Identification of regulatory T cells during experimental Leishmania infantum infection

Leishmania Exosomes Modulate Innate and Adaptive Immune Responses through Effects on Monocytes and Dendritic Cells

“…Spleen parasitic loads were determined by limiting dilution assay as described elsewhere (22). Briefly, organs were collected, weighed, and homogenized individually in 2 ml HBSS.…”

Dynamicity of Immune Regulation during Visceral Leishmaniasis

“…CD8 + cells eliciting IL-10 have been found to possess remarkable immunosuppressive activity in autoimmune and infectious diseases (Noble et al, 2006 (Tang et al, 2008). During L. infantum infection in BALB/c mice, enrichment of CD4 + CD25 + FOXP3 + Treg cells have been shown in the draining lymph nodes and spleen cells (Rodrigues et al, 2009) suggesting their association with the disease. Involvement of CD4 + CD25 + Treg cells in progression of human VL and PKDL has also been reported (Saha et al, 2007;Katara et al, 2011).…”

Dynamics of immunosuppression in hamsters with experimental visceral leishmaniasis

“…We emphasize the importance of TGF-β in susceptibility and immunosuppression, a fact that has been demonstrated by the restoration of the proliferative response of non-adherent cells from infected hamsters treated with anti-TGF-β (8). It is attractive to speculate about the possible participation of CD4 + CD25 + -regulatory cells in immunosuppression during active VL in hamsters (9). According to our data, the immunosuppression observed in hamsters during active visceral leishmaniasis is an antigen-specific response since the initial phase of infection (after 72 h of infection), as determined by the absence of a lymphoproliferative response to Leishmania antigen and a preserved response to Con A. Interestingly, based on our results, the production of cytokines does not contribute to the development of immunosuppression in this experimental model.…”

“…Some host-related factors may be involved in the development of immunosuppression, which is partially attributed to Leishmania antigen-specific suppression, participation of non-adherent cells, possibly T lymphocytes (4), and reduced nitric oxide production by adherent cells from Leishmania-infected hamsters (5,6). Furthermore, an increased production of transforming growth factor-β (TGF-β) by the spleen or peripheral blood mononuclear cells of Leishmania-infected hamsters or Leishmania-infected mouse T cells has been related to immunosuppression (7)(8)(9) and to the impairment of protein kinase C activity or expansion of CD4 + CD25 + cells (8,9). However, using reverse transcriptase (RT)-PCR, dichotomy between the Th1 and Th2 cytokine profiles has not been observed during active VL in Leishmania donovani-infected hamsters (10 …”