Adjuvant Effect of Leishmania major Promastigotes on the Immune Response of Mice to Ovalbumin

ABSTRACT The immune responses of mice immunized with ovalbumin (OVA) together with killed L. major (KLM) promastigotes as adjuvant were studied. Three doses (5 × 10 7 , 1 × 10 8 and 2 × 10 8 ) of KLM combined with OVA (100 µg) were injected into the groups of C57BL/6 mice. BCG and complete Freund's adjuvant (CFA) were used as control adjuvants. Lymphocyte proliferation and antibody titers were determined, and IFN-γ and IL-4 were measured in the supernatants of lymph node cell cultures. Results showed that immunization using OVA mixed with KLM enhanced the in vitro proliferative response of T-cells to the antigen and resulted in the production of increased levels of IFN-γ (2800-3700 pg/ml) relative to the mice injected with OVA alone (1750 pg/ml). In the mice receiving OVA + 5 × 10 7 KLM, the production of IL-4 remained lower (18, 20 pg/ml) than OVA alone (105, 109 pg/ml) and almost was similar to that of observed in mice inoculated with OVA + BCG, leading to high IFN-γ/IL-4 ratios. Using higher doses of KLM (1 × 10 8 ), the IL-4 responses were of the same magnitude as or higher than the responses of mice inoculated with OVA + CFA. Antibody titers to OVA were also strongly boosted at the highest KLM dose. These findings indicate that KLM may function as an adjuvant, and its dose plays a role in the eventual outcome of the response. Inoculation of the mice with a low dose of KLM (5 × 10 7 ) tends to promote a Th1-type response. Iran. Biomed. J. 6 (4): 123-128, 200

Expansion of <FONT FACE=Symbol>gd</font><FONT FACE=Symbol> </font>T cells in patients infected with cutaneous leishmaniasis with and without glucantime therapy

The expansion of <FONT FACE=Symbol>gd </font>T cells in patients with active cutaneous leishmaniasis, with or without glucantime therapy, was investigated. Twenty patients with local cutaneous leishmaniasis including glucantime-treated (n=10) and untreated (n=10) patients were selected. The controls were healthy individuals (n=10) living in endemic areas. Whole blood was obtained and the T cell subpopulations were analyzed by flow cytometry. Significantly more <FONT FACE=Symbol>gd</FONT> CD3+ T cells were observed in untreated patients (15.9% ± 5.9), when compared with glucantime-treated patients (4.6% ± 1.4) and controls (5.3% ± 2.3). On the other hand, when the percentages of ab CD3+ T-cells were analyzed different results were obtained. A significant increase in <FONT FACE=Symbol>ab</FONT> T cells was seen in glucantime-treated patients (62.4% ± 7.6), when compared to the untreated patients (55.7% ± 5.5) and controls (55.1% ± 9.6). The percentage of total CD3+ T cells was statistically greater in both glucantime-treated (68.8% ± 7.4) and untreated patients (73.4% ± 5.9) when compared to the controls (61% ± 10.3). These results are consistent with previous results on the expansion of <FONT FACE=Symbol>gd</FONT>T cells during the course of cutaneous leishmaniasis. They also indicate that glucantime therapy can reverse the expansion of <FONT FACE=Symbol>gd</FONT>T cells and as a result increase the percentages of <FONT FACE=Symbol>ab</FONT> CD3+ T cells

Protective vaccination against experimental canine visceral leishmaniasis using a combination of DNA and protein immunization with cysteine proteinases type I and II of L. infantum.

Leishmania infantum is known to be associated with visceral leishmaniasis in Iran and canids are natural reservoirs. Control of disease in dogs appears to be one of the most effective approaches for interrupting the domestic cycle of the disease. In search for successful vaccine strategies, we evaluated the cysteine proteinases (CPs) type I and II using a heterologous prime-boost regime for vaccination against experimental visceral leishmaniasis in dogs. Following vaccination and challenge, dogs were followed for 12 months. Ten dogs vaccinated by prime/boost with DNA/recombinant CPs (in combination with CpG ODN and Montanide 720) remained free of infection in their bone morrow. In contrast, three out of four dogs in the control groups had infection in their bone marrow. The peripheral lymphocytes from protected animals had generally higher proliferation responses to F/T antigen, recombinant CPA (rCPA) and recombinant CPB (rCPB) than controls. During post-challenge period, the difference in stimulation index is significant (p<0.05) on months 11 and 12 to F/T antigens, all months for rCPA and 5, 7, 9, 11 and 12 months for rCPB. Analysis of cytokine mRNA level suggested that vaccinated dogs had elevated IFN-gamma mRNA in peripheral blood mononuclear cells (PBMC), whereas there was a consistent increase in the level of IL-10 in the control groups and some vaccinated dogs. The level of total IgG and IgG2, but not IgG1, to rCPA and rCPB was significantly higher in the vaccinated group (p<0.05) than the control groups. We also showed that with the exception of one dog, all dogs in the vaccinated group in comparison to control dogs had strong DTH responses. We propose that the combination of DNA and recombinant protein vaccination using CPs could be instrumental to control (VL) in dogs