Determination of the cytokine profile in American cutaneous leishmaniasis using the polymerase chain reaction

Immunological determinants of clinical outcome in Peruvian patients with tegumentary leishmaniasis treated with pentavalent antimonials

The mechanisms linking the immune response to cutaneous and mucosal leishmaniasis (CL and ML, respectively) lesions and the response to treatment are incompletely understood. Our aims were to prospectively assess, by quantitative reverse transcription-PCR, the levels of mRNA for gamma interferon, tumor necrosis factor alpha, interleukin-10 (IL-10), IL-4, and IL-13, as well as the presence of T cells (CD2) and macrophages (CD68), in CL and ML lesions and to follow their changes in response to treatment with pentavalent antimonials. The leishmanin skin test (LST) was performed on all CL and ML patients before treatment. The patient population included individuals living in areas of Peru where the disease is endemic, i.e., 129 with CL and 43 with ML. Compared to CL patients, the LST induration size was larger, the levels of all cytokine mRNAs but IL-10 were higher, T-cell mRNA was similar, and macrophage mRNA was lower in ML patients. The proportion of CL patients with an LST induration size of >8 mm was higher among responders to treatment. In CL, the pretreatment levels of cytokine mRNAs did not discriminate between responders and nonresponders; however, treatment was more often accompanied by a reduction in the levels of T-cell and cytokine mRNAs in responders than in nonresponders. Furthermore, the production of cytokines per T cell and macrophage decreased with treatment but IL-10 production remained high in nonresponders. Overall, these findings point to complex relationships among New World Leishmania parasites, skin and mucosal immune responses, and treatment outcome. The persistence of high levels of IL-10 in CL is characteristically associated with a poor response to treatment.

Accelerated control of visceral Leishmania donovani infection in interleukin-6-deficient mice

In patients with visceral leishmaniasis, increased levels of circulating interleukin-6 (IL-6) regularly accompany fully expressed, progressive infections (kala-azar). To experimentally test the role of IL-6, responses to an intracellular Leishmania donovani infection in the livers of IL-6(-/-) and wild-type mice were compared. IL-6(-/-) mice showed an enhanced control of the infection and earlier, rapid parasite killing along with additional evidence of a stimulated antileishmanial Th1-cell-type response: increased levels of circulating gamma interferon, accelerated granuloma assembly, and heightened responsiveness to chemotherapy. In this model of visceral leishmaniasis, IL-6 appears to act in a suppressive, macrophage-deactivating fashion, which identifies it as a potential target for therapeutic blockade.

Monocyte cytokine and costimulatory molecule expression in patients infected with Leishmania mexicana

Leishmania mexicana causes localized and diffuse cutaneous leishmaniasis. Patients with localized cutaneous leishmaniasis (LCL) develop a benign disease, whereas patients with diffuse cutaneous leishmaniasis (DCL) suffer from a progressive disease associated with anergy of the cellular response towards Leishmania antigens. We evaluated the production of the interleukins (IL) IL-12, IL-15, IL-18 and tumour necrosis factor-alpha (TNF-alpha) and the expression of the costimulatory molecules CD40, B7-1 and B7-2 in monocytes from LCL and DCL patients, stimulated in vitro with Leishmania mexicana lipophosphoglycan (LPG) for 18 h. LCL monocytes significantly increased TNF-alpha, IL-15 and IL-18 production, and this increase was associated with reduced amounts of IL-12. DCL monocytes produced no IL-15 or IL-18 and showed a decreasing tendency of TNF-alpha and IL-12 production as the severity of the disease increased. No difference was observed in the expression of CD40 and B7-1 between both groups of patients, yet B7-2 expression was significantly augmented in DCL patients. It remains to be established if this elevated B7-2 expression in DCL patients is cause or consequence of the Th2-type immune response that characterizes these patients. These data suggest that the diminished ability of the monocytes from DCL patients to produce cell-activating innate proinflammatory cytokines when stimulated with LPG is a possible cause for disease progression.

