A technician runs an indirect latex agglutination assay and obtains no visible clumping in a patient sample, while the positive control clumps normally. Which explanation is most consistent with a false‑negative caused by the prozone phenomenon?

• A. Low ionic strength of the patient’s sample causes immediate precipitation of proteins unrelated to antigen–antibody interactions, which masks any agglutination reaction.
• B. Excess antibody in the patient sample saturates antigens on particles preventing lattice formation, producing a false‑negative despite controls working properly.
• C. The beads in the test are the wrong size and their large diameter physically prevents antibody binding to any antigen present in the sample, thereby blocking agglutination.
• D. Contamination of the patient sample with an irrelevant microbe caused cross‑agglutination and therefore prevented detection of the target antigen, producing a false‑negative result.

Answer: (B)