Serine esterase in cytolytic T lymphocytes

Area of Science:

• Immunology
• Cell Biology

Background:

• Cytotoxic T lymphocytes (Tc cells) and natural killer cells contain cytoplasmic granules with perforin, crucial for target cell lysis.
• Antigen-specific lysis, previously attributed solely to Tc cells, is also observed in T-helper killer (Th/c) cells.

Purpose of the Study:

• To investigate the role of a novel serine esterase in T cell-mediated cytotoxicity.
• To characterize the properties and localization of this serine esterase in murine T cells.

Main Methods:

• Biochemical analysis of serine esterase activity and properties.
• Density gradient centrifugation to assess enzyme sedimentation with perforin.
• Immunological assays using antiserum against Tc-cell serine esterase.

Main Results:

• A novel serine esterase was found at elevated levels in cytolytic Tc and Th/c cell lines, but not in non-cytolytic T-helper cells.
• The enzyme is a membrane-associated, disulphide-linked dimer with trypsin-like activity, co-sedimenting with perforin.
• The serine esterase is secreted by Tc cells during target cell attack and is present in Th/c cells.

Conclusions:

• The serine esterase is implicated in the cytolytic activity of Tc cells and potentially Th/c cells.
• A shared cytolytic mechanism involving this serine esterase may exist across different effector T cell types.