Therefore, to evaluate whether IL-6 affects Brucella intracellular replication, we infected wild-type (C57BL/6) and IL-6 KO macrophages with a 100:1 multiplicity of infection (MOI) and quantified the number of B. abortus colony forming unit (CFU) in vitro 3 h after infection until 72 h post-infection. This evidence concerns the gene IL6 and infection.