Hodgkin's cell lectin, a lymphocyte adhesion molecule and mitogen

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Hodgkin's disease (HD) cells express a novel galactose/N-acetylgalactosamine specific lectin activity (HD lectin) mediating lymphocyte adhesion.
• Both membrane-bound and secreted HD lectin activities are implicated in lymphocyte activation.
• Intercellular adhesion molecule-1 (ICAM-1) serves as an alternative binding site for peripheral blood lymphocytes (PBLs).

Purpose of the Study:

• To investigate the role of HD lectin and ICAM-1 in lymphocyte activation by HD cells.
• To identify the secreted factors from HD cells that contribute to lymphocyte activation.
• To explore the potential physiological relevance of HD lectin functions in HD-related immunodeficiency.

Main Methods:

• Utilized cultured HD cell lines (L428, L540) and their variants.
• Employed monoclonal antibodies (mAbs) against various cell surface molecules (CD2, CD3, CD4, CD8, CD11a, CD11b, CD11c) to block specific interactions.
• Analyzed lymphocyte activation, DNA synthesis, and conditioned media from HD cells.

Main Results:

• HD lectin, both membrane-bound and secreted, actively participates in activating agglutinated lymphocytes.
• ICAM-1 provides an alternative binding site for PBLs but is not essential for HD lectin-mediated stimulation.
• A soluble form of HD lectin, sharing properties with the membrane-bound form, was identified as a key factor in lymphocyte activation.
• HD cell membranes and conditioned media could stimulate resting lymphocytes, inducing DNA synthesis.

Conclusions:

• The HD lectin functions as both a lymphocyte adhesion molecule and a mitogen.
• Lymphocyte activation by HD cells is dependent on secreted factors, including the soluble HD lectin.
• The identified functions of HD lectin suggest a potential role in the severe immunodeficiencies observed in Hodgkin's disease patients.