Lysis of human macrophages by cytolytic CD4+ T cells fails to affect survival of intracellular Mycobacterium bovis-bacille Calmette-Guérin (BCG).
Human CD4+, mycobacteria-specific, cytolytic T cell clones were used to lyse BCG-infected macrophages, and the effect on the subsequent growth and viability of the organisms was examined. The survival of released bacteria following cell lysis was assessed by both 3H-uridine labelling and colony-forming unit (CFU) estimation. The results indicate that even when effective antigen-specific or lectin-mediated cytolysis of the infected macrophages was achieved, there was no evidence for a direct mycobactericidal effect on the intracellular bacteria. This remained the case even if the period of co-culture of T cells and macrophages was extended up to 48 h. Pretreatment of the macrophages with interferon-gamma (IFN-gamma) was not able to act together with T cell-mediated lysis to produce inhibition of mycobacterial growth.
Fazal
N
N
Department of Immunology, University of Birmingham, UK.
Lammas
D A
DA
Rahelu
M
M
Pithie
A D
AD
Gaston
J S
JS
Kumararatne
D S
DS
D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002478:Cells, Cultured; D002999:Clone Cells; D003602:Cytotoxicity, Immunologic; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000276:immunology*; D009163:Mycobacterium bovis / Q000254:growth & development / Q000276:immunology*