A novel receptor involved in T-cell activation

Area of Science:

• Immunology
• Molecular Biology
• Cellular Biology

Background:

• T-cell activation requires T-cell receptor and co-stimulatory signals.
• CD28 is a major co-stimulatory molecule, but not essential for all T-cell responses.
• The existence of alternative T-cell co-stimulatory pathways is suggested.

Purpose of the Study:

• To identify and characterize novel molecules involved in T-cell co-stimulation.
• To investigate the role of a newly identified glycoprotein, SLAM, in T-cell activation.
• To elucidate the signaling pathway of SLAM in T-cell responses.

Main Methods:

• Identification and characterization of a novel glycoprotein (SLAM).
• Analysis of SLAM expression on various T-cell populations.
• Investigating the effect of SLAM engagement on T-cell proliferation and cytokine production.
• Assessing the role of CD28 in SLAM-mediated T-cell activation.

Main Results:

• SLAM, a novel M(r) 70K glycoprotein, is identified and belongs to the immunoglobulin superfamily.
• SLAM is expressed on memory T cells, T-cell clones, thymocytes, and B cells, and induced on naive T cells upon activation.
• SLAM engagement enhances antigen-specific T-cell proliferation and interferon-gamma (IFN-gamma) production in a CD28-independent manner.
• SLAM induces a Th0/Th1 cytokine profile, upregulating IFN-gamma even in Th2 clones.

Conclusions:

• SLAM is a novel T-cell receptor involved in T-cell stimulation.
• SLAM engagement potentiates T-cell expansion and IFN-gamma production independently of CD28.
• SLAM represents a new pathway for modulating T-cell immune responses.