Volume 53, Issue 2
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



Antigen-specific cellular immunity in paracoccidioidomycosis (PCM) has been poorly studied due to lack of standard in vitro lymphocyte proliferation assays. To standardize such an assay, we studied T and B cell responses to a cell wall extract (PbAg) in healthy subjects sensitized to either [Pb(+)Hc(-)] or to [Hc(+)Pb(-)], and in nonsensitized persons. All subjects showed, as expected, a vigorous proliferative response to a control fungal antigen obtained from . Lymphocytes from Pb(+)Hc(-) donors, but not from Pb(-)Hc(-) donors, reacted to PbAg by proliferating in a dose-dependent manner with a maximum reaction after 6–9 days, suggesting a secondary specific immune response. Most activated cells were CD4+ lymphocytes. However, Hc(+)Pb(-) donors' cells reacted with PbAg. Cross-reactivity with was not unexpected, since both fungi, but not , share cell wall immunogenic compounds. An enzyme-linked immunosorbent assay to detect human immunoglobulins (Ig) demonstrated that B cells from Pb(+)Hc(-) donors, but not from Pb(-)Hc(-) ones, reacted with PbAg by secreting high levels of IgG and IgM in 12-day culture supernatants. This secretion was possibly mediated by PbAg-activated CD4+ cells. We believe that analysis of T and B lymphocyte responses to PbAg will be useful in the investigation of the infection-associated immune impairment seen in some PCM patients.


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