Levels of specific antigen (gp43), specific antibodies, and antigen-antibody complexes in saliva and serum of paracoccidioidomycosis patients

Abstract

The present study analyses human immunoglobulin G (IgG) antibodies directed against the Paracoccidioides brasiliensis exoantigen, gp43, as well as the presence of gp43-IgG immune complexes (ICs) in 31 samples of saliva and serum from 19 patients with paracoccidioidomycosis (PCM) and 12 normal donors. Additional analysis of secretory IgA (sIgA) was performed on the same saliva samples. Consistent with previous findings, a significant increased specific IgG level was observed in PCM patients' saliva and serum (P < 0.05). The analysis of serum gp43 and gp43-IgG IC demonstrated a higher level in patients with PCM (P < 0.05); however, this difference was not statistically significant with regard to gp43 and gp43-IgG in saliva when compared to the healthy donors. A high level of sIgA in saliva of PCM patients compared to that of normal donors was also observed (P < 0.05). Patients exhibiting low levels of serum IgG but with high titres of IC were observed, thus strengthening the idea of the necessity to use more than one marker for diagnosis and treatment monitoring of PCM. This is the first report of sIgA in PCM patients' saliva and may be indicative of a protective role in neutralizing antigens on mucosal surfaces.

Human serum antibody reactivity towards Paracoccidioides brasiliensis antigens treated with sodium metaperiodate

“…It is very well known that chronic inflammation of the mucosa stimulates production of IgA antibodies 1 9 10 . In addition, the secretory IgA in saliva from PCM patients may be indicative that it has a protective role regarding antigen neutralization on mucosal surfaces 15 . Previous studies showed that IgG1 antibodies were present, frequently at high levels, in subacute and chronic PCM patients 1 11 .…”

High molecular mass fraction in clinical isolates of Paracoccidioides brasiliensis

“…The gp43 glycoprotein, one of the most important immunodominant antigens of P. brasiliensis, has been extensively investigated, particularly in relation to diagnosis [20][21][22] . Gp43 has been detected at higher levels in PCM patient sera as circulating antigens 22 and in CSF and bronchoalveolar lavage (BAL) fluid samples from PCM patients 11 .…”

“…The gp43 glycoprotein, one of the most important immunodominant antigens of P. brasiliensis, has been extensively investigated, particularly in relation to diagnosis [20][21][22] . Gp43 has been detected at higher levels in PCM patient sera as circulating antigens 22 and in CSF and bronchoalveolar lavage (BAL) fluid samples from PCM patients 11 . However, recently the existence of a P. brasiliensis isolate presenting differences in this major antigen coding gene gp43 23,24 has been demonstrated and speculation of the possibility of a new species in the genus Paracoccidioides has been noted.…”

“…Considering the proportion and as a soluble antigen present in CFA, we speculate that its presence may also be observed as a soluble antigen during infection, similar to other antigens, such as gp43 or gp70, present in CFA and in the serum 11,13,22,26 , with the potential for diagnosis and follow-up of the PCM patients. Thus, the hMM fraction is also important when considering the distinct isotypic humoral immune response to hMM antigens with ~336kDa observed in the acute and chronic forms of the PCM disease, which suggest that it has potential as a new biomarker for differentiating these two clinical forms 16 .…”

“…The analysis was performed using polAb or mAb to the hMM fraction as a secondary antibody and the results showed a stronger correlation between hMM fraction levels obtained using pAb or mAb anti-hMM. cELISA with specific polAb and mAb was used in previous studies by our group to determine circulating soluble gp43 levels in PCM 22 and determining plasmatic hMM fraction levels in PCM patients by cELISA will be the object of future investigations.…”