Analysis of the CC chemokine receptor 5 delta32 polymorphism in a Brazilian population with cutaneous leishmaniasis

Patients with mucocutaneous leishmaniasis (MCL) show a vigorous T-cell immune response against Leishmania braziliensis. Because the Th response is associated with inflammation, the non-functional CC chemokine receptor 5 (CCR5) may rely in a less severe inflammatory state. The aim of this study was to investigate the CCR5 gene in a Brazilian population with leishmaniasis compared with healthy control subjects and to determine the progression from cutaneous to MCL in the Delta32 allele carriers. Among 100 patients with Montenegro skin test and indirect immunofluorescence assay (IIF) values positive for leishmaniasis, there were 32% women and 68% men. The patients were 89% CCR5/CCR5, 10% CCR5/Delta32, and 1% Delta32/Delta32, while healthy subjects showed a 91% incidence of CCR5/CCR5, 8% of CCR5/Delta32, and 1% of Delta32/Delta32. The CCR5/CCR5 patients (89%) showed a large spectrum of clinical manifestations, where 22.47% had active mucous lesions and 77.53% had cutaneous lesions. In this work, the Delta32 allele carriers (10%) showed only cutaneous manifestations when compared with wild-type individuals. Finally, with regard to the Delta32 allele carriers, a less severe spectrum of clinical manifestations was observed in comparison with wild-type individuals. Although a lack of mucocutaneous lesions was evident among Delta32 allele carriers, the number of individuals studied was small. Therefore, further investigations are needed to elucidate the role of CCR5 in the clinical aspects of leishmaniasis.

Inducible nitric oxide synthase and cytokine pattern in lesions of patients with American cutaneous leishmaniasis

American tegumentary leishmaniasis has three forms: localized (LCL), found in resistant individuals; diffuse (DCL), found in susceptible individuals; and intermediate cutaneous leishmaniasis (ICL), found in individuals with exacerbated immunity. We evaluated cytokines and inducible nitric oxide synthase (iNOS) in lesions of LCL, ICL and DCL using immunohistochemistry. LCL granulomas showed a preponderance of interferon (IFN)-gamma and interleukin (IL)-12 expression, whereas ICL granulomas had more IL-4-, IL-10- and mainly transforming growth factor (TGF)-beta1-expressing cells. Higher densities of iNOS+ cells were observed in ICL and LCL than in DCL. iNOS was also expressed in keratinocytes of LCL and ICL lesions, and in epidermal dendritic cells of ICL lesions. In LCL and ICL, most keratinocytes expressed IL-12 and a portion expressed IFN-gamma. IL-12+ and IFN-gamma+ dendritic cells were absent or sparse in LCL and ICL epidermis. Our results show the importance of iNOS, IL-12 and INF-gamma in LCL and ICL lesions, emphasizing the existence of a mixed cytokine pattern in ICL different from the Th1 and Th2 responses established in LCL and DCL lesions.

Differential effects of antigens from L. braziliensis isolates from disseminated and cutaneous leishmaniasis on in vitro cytokine production

Background

Disseminated leishmaniasis is an emerging infectious disease, mostly due to L. braziliensis, which has clinical and histopathological features distinct from cutaneous leishmaniasis.

Methods

In the current study we evaluated the in vitro production of the cytokines IFN-γ, TNF-α, IL-5 and IL-10 by peripheral blood mononuclear cells (PBMC) from 15 disseminated leishmaniasis and 24 cutaneous leishmaniasis patients upon stimulation with L. braziliensis antigens genotyped as disseminated leishmaniasis or cutaneous leishmaniasis isolates.

Results

Regardless of the source of L. braziliensis antigens, PBMC from cutaneous leishmaniasis patients produced significantly higher IFN-γ than PBMC from disseminated leishmaniasis patients. Levels of TNF-α by PBMC from cutaneous leishmaniasis patients were significantly higher than disseminated leishmaniasis patients only when stimulated by genotyped cutaneous leishmaniasis antigens. The levels of IL-5 and IL-10 production by PBMC were very low and similar in PBMCs from both disseminated leishmaniasis and cutaneous leishmaniasis patients. The immune response of each patient evaluated by the two L. braziliensis antigens was assessed in a paired analysis in which we showed that L. braziliensis genotyped as disseminated leishmaniasis isolate was more potent than L. braziliensis genotyped as cutaneous leishmaniasis isolate in triggering IFN-γ and TNF-α production in both diseases and IL-5 only in cutaneous leishmaniasis patients.

