The use of nanoparticles for new therapeutic and diagnostics options represents a new risk for individuals exposed to such compounds. The myelomonocytic cell line THP-1 could be a useful alternative to human peripheral blood mononuclear cells (PBMC) to test for effects of drugs and compounds. Stimulation degree of cells can be monitored by measurement of neopterin and/or the kynurenine to tryptophan ratio. The method is robust and reproducible in the range of 0.1-1.0 microg/ml of LPS. However, compared to the PBMC assay it will not reveal any effect on the T-cell interaction.