Histopathology, parasite density and cell phenotypes of the popliteal lymph node in canine visceral leishmaniasis.
While enlargement of popliteal lymph nodes (LN) is frequently described in canine visceral leishmaniasis (CVL), there are few histopathologic studies of lymph nodes during this chronic immunopathological condition. Besides a detailed histopathologic analysis, we have characterized the parasite load and major immunophenotypic features of the LN in Leishmania (Leishmania) chagasi-infected dogs. Our major histopathological findings highlight that hypertrophy/hyperplasia of LN cortical and medullary zones was the principal characteristic observed in asymptomatic dogs (AD), whereas atrophy of LN cortical zone was predominant in symptomatic animals (SD). The LN parasite density detected by anti-Leishmania immunohistochemical assay or expressed as Leishman Donovan Units was also highly correlated with the skin parasitism, the most reliable parameter to decode the clinical status of CVL. The major LN immunophenotypic changes during ongoing CVL were an increased frequency of T-lymphocytes, particularly CD8+ T-cells, up-regulation of MHC-II expression by lymphocytes and decreased levels of CD21+ B-cells. Our findings further demonstrated that changes in the LN B-lymphocyte compartment exhibited a negative correlation with the skin parasite load. Conversely, we also showed evidence for a positive association between skin parasitism and LN T-cell-mediated immunity, suggesting that T-cells, especially CD8+ lymphocytes, may have a Type-2 immunological profile in this lymphoid tissue in response to CVL.
Giunchetti
Rodolfo Cordeiro
RC
Laboratório Imunopatologia, Núcleo de Pesquisas em Ciências Biológicas, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil. giunchetti@nupeb.ufop.br
Martins-Filho
Olindo Assis
OA
Carneiro
Cláudia Martins
CM
Mayrink
Wilson
W
Marques
Marcos José
MJ
Tafuri
Washington Luiz
WL
Corrêa-Oliveira
Rodrigo
R
Reis
Alexandre Barbosa
AB
D000818:Animals; D004283:Dog Diseases / Q000276:immunology / Q000469:parasitology* / Q000473:pathology*; D004285:Dogs; D005260:Female; D005434:Flow Cytometry / Q000662:veterinary; D007150:Immunohistochemistry / Q000662:veterinary; D016130:Immunophenotyping; D018314:Leishmania infantum / Q000276:immunology*; D007898:Leishmaniasis, Visceral / Q000276:immunology / Q000469:parasitology / Q000473:pathology / Q000662:veterinary*; D008198:Lymph Nodes / Q000473:pathology; D008206:Lymphatic Diseases / Q000276:immunology / Q000469:parasitology*; D008297:Male; D012867:Skin / Q000276:immunology / Q000469:parasitology