Conclusion

This study provides evidence that antigens prepared from genotypically distinct strains of L. braziliensis induce different degrees of immune response. It also indicates that both parasite and host play a role in the outcome of L. braziliensis infection.

Decreased in situ expression of interleukin-10 receptor is correlated with the exacerbated inflammatory and cytotoxic responses observed in mucosal leishmaniasis

Human infection with Leishmania braziliensis can lead to cutaneous leishmaniasis (CL) or mucosal leishmaniasis (ML). We hypothesize that the intense tissue destruction observed in ML is a consequence of an uncontrolled exacerbated inflammatory immune response, with cytotoxic activity. For the first time, this work identifies the cellular sources of inflammatory and antiinflammatory cytokines, the expression of effector molecules, and the expression of interleukin-10 (IL-10) receptor in ML and CL lesions by using confocal microscopy. ML lesions displayed a higher number of gamma interferon (IFN-gamma)-producing cells than did CL lesions. In both ML and CL, CD4+ cells represented the majority of IFN-gamma-producing cells, followed by CD8+ cells and CD4- CD8- cells. The numbers of tumor necrosis factor alpha-positive cells, as well as those of IL-10-producing cells, were similar in ML and CL lesions. The effector molecule granzyme A showed greater expression in ML than in CL lesions, while inducible nitric oxide synthase did not. Finally, the expression of IL-10 receptor was lower in ML than in CL lesions. Thus, our data identified distinct cytokine and cell population profiles for CL versus ML patients and provide a possible mechanism for the development of ML disease through the demonstration that low expression of IL-10 receptor is present in conjunction with a cytotoxic and inflammatory profile in ML.

What about Th1/Th2 in cutaneous leishmaniasis vaccine discovery?

The T helper cell type 1 (Th1) response is essential to resist leishmaniasis, whereas the Th2 response favors the disease. However, many leishmanial antigens, which stimulate a Th1 immune response during the disease or even after the disease is cured, have been shown to have no protective action. Paradoxically, antigens associated with an early Th2 response have been found to be highly protective if the Th1 response to them is generated before infection. Therefore, finding disease-associated Th2 antigens and inducing a Th1 immune response to them using defined vaccination protocols is an interesting unorthodox alternative approach to the discovery of a leishmania vaccine.

Cellular immunophenotyping of exfoliative dermatitis in canine leishmaniosis (Leishmania infantum)

Lymphocyte subsets, major histocompatibility complex (MHC)-II expressing cells and number of amastigotes in the epidermis and dermis were investigated immunohistochemically in 48 dogs with patent leishmaniosis, with or without exfoliative dermatitis (ED) to study the immunopathogenesis of this common cutaneous form of the disease. Skin biopsies were obtained and compared for ED sites (group A, n = 26), normal-appearing skin from the same animals (group B, n = 24), and leishmanial dogs not exhibiting ED (group C, n = 22), and normal controls (group D, n = 22). The CD3+, CD45RA+, CD4+, CD8+ (CD8a+), CD21+, and MHC-II+ cells and leishmania amastigotes were identified immunohistochemically and counted with the aid of an image analysis system. Pyogranulomatous to granulomatous dermatitis, expressed in various histopathological patterns, was noticed in all groups A and B and in half of group C dogs. In the epidermis, the low number of T-cells and their subsets did not differ significantly between groups A and B, but CD8+ outnumbered CD4+ lymphocytes in both groups. MHC-II+ expression on epidermal keratinocytes was intense in the skin with and without lesions from dogs with ED but not in group C dogs. CD3+, CD8+ and MHC-II+ cells were fewer in group C compared to group A and B dogs. In the dermis, CD3+ cells in group A animals were mainly represented by the CD8+. CD45RA+ and CD21+ cells were also seen in high numbers. MHC-II expression, potentially in lymphocytes, fibroblasts, dendritic cells, and macrophages was intense. The numbers of all cellular subpopulations in the dermis were significantly different between the groups, being highest in group A and lowest in group D. In sebaceous adenitis sites, CD4+ outnumbered CD8+ cells in contrast to the neighbouring dermis and the epidermis. The number of CD21+ and CD45RA+ cells was much lower in the inflamed sebaceous glands compared to the dermis. Finally, the number of amastigotes in the normal-appearing skin was significantly higher in the ED dogs (group B) than in those not exhibiting this cutaneous form of the disease (group C).

