nearly 100 years ago, Paul Ehrlich has proposed about the existence of certain relationship between tumor formation and host immune system [54,55]. However, this hypothesis has not been tested for a long time due to the limitations of technology in this field of research to test the theory experimentally [55]. 

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