Step conductance increases in bilayer membranes induced by antibody-antigen-complement action

Area of Science:

• Biophysics
• Immunology
• Membrane Biology

Background:

• Lipid bilayer membranes are crucial biological structures.
• The complement system is a key part of the immune response.
• Understanding membrane-protein interactions is vital in immunology.

Purpose of the Study:

• To investigate the effect of antigen-antibody complexes and complement on lipid bilayer membrane electrical conductance.
• To determine the mechanism of membrane alteration induced by these components.

Main Methods:

• Electrical conductance measurements of lipid bilayer membranes.
• Controlled addition of antigen (bovine serum), antibody (rabbit anti-bovine serum), and complement.
• Analysis of conductivity changes to infer membrane pore formation.

Main Results:

• A sharp increase in electrical conductance was observed.
• Step increases in conductivity indicated the formation of discrete pores.
• The apparent size of these pores was estimated to be around 2.2 nm.

Conclusions:

• Complement activation, triggered by antigen-antibody complexes, significantly alters lipid bilayer membrane properties.
• The formation of small pores (approx. 2.2 nm) is likely responsible for the observed increase in conductance.
• Complement-mediated attack or lysis of the lipid bilayer is the probable mechanism.