Role of HLA class II alleles in susceptibility to and protection from localized cutaneous leishmaniasis

Localized cutaneous leishmaniasis (LCL) is the prevalent form of leishmaniasis in Mexico. It is limited to the skin; reversible upon treatment and the host cellular immune response is intact. Several genes that influence the expression of LCL have been described in the mouse. In humans, we, as well as others, have demonstrated that HLA-DQ3 antigens seem to play some role in host susceptibility. We therefore analyzed at the DNA level, the class II loci of the same patients that were previously studied by serology. The purpose of this study was to assess the contribution of HLA DR, DQ, and DP genes in the protection and/or the susceptibility to LCL. Sixty-five patients with LCL from Comalcalco, state of Tabasco, were recruited and 100 healthy controls were included for comparison. All were Mexican Mestizos. DRB1, DQA1, DQB1, DPA1, and DPB1 alleles were typed using two different methods: PCR-SSO and PCR-SSP. Results indicate that class II genes are relevant for the expression of LCL and several loci contribute independently and sinergically. DRB1*0407 participates in susceptibility with an etiological fraction (EF) of 20% and an odds ratio (OR) of 2.92. Two additional susceptibility genes were found. These are located to the DP locus: DPA1*0401 (OR = 10.07; EF=7%) and DPB1*0101 (OR = 5.99 EF = 13%). Resistance was found associated to DPB1*0401, thus *0401 "motif" could be an ideal candidate for the development of a vaccine. DR2 (DRB1*1500+DRB1*1600) has also a significant p for protection, suggesting that the sequence common to this group of antigens may anchor parasite peptides which trigger a protective response.

Clinical and immunopathological spectrum of American cutaneous leishmaniasis with special reference to the disease in Amazonian Brazil: a review

The wide variety of Leishmania species responsible for human American cutaneous leishmaniasis combined with the immune mechanisms of the host results in a large spectrum of clinical, histopathological, and immunopathological manifestations. At the middle of this spectrum are the most frequent cases of localized cutaneous leishmaniasis (LCL) caused by members of the subgenera Leishmania and Viannia, which respond well to conventional therapy. The two pathogenicity extremes of the spectrum generally recognized are represented at the hypersensitivity pole by mucocutaneous leishmaniasis (MCL) and at the hyposensitivity pole by anergic diffuse cutaneous leishmaniasis (ADCL). Following the present study on the clinical, histopathological and immunopathological features of cutaneous leishmaniasis in Amazonian Brazil, we propose the use of the term "borderline disseminated cutaneous leishmaniasis" for the disseminated form of the disease, due to parasites of the subgenera Leishmania and Viannia, which might be regarded as intermediate between LCL and the extreme pathogenicity poles MCL and ADCL.

Therapy of Venezuelan patients with severe mucocutaneous or early lesions of diffuse cutaneous leishmaniasis with a vaccine containing pasteurized Leishmania promastigotes and bacillus Calmette-Guerin: preliminary report

Severe mucocutaneous (MCL) and diffuse (DCL) forms of American cutaneous leishmaniasis (ACL) are infrequent in Venezuela. Chemotherapy produces only transitory remission in DCL, and occasional treatment failures are observed in MCL. We have evaluated therapy with an experimental vaccine in patients with severe leishmaniasis. Four patients with MCL and 3 with early DCL were treated with monthly intradermal injections of a vaccine containing promastigotes of Leishmania (Viannia) braziliensis killed by pasteurization and viable Bacillus Calmette- Guerin. Clinical and immunological responses were evaluated. Integrity of protein constituents in extracts of pasteurized promastigotes was evaluated by gel electrophoresis. Complete remission of lesions occurred after 5-9 injections in patients with MCL or 7-10 injections in patients with early DCL. DCL patients developed positive skin reactions, average size 18.7 mm. All have been free of active lesions for at least 10 months. Adverse effects of the vaccine were limited to local reactivity to BCG at the injection sites and fever in 2 patients. Extracts of pasteurized and fresh promastigotes did not reveal differences in the integrity of protein components detectable by gel electrophoresis. Immunotherapy with this modified vaccine offers an effective, safe option for the treatment of patients who do not respond to immunotherapy with vaccine containing autoclaved parasites or to chemotherapy.

