Lymphocyte mechanical response triggered by cross-linking surface receptors.

Area of Science:

• Immunology
• Cell Biology
• Biophysics

Background:

• Lymphocyte capping and anchorage modulation involve cell surface protein cross-linking and the cytoskeleton.
• These processes are initiated by cross-linking cell surface proteins, such as surface immunoglobulin (sIg).

Purpose of the Study:

• To measure changes in lymphocyte deformability upon cross-linking cell surface proteins.
• To investigate the role of the cytoskeleton in lymphocyte capping and anchorage modulation.

Main Methods:

• Utilized a recently developed method to measure changes in lymphocyte deformability.
• Quantified cellular stiffness as the rate of force increase with compression.
• Investigated the effects of cross-linking agents (antibodies, Concanavalin A) and their non-cross-linking counterparts.

Main Results:

• Cross-linking surface immunoglobulin (sIg) or Concanavalin A (Con A) receptors significantly increased lymphocyte stiffness.
• Stiffness increased from approximately 0.15 mdyn/micron in untreated cells to 0.6 mdyn/micron (anti-sIg) or 0.4 mdyn/micron (Con A).
• Increased stiffness was reversible with cytochalasin D and colchicine, and dependent on cross-linking.

Conclusions:

• Lymphocyte capping and anchorage modulation involve cytoskeletal changes that increase viscoelastic resistance to deformation.
• Cellular deformability measurements can characterize cytoskeletal functional changes triggered by cell surface signals.
• Similar stiffness increases were observed under hypertonic conditions, azide treatment, and with calcium ionophores.