Comparative sensitivity: agglutination reactions are generally more sensitive than precipitation for detecting which laboratory target?

Introduction / Context:
Agglutination tests (e.g., latex agglutination, passive hemagglutination) enhance visual readouts by presenting antigens on particles, making very small amounts of antibodies detectable. Knowing which analyte is best detected by agglutination guides test selection in clinical labs.

Given Data / Assumptions:

• Agglutination increases visual signal by particle clumping.
• Precipitation requires higher concentrations and balanced proportions.
• The question asks which target is more sensitively detected by agglutination versus precipitation.

Concept / Approach:
When soluble antigens are coated onto particles, even low-titer antibodies can cross-link multiple particles and form visible clumps. This particle amplification significantly raises sensitivity for antibody detection compared with faint precipitin lines in gels or tubes.

Step-by-Step Solution:

Verification / Alternative check:
Many antibody screens (e.g., anti-CRP latex tests historically, rheumatoid factor assays) use agglutination for improved sensitivity over precipitation methods.

Why Other Options Are Wrong:

• Antigens can also be detected by agglutination, but the classic teaching emphasizes superior detection of antibodies when antigens are particle-bound.
• Complement and immune complexes are not primary targets of simple agglutination kits.
• None of the above: Incorrect, because antibodies are specifically enhanced by agglutination methods.

Common Pitfalls:

• Assuming precipitation and agglutination have equivalent limits of detection.

Final Answer:
Antibodies