MONOCLONAL POLYCLONAL ANTIBODIES AND PRONASE IN DETECTION OF CRYPTOCOCCAL ANTIGEN IN SERUM AND CEREBROSPINAL-FLUID/

The advent of Aquired Immunodeficiency Syndrome (AIDS) has increased t he morbility and mortality due to Cryptococcus neoformans. The diagnos is of cryptococcal infection is generally based on microscopic visuali zation and/or culture of clinical specimens, histopathologic examinati on and antigen detection. The latex particle agglutination (LPA) for d etection of the C. neoformans capsular polysaccharide is a rapid, easy and sensitive method for the diagnosis of cryptococcal infection. New improved detection tests claimed to have increased the. specificity. In this study, we retrospectively reviewed 780 sera and cerebrospinal fluid (CSF) samples processed for detection of cryptococcal antigen. T wenty eight frozen samples (10 CSF and 18 sera) were recovered with po sitive results of cryptococcal antigen (low or medium titers, < 1:256) . These samples were tested with four LPA-based diagnostic test with p oly- or monoclonal antibody and with or without pronase. The results o btained show that most of these false positive LPA tests can be elimin ated by a previous pronase treatment, thus increasing the specificity of the test. This potential advantage may be balanced by the decrease in susceptibility, as a result of the lower titers obtained. The absen ce of a reliable correlation between antigen titers obtained by the di fferent kits used in this work indicates that these values should be t aken cautiously, particularly in patients where such titers are used t o follow the response to antifungal therapy.