Activation of human Vgamma9Vdelta2 T cells by a Brucella suis non-peptidic fraction impairs bacterial intracellular multiplication in monocytic infected cells.

Human gamma delta T cells are considered to play an important role in the early response to infection with intracellular pathogens. Evidence has been presented that the percentage of gamma delta T cells with Vgamma9Vdelta2 phenotype is dramatically increased in the peripheral blood of patients with acute brucellosis. This specific gd T-cell subpopulation is known to be activated by small non-peptidic molecules that can either be produced by the pathogen itself or released from damaged cells after infection. In the present work we provide evidence that Vgamma9Vdelta2 T lymphocytes from peripheral blood mononuclear cells of healthy donors can be specifically activated by non-peptidic low-molecular-weight compound(s) from Brucella suis lysate. Moreover, we show that Vgamma9Vdelta2 T cells activated by this B. suis fraction produce tumour necrosis factor-alpha and interferon-gamma, which reduce bacterial multiplication inside infected cells.