Variations in the serum levels of soluble CD23, nitric oxide and IgE across the spectrum of American cutaneous leishmaniasis

Serum IgE levels and the expression of low affinity receptor for IgE (Fc epsilon RII/CD23) are increased in cutaneous leishmaniasis. The ligation of CD23 receptor by IgE-anti-IgE immune complexes results in nitric oxide (NO) production, which is a critical leishmanicidal factor. Human monocytes/macrophages express Fc epsilon RII/CD23 after activation with IFN-gamma and IL-4. In the present study, we assessed the relationship between NO, total and Leishmania-specific IgE and soluble CD23 across the clinical spectrum of American cutaneous leishmaniasis (ACL). Sixty-nine ACL patients and 22 endemic controls were studied. NO concentration was estimated using the Greiss method. Soluble CD23, total IgE and anti-Leishmania IgE levels were measured using ELISA. Soluble CD23 was increased in the four patient groups (0.001<P<0.05) compared by the Mann-Whitney test to healthy subjects, particularly in mucocutaneous leishmaniasis (MCL) and diffuse cutaneous leishmaniasis (DCL) patients. Total IgE levels were higher in ACL patients (P<0.0001). Anti-Leishmania IgE showed a similar tendency, where MCL and DCL patients had greater levels. All patients groups, except intermediate or chronic cutaneous leishmaniasis (ICL) patients, showed elevated levels of NO(2)(-)/NO(3)(-) compared to healthy individuals (0.001<P<0.01). Interestingly, ICL patients did not produce significant levels of NO(2)(-)/NO(3)(-). ACL patients showed a significant positive correlation between soluble CD23 and anti-Leishmania IgE. DCL patients showed a positive correlation between both parameters. Overall results suggest that sCD23, IgE and NO may play different roles across the ACL spectrum.

Leishmania lipophosphoglycan (LPG) activates NK cells through toll-like receptor-2

Toll-like receptors (TLRs) mediate the cellular response to conserved molecular patterns shared by microorganisms. We report that TLR-2 on human NK cells is upregulated and stimulated by Leishmania major lipophosphoglycan (LPG), a phosphoglycan belonging to a family of unique Leishmania glycoconjugates. We found that purified L. major LPG upregulates both mRNA and the membrane expression of TLR-2 in NK cells. Additionally, IFN-gamma and TNF-alpha production and nuclear translocation of NF-kappaB was enhanced. The activation effect was more intense with LPG purified from infectious metacyclic parasites than from noninfectious procyclic Leishmania. Since the difference between the molecules derived from these two stages of the parasite growth cycle lies exclusively in the number of phosphosaccharide repeat domains and in the composition of glycan side chains that branch off these domains, we propose that TLR-2 possibly distinguishes between phosphorylated glycan repeats on LPG molecules. The effect of LPG on cytokine production and on membrane expression of TLR-2 could be blocked with F(ab')2 fragments of the mAb against LPG (WIC 79.3). Confocal microscopy demonstrated the co-localization of LPG and TLR-2 on the NK cell membrane. Binding of LPG to TLR-2 in NK cells was demonstrated by immunoprecipitations done with anti-TLR-2 and anti-LPG mAb followed by immunoblotting with anti-LPG and anti-TLR-2, respectively. Both antibodies recognized the immune complexes. These results suggest that NK cells are capable of recognition of, and activation by, Leishmania LPG through TLR-2, enabling them to participate autonomously in the innate immune system and thereby increasing the effective destruction of the parasite.

