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

13173 - COMPARISON OF ANTI-LEISHMANIAL IGG ANTIBODIES PROFILE
IN SERA FROM BRAZILIAN PATIENTS WITH VISCERAL LEISHMANIASIS
AND INDIVIDUALS PRESENTING ASYMPTOMATIC INFECTIONS
LUIZ GUSTAVO ARAUJO GARDINASSI 1 ; GUSTAVO ROCHA GARCIA 1 ;
SANDRA REGINA MARUYAMA 1 ; FERNANDO OLIVEIRA DA SILVA 2 ;
CARLOS HENRIQUE NERY COSTA 2 ; ROQUE PACHECO DE ALMEIDA 3 ;
AMÉLIA MARIA RIBEIRO DE JESUS 3 ; ISABEL KINNEY FERREIRA DE
MIRANDA SANTOS 1
1 Faculdade de Medicina de Ribeirão Preto - USP, Departamento de Bioquímica
e Imunologia; 2 Instituto de Doenças Tropicais Natan Portella - UFPI; 3 Centro de
Ciências Biológicas e da Saúde – UFS, Depto. de Medicina Interna e Patologia
Introduction: It is intriguing that the majority of infections with the etiological
agent of visceral leishmaniasis (VL), Leishmania infantum, do not result in
disease. The scientific consensus is that antibodies do not have a role in this
outcome and, in fact, participate in susceptibility to VL; however recent studies
challenge this view. We aim to test the hypothesis that individuals presenting
with asymptomatic infections with L. infantum remain so because they produce
antibodies with functional properties that differ from those produced by
individuals who develop VL.
Methods and Results: With immunoblots and ELISAs we will study the
correlation of different outcomes of infections with L. infantum (VL or
asymptomatic infection) with antigen reactivity profiles and titers of IgG1-4
antibodies in serum from humans of different ages. Description of patterns of
IgG antibody responses will be refined by probing sera with a protein microarray
constructed with approximately 2300 secreted or plasma membrane proteins of
L. infantum. Sera were collected from 208 kala-azar patients, 197 from
individuals with asymptomatic infection and 138 from healthy donors, all living in
endemic areas. Western blots were performed between soluble antigens (SLA)
of L. infantum and sera from individuals presenting with VL or infected
asymptomatically. Indeed, sera from VL patients recognize a set of antigens
that is distinct from those recognized by sera from infected, asymptomatic
individuals, and the pattern of recognition differs both by specificity and
intensity. ELISAs were performed to screen IgG antibodies against SLA