مقالات پذیرفته شده در سومین کنگره بین المللی زیست پزشکی
The effect of dose on pathogenicity and immunogenicity of Leishmania tropica: suggestive evidences in an experimental model
The effect of dose on pathogenicity and immunogenicity of Leishmania tropica: suggestive evidences in an experimental model
Mosayeb Rostamian,1,*Hamid Mahmoudzadeh Niknam,2
1. Infectious Diseases Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran 2. Immunology Department, Pasteur Institute of Iran, Tehran, Iran
Introduction: Leishmania tropica is the causative agent of cutaneous leishmaniasis in many parts of the world including Iran. Previous reports indicated that the dose of parasites affects the outcome of disease in some Leishmania species. However, these effects are not clearly characterized on L. tropica. Here, the effect of parasite dose on L. tropica infection in BALB/c mice as experimental model was studied.
Methods: Two doses (high and low doses) of L. tropica were used for ear infection of mice and parasite load, lesion development, and cytokine responses were evaluated. The course of infection was monitored by bi-weekly measurement of thickness of ear or footpad by a dial-gauge caliper. Parasite load in draining lymph node and spleen were quantified by limiting dilution assay. For cytokine response detection, draining lymph nodes were removed, cultured, and stimulated by Leishmania antigens. Culture supernatants were harvested after 72 h and evaluated for interferon-γ (IFN-γ) and interleukin-10 (IL-10) production using commercial kits. Cells stimulated by concanavalin A (2 μg/ml) was used as positive control. Unstimulated cells were used as negative control.
Results: The results showed Footpad swelling developed from the high dose of L. tropica was significantly larger than low dose-infected mice. High dose in comparison to low dose resulted in higher load of parasite in draining lymph node. The dissemination of the parasite to the spleen occurs only in the high-dose infection at 4 months after infection. Also, higher levels of interleukin-10 and interferon-γ were observed in high dose-infected mice.
Conclusion: Altogether, our findings suggest that for L. tropica infection, only the high dose results in significant immune response and visceralization of the parasite in mice indicating that parasite dose is an important factor in pathogenesis and immunity in L. tropica infection.