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

IMMUNOLOGICAL PARAMETERS ASSOCIATED TO GRANULOMATOUS
PATHOLOGY AFTER SCHISTOSOMA MANSONI INFECTION AND
REINFECTION IN TWO MURINE STRAINS.
GARDENIA BRAZ FIGUEIREDO DE CARVALHO 1 ; ANGÉLICA SAMMER
LALLO DIAS 1 ; CLARICE CARVALHO ALVES 1 ; CRISTINA TOSCANO
FONSECA 1,2 .
1 Centro de Pesquisas René Rachou, Fiocruz-MG, Belo Horizonte, Minas
Gerais, Brazil; 2 Instituto Nacional de Ciências e Tecnologia em Doenças
Tropicais (INCT-DT), Brazil.
Introduction: In schistosomiasis, host immune system plays an important role
in both parasite development and elimination. Also difference in immune
response has been associated to resistance or susceptibility for the disease and
to the different clinical forms observed in infected individuals. Granulomatous
reaction around eggs is the major pathology associated with schistosome
infection, and once again the host immune system plays an important role in
granuloma development and modulation. To understand this complex hostparasite
interaction we analyzed parasitological, pathological and
immunological parameters associated with infection/reinfection in two murine
strains: C57BL/6 and Balb-c. Methods and Results: Thirty C57BL/6 mice and
Balb-c mice were infected with 30 S. mansoni cercariae, 45 days after infection,
15 animals were perfused to determine worm burden. The other animals were
treated with praziquantel (400mg/Kg) and thirty days after treatment mice were
reinfected with 30 cercariae. Forty five days after reinfection, worm burden
recovered were determined. Any difference in worm burden was observed
between strains after infection or reinfection. Sixty days after
infection/reinfection granuloma area was determined in 50 granulomas from
each group with a single well-defined egg and at exudative-productive stage.
Significant reduction in granuloma area was observed in C57BL/6 infected mice
in comparison to Balb infected mice (31%). Also a significant reduction in
granuloma area was observed in both strains after reinfection (52% in Balb and
36% in C57BL/6). Sixty days after infection/reinfection spleen cells from
individual animals were culture in the presence of soluble eggs antigens and
cytokines were measured in culture supernatant. Significant IL-10 production
was detected in C57BL/6 mice (p=0,03), in contrast significant IL-13 production
was detected in Balb-c infected mice (p=0,04). Any significant difference in
cytokine production was between infected and reinfected mice. Conclusion:
Our results indicate that although the difference in the genetic background did
not influence parasite survival, it leads to differences in pathology that might be
related to the different cytokine profile observed between strains. Additional
studies are necessary to clarify the mechanisms involved in granuloma
modulation after reinfection.