Thus, a lipoteichoic acid and lipoprotein containing cell wall preparation (LTA), activating TLR2, or a Salmonella minnesota LPS preparation, activating TLR4, were used for alternative pre-treatment of THP-1 cells to test whether TLR activation alone is able to alter the response of macrophages to an infection with L. pneumophila. This evidence concerns the gene TLR2 and infection.