U937 cells lacking either TLR3 or TLR4 showed impaired production of IL-6 upon infection with two other strains belonging to L. pneumophila serogroup-1 (S8A Fig) as well as during infection with three other strains representing L. pneumophila serogroups 7, 13, and 14 (S8B Fig). The gene discussed is TLR4; the disease is infection.