Among all these genes, 7 of them (CXCL1, IL-6, IL-8, OAS2, STAT1, IFIH1 and SOD2) were already identified in our previous study as belonging to a common core of up-regulated genes stimulated in fibroblasts by different strains of the same species B. burgdorferi ss (strain N40 isolated from tick, strains Pbre and 1408 isolated from patients affected by EM or ACA respectively). Here, IL6 is linked to erythema multiforme.