Comparison of the PREMIER cryptococcal antigen enzyme immunoassay and the latex agglutination assay for detection of cryptococcal antigens.

A new enzyme immunoassay (EIA), PREMIER Cryptococcal Antigen, was compared with latex agglutination (LA) for the detection and quantitation of circulating capsular polysaccharide antigen from Cryptococcus neoformans. The clinical evaluation of PREMIER EIA as a screening assay, including 475 specimens with 120 LA and EIA positives, resulted in 99% sensitivity and 97% specificity. The clinical specimens included sera and cerebrospinal fluids as well as 10 rheumatoid factor-positive and 20 anti-nuclear antibody-positive serum samples. This monoclonal antibody-based assay detects serotypes A to D at 0.63, 0.63, 7.8, and 62 ng/ml, respectively. With three different known positive specimens, the assay was found to yield coefficients of variation of 2 to 12% for intra- and interassay comparisons of precision and reproducibility. The primary use for semiquantitative values derived with the LA or EIA is to follow the course of disease and monitor drug therapies. The present data suggest that the PREMIER EIA will be a valuable method for this purpose. We conclude that the PREMIER Cryptococcal Antigen EIA provides a rapid, convenient, and reliable antigen detection method for screening and semiquantitative determination of antigen levels.