Purified lymphocyte function-associated antigen 3 binds to CD2 and mediates T lymphocyte adhesion

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• CD2 is a T lymphocyte glycoprotein involved in cell adhesion and activation.
• Lymphocyte Function-Associated Antigen 3 (LFA-3) is a cell surface glycoprotein.
• Previous data suggested LFA-3 might be the biological ligand for CD2.

Purpose of the Study:

• To purify and functionally characterize LFA-3 from human erythrocytes.
• To confirm LFA-3 as the biological ligand for CD2.
• To demonstrate LFA-3's role in mediating T lymphocyte adhesion.

Main Methods:

• Purification of LFA-3 from human erythrocytes.
• Functional characterization of purified LFA-3 using binding assays with CD2+ cells.
• Inhibition studies using CD2 monoclonal antibodies (mAb).
• Rosetting and aggregation assays with T lymphocytes and T lymphoma cell lines.
• Reconstitution of LFA-3 into planar membranes.

Main Results:

• Purified LFA-3 specifically bound to CD2+ cells, inhibited by CD2 mAb.
• LFA-3 half-saturated CD2 at 1-5 nM, indicating high affinity.
• LFA-3 inhibited T cell rosetting and mediated T cell aggregation.
• Reconstituted LFA-3 facilitated CD2-dependent T lymphoblast adhesion.

Conclusions:

• LFA-3 is confirmed as a ligand for CD2.
• LFA-3 plays a crucial role in mediating T lymphocyte adhesion.
• These findings elucidate a key interaction in T cell-mediated immunity.