A human T lymphocyte differentiation marker defined by monoclonal antibodies that block E-rosette formation

Area of Science:

• Immunology
• Cell Biology
• Surface Antigen Research

Background:

• T lymphocytes play a critical role in immune responses.
• Identifying specific cell surface markers aids in understanding T cell subsets and functions.
• The interaction between T cells and sheep erythrocytes (SRBC) is a model for studying T cell recognition.

Purpose of the Study:

• To define a new human T cell surface antigen, designated Leu-5.
• To characterize the expression pattern and molecular properties of the Leu-5 antigen.
• To investigate the potential role of Leu-5 in T lymphocyte function, particularly SRBC binding.

Main Methods:

• Monoclonal antibody production and characterization.
• Quantitative immunofluorescence analysis using Fluorescence-Activated Cell Sorting (FACS).
• Immunoprecipitation to determine antigen molecular weight and structure.

Main Results:

• A novel T cell surface antigen, Leu-5, was identified using monoclonal antibodies.
• Leu-5 is a 40-50 kDa single polypeptide chain found on thymocytes, peripheral T cells, and some null cells, but not B cells.
• Leu-5 density decreases with T cell maturation, correlating with SRBC binding affinity.

Conclusions:

• Leu-5 is a human T cell differentiation antigen.
• The expression pattern of Leu-5 suggests its involvement in T cell recognition of SRBC.
• Leu-5 may be identical to or closely associated with the SRBC receptor on human T lymphocytes.