Different trypanozoan species possess CD8 dependent lymphocyte triggering factor-like activity

Area of Science:

• Immunology
• Parasitology
• Molecular Biology

Background:

• Trypanosoma brucei brucei releases trypanosome-derived lymphocyte triggering factor (TLTF).
• TLTF stimulates CD8+ T cells to produce cytokines and proliferate.
• The presence and activity of TLTF-like molecules in other Trypanosoma species are not fully understood.

Purpose of the Study:

• To investigate the presence and activity of TLTF or similar molecules in Trypanosoma evansi, T.b. gambiense, and T.b. rhodesiense.
• To determine if these molecules also trigger CD8+ cell responses.
• To compare the immunological activity across different Trypanosoma species.

Main Methods:

• Homogenates from T. evansi, T.b. gambiense, and T.b. rhodesiense were used to stimulate mouse/rat mononuclear cells (MNC).
• Interferon gamma (IFN-gamma) production and cell proliferation were measured.
• Responses were assessed in CD8+ vs. CD8- mice and human CD8+ vs. CD4+ enriched peripheral blood mononuclear cells (PBL).
• T.b. brucei-directed anti-TLTF monoclonal antibodies (mAbs) were used to probe for TLTF-like molecules.

Main Results:

• Homogenates from all tested Trypanosoma species induced IFN-gamma production and proliferation in MNC.
• These responses were CD8-dependent, as confirmed by antibody blocking and experiments in CD8+ vs. CD8- mice and human PBL.
• Anti-TLTF mAbs affected the lymphocyte-triggering activity of T.b. gambiense and T.b. rhodesiense, but not T. evansi.
• T. evansi, T.b. rhodesiense, and T.b. gambiense share TLTF antibody-binding epitopes.

Conclusions:

• T. evansi, T.b. rhodesiense, and T.b. gambiense possess molecules that CD8 dependently trigger lymphocytes, similar to T.b. brucei.
• These related Trypanosoma species share epitopes recognized by anti-TLTF antibodies.
• The findings indicate a conserved mechanism of immune modulation across these parasitic species.