Human T lymphocytes and monocytes bear the same Leu-3(T4) antigen

Area of Science:

• Immunology
• Molecular Biology
• Virology

Background:

• The Leu-3(T4) antigen is crucial for T lymphocyte function and recognition.
• Understanding its cellular distribution and structure is vital for immunological research.
• The human T-lymphotropic virus type III (HTLV-III) targets T lymphocytes, making T4 antigen research significant.

Purpose of the Study:

• To analyze the cellular distribution, biosynthesis, and structure of the human T lymphocyte antigen Leu-3(T4).
• To compare Leu-3(T4) antigen expression and characteristics in different cell lines, including T lymphocytes and monocyte/macrophages.
• To investigate the potential for other cell types to express Leu-3(T4) and be targets for HTLV-III.

Main Methods:

• Enzyme-linked immunosorbent assay (ELISA) to quantify Leu-3(T4) antigen.
• Fluorescence-activated cell sorting (FACS) analysis for cell surface antigen detection.
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to determine molecular weight and structure.

Main Results:

• T-T hybrid cell line 255.88 and monocyte/macrophage cell line U937 were identified as high producers of Leu-3(T4).
• Leu-3(T4) from T lymphocytes and monocytes showed identical molecular weights (55,000 AMW under reducing conditions, 63,000 AMW nonreducing).
• The Leu-3(T4) molecule possesses a high mannose sugar side chain and limited accessible tyrosine residues.

Conclusions:

• Human T lymphocytes and monocytes produce and process similar molecules recognized by the anti-Leu-3(T4) antibody.
• The Leu-3(T4) antigen is structurally characterized, revealing its polypeptide nature and glycosylation.
• Findings suggest that cell types beyond T lymphocytes might be targets for the HTLV-III retrovirus.