False-positive results in cryptococcal latex agglutination testing can be caused by

False-positive results in cryptococcal latex agglutination testing can be caused by

• A. cross-reactivity with bacterial antigens.
• B. presence of rheumatoid factor in the specimen.
• C. sample hemolysis.
• D. low sample volume.

Answer: (B)

In cryptococcal latex agglutination testing, the result depends on specific antigen–antibody interactions, but non-specific agglutination can occur if substances in the sample bridge the latex particles. Rheumatoid factor is an IgM autoantibody that binds to the Fc region of IgG, which can link the latex particles together even without cryptococcal antigen present. This non-specific bridging creates a positive signal, leading to a false-positive result. Cross-reactivity with bacterial antigens isn’t a classic, reliable cause of false positives in this assay. Hemolysis or other specimen issues can interfere with test performance and may cause invalid or misleading results, but they’re not typical sources of false positives. Low sample volume tends to reduce sensitivity and increase false negatives rather than produce a false-positive outcome.

In cryptococcal latex agglutination testing, the result depends on specific antigen–antibody interactions, but non-specific agglutination can occur if substances in the sample bridge the latex particles. Rheumatoid factor is an IgM autoantibody that binds to the Fc region of IgG, which can link the latex particles together even without cryptococcal antigen present. This non-specific bridging creates a positive signal, leading to a false-positive result.

Cross-reactivity with bacterial antigens isn’t a classic, reliable cause of false positives in this assay. Hemolysis or other specimen issues can interfere with test performance and may cause invalid or misleading results, but they’re not typical sources of false positives. Low sample volume tends to reduce sensitivity and increase false negatives rather than produce a false-positive outcome.