title: Elevated adaptive immune responses are associated with latent infections of Wuchereria bancrofti.
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 MF(-)) 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.
authors.affiliation: Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Arndts
authors.forename: Susanne
authors.initials: S
authors.lastname: Deininger
authors.forename: Sabine
authors.initials: S
authors.lastname: Specht
authors.forename: Ute
authors.initials: U
authors.lastname: Klarmann
authors.forename: Sabine
authors.initials: S
authors.lastname: Mand
authors.forename: Tomabu
authors.initials: T
authors.lastname: Adjobimey
authors.forename: Alexander Y
authors.initials: AY
authors.lastname: Debrah
authors.forename: Linda
authors.initials: L
authors.lastname: Batsa
authors.forename: Alexander
authors.initials: A
authors.lastname: Kwarteng
authors.forename: Christian
authors.initials: C
authors.lastname: Epp
authors.forename: Mark
authors.initials: M
authors.lastname: Taylor
authors.forename: Ohene
authors.initials: O
authors.lastname: Adjei
authors.forename: Laura E
authors.initials: LE
authors.lastname: Layland
authors.forename: Achim
authors.initials: A
authors.lastname: Hoerauf
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D058345:Asymptomatic Infections; D015331:Cohort Studies; D004605:Elephantiasis, Filarial / Q000276:immunology* / Q000473:pathology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D008875:Middle Aged; D013601:T-Lymphocytes / Q000276:immunology; D014958:Wuchereria bancrofti / Q000276:immunology* / Q000472:pathogenicity*; D055815:Young Adult
chemical_list: D000909:Antibodies, Helminth; D007074:Immunoglobulin G; D007073:Immunoglobulin E