In the study cited by Silva-Gomes and colleagues, however, Mtb were administered intravenously; since the natural route of infection is via the respiratory system and one role of the granuloma is to prevent dissemination of mycobacteria, there are numerous possible explanations for the lack of difference in Mtb clearance in this model that may conceal an essential role for MCP-1/CCR2 in the granulomatous response to mycobacteria. Here, CCL2 is linked to infection.