In latex agglutination testing, what indicates a positive result?

In latex agglutination testing, what indicates a positive result?

• A. agglutination of antigen covered latex beads (visible clumping)
• B. no signs of agglutination
• C. visible clumping of beads with no antigen
• D. color change without clumping

Answer: (C)

Latex agglutination works when specific antigen–antibody pairs link the coated beads together, forming visible clumps. If the sample contains the matching antibody (or antigen) for what’s on the beads, cross-linking occurs and you see bead clumping—that’s a positive result. If that specific interaction isn’t present, the beads don’t link and remain evenly dispersed, so there’s no clumping. A clump with beads that aren’t carrying the relevant antigen would be non-specific and not a true positive, and a color change without clumping isn’t how a positive readout is determined in this test.

Latex agglutination works when specific antigen–antibody pairs link the coated beads together, forming visible clumps. If the sample contains the matching antibody (or antigen) for what’s on the beads, cross-linking occurs and you see bead clumping—that’s a positive result. If that specific interaction isn’t present, the beads don’t link and remain evenly dispersed, so there’s no clumping. A clump with beads that aren’t carrying the relevant antigen would be non-specific and not a true positive, and a color change without clumping isn’t how a positive readout is determined in this test.