Tumor necrosis factor receptor 2 plays a minor role for mycobacterial immunity

Tumor necrosis factor (TNF) signalling via the TNF receptor 1 (TNF-R1) is required for host resistance to mycobacterial infection. The role of TNF-R2 in anti-mycobacterial immunity is not known. Therefore, we compared TNF-R1 and TNF-R2 knockout (KO) mice infected with Mycobacterium bovis BCG (10(7) CFU, i.v.). While the bacterial burden of TNF-R1-deficient mice was significantly increased and the mice succumbed to infection between 4 and 5 weeks, TNF-R2 KO mice were less sensitive, and only 3 of 10 mice died within 12 weeks. Wild-type (WT) mice were resistant to BCG infection. The inability to clear the infection of TNF-R1 KO mice was associated with a reduced delayed-type hypersensitivity (DTH) response to purified protein derivative and severe impairment in forming granulomas with reduced macrophage recruitment and activation, and diminished expression of adhesion molecules. By contrast, TNF-R2 KO mice developed normal DTH response and mature mycobactericidal granulomas as the WT mice. Therefore, anti-mycobacterial immunity is largely dependent on TNF signalling via the TNF-R1, while activation of TNF-R2 plays a minor role.