CD4+ Th1 cells induced by dendritic cell-based immunotherapy in mice chronically infected with Leishmania amazonensis do not promote healing.
The susceptibility of mice to Leishmania amazonensis infection is thought to result from an inability to develop a Th1 response. Our data show that the low levels of gamma interferon (IFN-gamma) produced by the draining lymph node (DLN) cells of chronically infected mice could be enhanced in vitro and in vivo with L. amazonensis antigen-pulsed bone marrow-derived dendritic cells (BM-DC) and the Th1-promoting cytokine interleukin-12 (IL-12). Given intralesionally to chronically infected mice, this treatment induced the upregulation of mRNA levels for IFN-gamma, the transcription factor T-box expressed in T cells, and IL-12 receptor beta 2 in CD4(+) T cells from the DLN and an increase in parasite-specific immunoglobulin G2a in the serum. However, this Th1 response was not associated with healing, and the antigen-specific enhancement of IFN-gamma production remained impaired in the DLN. However, addition of IL-12 to the in vitro recall response was able to recover this defect, suggesting that antigen-presenting cell-derived IL-12 production may be limited in infected mice. This was supported by the fact that L. amazonensis amastigotes limited the production of IL-12p40 from BM-DC in vitro. Altogether, our data indicate that the immune response of mice chronically infected with L. amazonensis can be enhanced towards a Th1 phenotype but that the presence of Th1 CD4(+) T cells does not promote healing. This suggests that the phenotype of the CD4(+) T cells may not always be indicative of protection to L. amazonensis infection. Furthermore, our data support growing evidence that antigen-presenting cell function, such as IL-12 production, may limit the immune response in L. amazonensis-infected mice.
Department of Veterinary Pathology, College of Veterinary Medicine, Iowa State University, Ames, IA 50011-1250, USA.
Yannick F
YF
Vanloubbeeck
Amanda E
AE
Ramer
Fei
F
Jie
Douglas E
DE
Jones
D000818:Animals; D001854:Bone Marrow Cells; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002908:Chronic Disease; D003713:Dendritic Cells / Q000276:immunology*; D005260:Female; D007167:Immunotherapy / Q000379:methods*; D007371:Interferon-gamma / Q000378:metabolism; D018664:Interleukin-12 / Q000378:metabolism; D053762:Interleukin-12 Subunit p40; D007891:Leishmania / Q000276:immunology; D016773:Leishmaniasis, Cutaneous / Q000276:immunology / Q000628:therapy*; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D016513:Mice, SCID; D021122:Protein Subunits / Q000378:metabolism; D018417:Th1 Cells / Q000276:immunology*; D017211:Treatment Failure
D053762:Interleukin-12 Subunit p40; D021122:Protein Subunits; D018664:Interleukin-12; D007371:Interferon-gamma