Monitoring gp43 antigenemia in Paracoccidioidomycosis patients during therapy

Abstract

Paracoccidioidomycosis (PCM) is a systemic fungal disease that is particularly important among individuals living and working in rural areas of endemicity in Latin America. Detection of anti-Paracoccidioides brasiliensis antibodies is of limited value due to false-negative results. Detection of P. brasiliensis-gp43 circulating antigen is a practical approach for a specific diagnosis of the disease. In a previous study we described an inhibition enzyme-linked immunosorbent assay able to detect the 43-kDa P. brasiliensis antigen in sera of 100% of patients with the acute form of PCM and in 95.31 and 100% of patients with the chronic multifocal and unifocal forms of PCM. To investigate its potential application for the follow-up of PCM patients during treatment, antigen levels were monitored at regular intervals for up 8 to 12 months in serum samples from 23 patients. The results showed that treatment with itraconazole resulted in decreasing levels of circulating gp43 that were correlated with the reduction of anti-gp43 antibodies. It was also observed that by the end of 12 months of treatment gp43 levels were <5 microg/ml in all patients.

FIG. 1.

Media of circulating antigen concentrations in sera from patients with PCM at the time of diagnosis and during treatment. Error bars indicate the standard deviations.

FIG. 2.

Serologic follow-up curves of 23 PCM patients during treatment. Left panels show gp43 antigen concentrations; right panels show anti-gp43 antibody titers.

FIG. 3.

Correlation between the levels of antigenemia due to gp43 and anti-gp43 antibody titers at the time of diagnosis (A) and at the end of treatment (B). NR, nonreactor; NDS, not diluted sera.