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Clinical and Diagnostic Laboratory Immunology, 09 1995, 569-573, Vol 2, No. 5
OA Martins-Filho, ME Pereira, JF Carvalho, JR Cancado and Z Brener
Sera from patients chronically infected with Trypanosoma cruzi display
antibodies that bind to epitopes of living trypomastigotes, known as lytic
antibodies (LA), and are detected by a complement-mediated lysis test.
Conventional serology antibodies (CSA) are also present in sera from
patients with chronic infections but, in contrast to LA, are unable to
recognize viable trypomastigotes. The presence of LA has been used as an
important element in the criterion of cure in human Chagas' disease. Using
flow cytometry technology, we introduced a new and sensitive immunomethod
for the detection of anti-live trypomastigote membrane-bound antibodies. On
the basis of serological tests (LA and CSA detection) and parasitological
assays such as hemoculture (HE), patients were classified into the
following groups: chronically infected untreated patients (NT) and treated
not-cured patients (TNC), with positive HE and both LA and CSA in their
sera; "dissociated" HE- negative patients (DIS), in whom LA was not
detected whereas CSA were present; a group of cured HE-negative patients
(CUR), who were both LA and CSA negative; and, as control, a group of
non-chagasic individuals (NC). Sera from these patients were assayed by
incubation with live bloodstream trypomastigotes, which were subsequently
exposed to fluorescein isothiocyanate-conjugated anti-human immunoglobulin
G. The parasites were then fixed, run in the cytometer, and identified on
basis of their size and granularity gain adjustments. On the basis of
experience with the complement-mediated lysis test, a level of 20% of
parasites being fluorescein isothiocyanate fluorescence positive was used
as a cutoff between effective and ineffective treatments.(ABSTRACT
TRUNCATED AT 250 WORDS)
Copyright © 1995 by the American Society for Microbiology. All rights reserved.
Flow cytometry, a new approach to detect anti-live trypomastigote antibodies and monitor the efficacy of specific treatment in human Chagas' disease
Centro de Pesquisas Rene Rachou, FIOCRUZ, Belo Horizonte, MG, Brazil.
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