Impaired expression of inflammatory cytokines and chemokines at early stages of infection with Leishmania amazonensis

Infection of mice with Leishmania major results in disease progression or resolution, largely depending on the genetic backgrounds of the mouse strains. Infection with Leishmania amazonensis, on the other hand, causes progressive cutaneous lesions in most inbred strains of mice. We hypothesized that deficient activation of early immune responses contributes to the pathogenesis in L. amazonensis-infected mice. To distinguish early molecular events that determine the outcome of Leishmania infections, we examined cytokine gene expression in C57BL/6 mice infected with either L. amazonensis or L. major (a healing model). After 2 to 4 weeks, L. amazonensis-infected mice had significantly delayed and depressed expression of inflammatory cytokines (interleukin-12 [IL-12], gamma interferon, IL-1 alpha, IL-1 beta), CC chemokines (CC chemokine ligand 3 [CCL3]/macrophage inflammatory protein 1 alpha [MIP-1 alpha], CCL4/MIP-1 beta, CCL5/RANTES, MIP-2), and chemokine receptors (CCR1, CCR2, CCR5) in foot tissues and draining lymph nodes compared to the expression in L. major-infected controls. These findings correlated with defective T-cell responsiveness to parasite stimulation in vivo and in vitro. Adoptive transfer of L. amazonensis-specific Th1 cells prior to infection overcame the immune defects of the animals, leading to complete control of the disease. Studies with gene knockout mice suggested that IL-10, but not IL-4, contributed partially to compromised immunity in L. amazonensis-infected hosts. The data suggest that there is impairment in multiple immune functions at early stages of infection with L. amazonensis parasites and provide a compelling rationale to explore immune augmentation as an intervention in American cutaneous leishmaniasis.

Nitric oxide and cellular immunity in experimental cutaneous leishmaniasis

We examined the local and systemic production of nitric oxide (NO) and the pattern of cytokine during the course of Leishmania mexicana infection in susceptible BALB/c and resistant C57BL/6 mice. NO derivatives were measured in serum, and the expression of inducible nitric oxide synthase (iNOS), interferon (IFN-gamma), interleukin (IL-4) and epidermal Langerhans cells (LC) was measured in the lesions by immunohistology. Circulating NO concentrations, iNOS+ cell density, IFN-gamma+ Th1 cells and CD205+ Langerhans cells were higher in early lesions of resistant C57BL/6 mice. In contrast, susceptible BALB/c mice developed chronic and progressive lesions with a predominance of IL-4+ Th2 cells. In both susceptible and resistant mice, lesion size and lymph node volume followed a similar course. The early local and systemic production of NO in resistant mice may be related with the premature production of IFN-gamma observed, contributing to the resolution of the lesion.

Th2 responses predominate during the early phases of infection in patients with localized cutaneous leishmaniasis and precede the development of Th1 responses

Intralesional Th2 responses preceded the development of Th1 responses in localized cutaneous leishmaniasis due to Leishmania guyanensis. Although the number of parasites increased in Th2 lesions, no correlation was found between the levels of cytokine expression and the number of parasites. In contrast, the decreased number of parasites in Th1 lesions is negatively correlated to gamma interferon expression.

Development of a leishmaniasis vaccine: the importance of MPL

The parasite Leishmania has been used for pioneering work to define T-cell subsets and cytokine patterns mediating susceptibility or resistance to infectious pathogens. This understanding has been essential for the development of a new generation of candidate vaccines for major diseases, such as leishmaniases themselves, tuberculosis and others. It is clear that effective vaccines can be developed through a combination of both antigen and adjuvant selection. Until recently, no adjuvants acceptable for use in human T-cell vaccines were available. However, one such adjuvant, monophosphoryl lipid A, has been shown to be safe and effective. Just as the understanding of T-cell responses has been necessary for the development of a new generation of vaccines, an understanding of signaling by antigen-presenting cells has been essential for adjuvant selection. A combination of antigens and an adjuvant that is effective at promoting durable T-helper 1 responses and is safe for human use comprise a promising vaccine candidate, Leish-111f. This vaccine has potential application in both the prevention and treatment of leishmaniasis.

