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Infection and Immunity, December 2001, p. 7453-7460, Vol. 69, No. 12
Centro de Pesquisas Gonçalo Moniz
(FIOCRUZ),1 Instituto de Ciências
da Saúde da Universidade Federal da
Bahia,3 and Faculdade de Medicina da
Universidade Federal da Bahia,4 Salvador, Bahia,
and Núcleo de Medicina Tropical, Universidade Federal do
Ceará, Fortaleza, Ceará,2 Brazil
Received 14 May 2001/Returned for modification 7 July 2001/Accepted 25 August 2001
The initial encounter of Leishmania cells and cells
from the immune system is fundamentally important in the outcome of
infection and determines disease development or resistance. We
evaluated the anti-Leishmania amazonensis response of naive
volunteers by using an in vitro priming (IVP) system and comparing the
responses following in vivo vaccination against the same parasite. In
vitro stimulation allowed us to distinguish two groups of individuals, those who produced small amounts of gamma interferon (IFN-
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.12.7453-7460.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Differences in Gamma Interferon Production In Vitro Predict the
Pace of the In Vivo Response to Leishmania amazonensis in
Healthy Volunteers
)
(n = 16) (low producers) and those who produced large
amounts of this cytokine (n = 16) (high producers).
IFN-
production was proportional to tumor necrosis factor alpha and
interleukin 10 (IL-10) levels but did not correlate with IL-5
production. Volunteers who produced small amounts of IFN-
in vitro
remained low producers 40 days after vaccination, whereas high
producers exhibited increased IFN-
production. However, 6 months
after vaccination, all individuals tested produced similarly high
levels of IFN-
upon stimulation of their peripheral blood
mononuclear cells with Leishmania promastigotes, indicating
that low in vitro producers respond slowly in vivo to vaccination. In
high IFN-
producers there was an increased frequency of activated
CD8+ T cells both in vitro and in vivo compared to the
frequency in low producers, and such cells were positive for IFN-
as
determined by intracellular staining. Such findings suggest that IVP
responses can be used to predict the pace of postvaccination responses
of test volunteers. Although all vaccinated individuals eventually have
a potent anti-Leishmania cell-mediated immunity (CMI)
response, a delay in mounting the CMI response may influence resistance against leishmaniasis.
*
Corresponding author. Mailing address: Centro de
Pesquisa Gonçalo Moniz (FIOCRUZ), Rua Valdemar Falcão, 121, Salvador, Bahia, Brazil, 40295-001. Phone: 55-71-356-4320, ext. 211. Fax: 55-71-356-2593. E-mail: barral{at}ufba.br.
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