Toxicogenomics: an emerging discipline.

Corresponding Author Email: [email protected] THE aim of th is s tudy was to dete rm ine phenotypic dif ferences w hen BCG in vades m acrophage s . Bacilli prepared from the sam e BCG prim ary seed, but produced in dif ferent culture m edia , w ere analysed w ith respect to th e ability to s tim ulate m acrophages and the susceptibility to tr eatm ent w ith cytokine s and n itr ic ox ide (NO). Tum our necrosis factor (TNF) activity w as assayed by m easuring its cytotox ic activity on L-929 cells, in terleukin-6 (IL-6 ) and in ter fe rong (IFN-g ) w ere assayed by enzym e-linked im m unosorben t assay (ELISA ), w hereas NO leve ls were de tected by Grie ss color im etric r eactions in the culture supernatant of m acrophage s in cubated w ith IFN-g , TNF or NO and subsequently ex posed to eith er BCG-I or BCG-S. We found that BCG-I and BCGS bacilli show ed diffe rent ability to s im ulate pe ritoneal m acrophage s . Sim ilar levels of IL-6 w ere detected in s tim ulated m acrophage s w ith lysate from tw o BCG sam ples . The high est leve ls of TNF and IFN-g w ere observed in m acrophages tr eated w ith BCG-S and BCG-I, re spective ly. Th e h igh est levels of NO w ere obse rved in cultures s tim ulated for 48 h w ith BCG-S. We also found a diffe ren t sus ceptibility of the bacilli to ex ogenous treatm ent w ith IFNg and TNF w hich w ere capable of killin g 60 and 70% of both bacilli, whereas NO w as capable of killing about 98 and 47% of BCG-I and BCG-S, r espectively. The am ount of bacilli proportionally decreased w ith IFNg and TNF, sugge stin g a cytokin e-related cytotox ic effe ct. Moreover, NO also decreased the viable numbe r of bacilli. In terestin gly, NO leve ls of peritoneal m acrophage s w ere s ign ificantly in creased after cytokin e tr eatm ent. Th is indicate s that th e tr eatm ent of m acrophage s w ith cytokine s m arkedly reduced bacilli num ber and presented e ffe cts on NO production . Th e results obtained here em phasize the im portance of adequate s tim ulation for guaran teein g effic ien t killin g of bacilli. In th is particular case, the IFN-g and TNF w ere involved in the activation of m acrophage bacteric idal activity .