Elevated adaptive immune responses are associated with latent infections of wuchereria bancrofti
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Date
2012-04
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PLOS
Abstract
In order to guarantee the fulfillment of their complex lifecycle, adult filarial nematodes release millions of microfilariae (MF),
which are taken up by mosquito vectors. The current strategy to eliminate lymphatic filariasis as a public health problem
focuses upon interrupting this transmission through annual mass drug administration (MDA). It remains unclear however,
how many rounds of MDA are required to achieve low enough levels of MF to cease transmission. Interestingly, with the
development of further diagnostic tools a relatively neglected cohort of asymptomatic (non-lymphedema) amicrofilaremic
(latent) individuals has become apparent. Indeed, epidemiological studies have suggested that there are equal numbers of
patent (MF+) and latent individuals. Since the latter represent a roadblock for transmission, we studied differences in
immune responses of infected asymptomatic male individuals (n = 159) presenting either patent (n = 92 MF+) or latent
(n = 67 MF2) manifestations of Wuchereria bancrofti. These individuals were selected on the basis of MF, circulating filarial
antigen in plasma and detectable worm nests. Immunological profiles of either Th1/Th17, Th2, regulatory or innate
responses were determined after stimulation of freshly isolated PBMCs with either filarial-specific extract or bystander
stimuli. In addition, levels of total and filarial-specific antibodies, both IgG subclasses and IgE, were ascertained from plasma.
Results from these individuals were compared with those from 22 healthy volunteers from the same endemic area.
Interestingly, we observed that in contrast to MF+ patients, latent infected individuals had lower numbers of worm nests
and increased adaptive immune responses including antigen-specific IL-5. These data highlight the immunosuppressive
status of MF+ individuals, regardless of age or clinical hydrocele and reveal immunological profiles associated with latency
and immune-mediated suppression of parasite transmission.
Description
Article published in PLOS, April 2012 | Volume 6 | Issue 4 | e1611.Also available at www.plosntd.org
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PLOS, April 2012 | Volume 6 | Issue 4 | e1611
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