Dendritic cells (DCs) can take up an array of different
antigens, including microorganisms which they can process and present more effectively than any other antigen presenting cell. However, whether the interaction between the human DC and Mycobacterium tuberculosis represents a defense mechanism by the invaded host, or helping the invader to evade the defense mechanism of the host is still not clearly understood.
FINDINGS: To analyze the interactions between M.
tuberculosis and immune cells, human peripheral blood monocyte-derived immature DCs were infected with M.
tuberculosis H37Rv wild type strain and flow cytometry was used to analyse cell surface expression markers. The ability of the M.
tuberculosis infected DC to induce T cell proliferation using 5 and
6-carboxyfluorescein diacetate succinimidyl
ester (
CFSE) dilution technique was also investigated. DCs were found to internalize the mycobacteria and show dose dependent
infection and
necrosis with different multiplicity of
infection. Flow cytometry analysis of cell surface expression markers CD40, CD54, CD80, CD83, CD86 and
HLA DR in infected DC revealed significant (p < 0.05) up regulation following
infection with M.
tuberculosis in comparison to immature DC with no stimulation.
Lipopolysaccharide (LPS) from Salmonella abortus equi, a known DC maturation agent, was used as a positive control and showed a comparable up regulation of cell surface markers as observed with M.
tuberculosis infected DC. It was revealed that the M.
tuberculosis infected DC induced T cell proliferation.
CONCLUSION: