Canine leishmaniosis. Modulation of macrophage/lymphocyte interactions by L. infantum.
Canine leishmaniosis, caused by Leishmania infantum, is a systemic disease with variable clinical signs and a progressive evolution. This disease is characterized by impaired T cell-mediated immune response, which has been associated with disease chronicity and high mortality. Protective immunity against leishmaniosis is thought to be mediated by T cell and cytokine production. The T cell activation requires a primary signal delivered by the major histocompatibility complex (MHC) molecules present on the surface of antigen presenting cells, and a non-specific signal generated by co-stimulatory molecules. To characterize canine immune responses in the presence of L. infantum parasites or their antigens, in vitro cell cultures of canine macrophages and lymphocytes were established, and the macrophages presenting MHC class II molecules were evaluated as well as the expression of IL-12 and CD80-86 co-stimulatory molecules and nitric oxide production. The results showed for the first time the up-regulation of MHC class II molecules on the surface in canine peripheral blood monocyte-derived macrophages during L. infantum infection in the presence of lymphocytes. In addition, a lack of co-stimulatory expression and a reduced release of nitric oxide were observed, suggesting a loss of T cell function and consequently an inactivation of the macrophage oxidative burst which, in turn, favors the survival of Leishmania. These results constitute a new contribution for the understanding of the interactions between L. infantum and the canine immune system.
Unidade de Ensino e Investigação de Parasitologia Médica, Centro de Malária e Outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira 100, 1349-008 Lisboa, Portugal.
Suraya
S
Diaz
Isabel Pereira
IP
da Fonseca
Armanda
A
Rodrigues
Catarina
C
Martins
Clara
C
Cartaxeiro
Maria Jesus
MJ
Silva
Teresa Villa
TV
de Brito
Graça
G
Alexandre-Pires
Gabriela M
GM
Santos-Gomes
D000818:Animals; D018122:B7-1 Antigen / Q000235:genetics / Q000378:metabolism; D051940:B7-2 Antigen / Q000235:genetics / Q000378:metabolism; D004283:Dog Diseases / Q000469:parasitology*; D004285:Dogs; D005260:Female; D005786:Gene Expression Regulation; D005802:Genes, MHC Class II / Q000502:physiology; D018664:Interleukin-12 / Q000235:genetics / Q000378:metabolism; D018314:Leishmania infantum / Q000502:physiology*; D007898:Leishmaniasis, Visceral / Q000469:parasitology / Q000662:veterinary*; D008264:Macrophages / Q000469:parasitology*; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D016897:Respiratory Burst / Q000502:physiology
D018122:B7-1 Antigen; D051940:B7-2 Antigen; D018664:Interleukin-12; D009569:Nitric Oxide