Emily Eriksson, Arne Forsgren and Kristian Riesbeck1

Department of Medical Microbiology, Lund University, Malmö University Hospital, Sweden

1Correspondence: Department of Medical Microbiology, Malmö University Hospital, Lund University, SE-205 02 Malmö, Sweden. E-mail: kristian.riesbeck@mikrobiol.mas.lu.se

Fluoroquinolones have immunomodulatory properties and interfere with cytokine production. The aim of this study was to characterize the extent of the superinduced mRNA levels in activated human lymphocytes incubated with ciprofloxacin (5 and 80 µg/ml) using a cytokine gene expression microarray from R&D Systems (Abingdon, UK). Several gene transcripts (n=104) were up-regulated in cells treated with ciprofloxacin at 80 µg/ml, whereas 98 transcripts were down-regulated out of 847 total genes included on the microarray. The increased mRNAs were distributed between major gene programs, including interleukins (36.5%), signal-transduction molecules (13.5%), adhesion molecules (10.6%), tumor necrosis factor and transforming growth factor-ß superfamilies (10.6%), cell-cycle regulators (9.6%), and apoptosis-related molecules (8.7%). To determine the specificity of the microarray, a quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), which contained a panel of 12 different cytokine mRNAs, was used. Eleven out of the 12 gene transcripts were up-regulated in the specific RT-PCR, whereas only eight were found to be increased in the microarray. A microarray from Clontech (Hampshire, UK), containing 588 different genes, was also included. Results obtained with this broad-coverage expression array slightly differed compared with the other microarray. We conclude that the fluoroquinolone ciprofloxacin at high concentrations interferes with several gene programs, which is in accordance with a mammalian stress response. From a technical point of view, a discrepancy may exist between data obtained by different microarrays and more specific methods such as quantitative RT-PCR.