In nephelometry, which solution would not enhance antigen-antibody complex formation?

In nephelometry, which solution would not enhance antigen-antibody complex formation?

• A. Polyethylene glycol
• B. High-ionic-strength saline solution
• C. Normal saline
• D. Complement

Answer: (C)

In nephelometry you want larger, well-formed antigen–antibody complexes because they scatter more light. Agents that promote aggregation or cross-linking boost the signal. Polyethylene glycol pulls antibodies and antigens together by excluding solvent, increasing lattice formation. A high-ionic-strength saline solution reduces electrostatic repulsion between molecules, helping them bind and form complexes. Complement can also promote cross-linking of complexes, enhancing scattering. Normal saline, at physiological ionic strength, doesn’t promote precipitation or extra cross-linking, so it wouldn’t enhance complex formation beyond the baseline.

In nephelometry you want larger, well-formed antigen–antibody complexes because they scatter more light. Agents that promote aggregation or cross-linking boost the signal. Polyethylene glycol pulls antibodies and antigens together by excluding solvent, increasing lattice formation. A high-ionic-strength saline solution reduces electrostatic repulsion between molecules, helping them bind and form complexes. Complement can also promote cross-linking of complexes, enhancing scattering. Normal saline, at physiological ionic strength, doesn’t promote precipitation or extra cross-linking, so it wouldn’t enhance complex formation beyond the baseline.