Insulin binding to cultured B- and T-lymphocytes

Area of Science:

• Immunology
• Endocrinology
• Cell Biology

Background:

• Insulin receptors are present on activated T-lymphocytes but not resting ones.
• The expression of insulin receptors on B-lymphocytes and their role in cell transformation is not well understood.

Purpose of the Study:

• To investigate and compare insulin binding to various T- and B-cell lines.
• To determine if transformed B-lymphocytes express insulin receptors and characterize their binding properties.

Main Methods:

• Utilized [125I]insulin tracer to quantify insulin binding to T- and B-cell lines.
• Compared insulin binding across radiation- and virus-transformed cell lines.
• Characterized binding affinity, specificity, and receptor number per cell.

Main Results:

• T-cell lines and a mouse B-cell line showed minimal insulin binding (<3%).
• A specific leukemic B-cell line (1605 L) demonstrated high insulin binding (40%).
• This B-cell line exhibited high-affinity binding (1.9 nM-1), characteristic insulin receptor specificity, and 16,600 receptors/cell.

Conclusions:

• Transformed B-lymphocytes can express substantial levels of insulin receptors.
• The high expression in the 1605 L cell line may be linked to Epstein-Barr virus co-expression.
• This suggests a potential role for insulin signaling in B-cell transformation and lymphomagenesis.