Role of Signaling Lymphocytic Activation Molecule in Intracellular Bacterial Infection

GARCÍA V; QUIROGA MF; OCHOA M; SIELING P; MODLIN R

Seattle, WA, EUA

Congreso; Immunology 2000; 2000

AAI

Signaling lymphocytic activation molecule (SLAM) is a T cell costimulatory molecule rapidly induced on naïve T cells after activation.  Ligation of human SLAM induces CD28-independent proliferation of human T cells and enhances Ag-specific proliferation and IFN-g production by Th1, as well as by Th2 clones.  We investigated the role of SLAM in leprosy, a disease characterized by polar cytokine responses.  We found a significant up-regulation of SLAM expression on CD3+ T cells from leprosy patients compared to healthy donors.  Furthermore, the effect of specific antigen-stimulation on SLAM expression was also investigated.  CD3+ T cells from tuberculoid leprosy patients showed a significant increase in the level of SLAM expression after stimulation with Mycobacterium leprae, while the expression of SLAM on CD3+T cells from lepromatous patients was not modified by antigen-stimulation.  SLAM mRNA and protein were more strongly expressed in immunologically resistant tuberculoid patients than in unresponsive and susceptible lepromatous patients.  In addition, engagement of SLAM up-regulated IFN-g production from tuberculoid patients and slightly increased the levels of IFN-g in lepromatous patients.  These findings indicate a role for SLAM in cell-mediated immunity against intracellular pathogens.