immunology of infectious and parasitic diseases - XXXVII Congress ...

Characterization of fractions of Leishmania amazonensis extract with
immunomodulatory activity
Cintia Figueiredo de Araújo 1 ; Virgínia Maria Góes da Silva 2 ; Lain Carlos Pontes
de Carvalho 1
1 Centro de Pesquisa Gonçalo Moniz (IGM-FIOCRUZ); 2 Universidade Estadual
do Sudoeste da Bahia (UESB)
INTRODUCTION: Parasites of the genus Leishmania secrete molecules that
modulate the host immune system and thus contribute to the establishment of
the infection, changing the microbicidal activity of macrophages (Exp.
Parasitol.127: 46-51, 2011). Identification and functional characterization of
parasite molecules may clarify the pathogenesis of leishmaniasis and contribute
to the development of prophylactic and therapeutic methods. The aim of this
study was to purify and characterize molecules with immunomodulatory activity
in extracts of Leishmania amazonensis amastigotes.
METHODS AND RESULTS: L. amazonensis extract (LaE) was prepared
(Infect. Immun. 79: 1236-1243, 2011) and subjected to non-denaturing
electrophoresis on 12% polyacrylamide gel. Fractions with molecules with
apparent weights of 68 kDa, 45 kDa, 36 kDa and 28 kDa were chosen, based
on previous results and processed according to a previously described protocol
(PloS One 4: e5820, 2009). To analyze the immunomodulatory effect of the
fractions, BALB/c mice (n=8) were injected intradermally with saline or 5 µg in
50 µL of LaE or of the fractions. After one week they were inoculated in the right
hind footpad with 10 7 promastigotes of L. braziliensis in stationary phase. The
evolution of the lesions was monitored weekly by measuring with a digital
caliper, until six weeks after infection. The fractions of 68 kDa and 28 kDa
increased significantly the lesion from the second to the sixth week (p