The site of cutaneous infection influences the immunological response and clinical outcome of hamsters infected with Leishmania panamensis

We determined that the site of inoculation (foot or snout) influences the clinical evolution and immune responses of hamsters infected with Leishmania (Viannia) panamensis. Hamsters infected in the snout showed (i) a more rapid and severe lesion evolution at multiple time points (P < 0.05), (ii) a more extensive inflammatory infiltrate and tissue necrosis, (iii) a higher tissue parasite burden, (iv) a higher antibody titre (P < 0.01), but lower antigen-specific spleen cell proliferative response (P = 0.02), and (v) a slower response to anti-leishmanial drug treatment (P < 0.002). In both inoculation groups there was co-expression of type 1 (IFN-gamma and IL-12) and some type 2 (IL-10 and TGF-beta, but not IL-4) cytokines in the cutaneous lesions and spleen. Early in the course of infection, hamsters infected in the snout showed higher expression of splenic IL-10 (P = 0.04) and intra-lesional IFN-gamma (P = 0.02) than foot infections. No expression of IL-12p40 or IL-4 was detected. During the chronic phase, snout lesions expressed more IFN-gamma (P = 0.001), IL-12p40 (P = 0.01), IL-10 (P = 0.009) and TGF-beta (P = 0.001), and the level of expression of each of these cytokines correlated with lesion size (P < or = 0.01). These results suggest that the site of infection influences the clinical outcome in experimental cutaneous leishmaniasis, and that the expression of macrophage-deactivating type 2 cytokines and/or an exaggerated type 1 proinflammatory cytokine response may contribute to lesion severity.

Vaccination against cutaneous leishmaniasis: current status

The different cutaneous leishmaniases are distinct in their etiology, epidemiology, transmission, and geographical distribution. In most instances cutaneous leishmaniasis is limited to one or a few skin ulcers that develop at the site where the parasites were deposited during the bite of the sandfly vector. Lesions typically heal spontaneously after several months but some lesions can be large and follow a chronic, more severe course. Protective immunity is usually acquired following cutaneous infection with Leishmania spp., so prevention of disease through prophylactic immunization appears to be feasible. Since vaccination with live, virulent parasites is associated with an unacceptable rate of adverse events, attention has turned to the use of killed or attenuated parasite vaccines and defined subunit vaccines. Whole parasite vaccines have the advantage of delivering multiple antigenic epitopes that may be necessary for initiation of a broad-based immune response. Persistent or repeated immune-stimulation by parasite antigens and/or sustained expression of interleukin-12 appear to be critical elements in the development of durable immunity. A number of purified or recombinant antigens, when co-administered with a vaccine adjuvant, appear promising as vaccine candidates against cutaneous leishmaniasis. The sustained expression of recombinant Leishmania antigens by vaccination with DNA is an attractive approach because it mimics the persistent antigenic stimulation of subclinical infection. Effective vaccine-induced immunity must generate an antigen-specific memory T cell population that, upon exposure to the infecting parasite, rapidly produces a type 1 effector T cell response that leads to interferon-gamma-mediated activation of infected macrophages to kill the intracellular parasites. This parasite-directed recall response must be prompt and of sufficient magnitude to overcome the subversive effect that the intracellular infection has on macrophage effector function. It is unlikely that vaccination against cutaneous leishmaniasis would induce sterile immunity, but a small number of parasites are likely to persist subclinically.

Up-regulation of Th1-type responses in mucosal leishmaniasis patients

The cytokine profile produced by peripheral blood mononuclear cells (PBMC) in response to leishmania antigens and the ability of interleukin-10 (IL-10) and transforming growth factor beta (TGF-beta) to modulate the immune response were evaluated in 21 mucosal leishmaniasis patients. Patients with mucosal disease exhibited increased gamma interferon (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) secretion and decreased IL-10 secretion compared to patients with classical cutaneous leishmaniasis. CD4(+) Th1 cells were the main source of IFN-gamma and TNF-alpha production in mucosal leishmaniasis patients. Evaluation of cytokine gene expression in PBMC of these patients showed that there was strong up-regulation of IFN-gamma transcripts upon stimulation with leishmania antigen, in contrast to the baseline levels of IL-10 mRNA. IL-10 suppressed IFN-gamma production by 48% in cell cultures from cutaneous leishmaniasis patients and by 86% in cell cultures from healthy subjects stimulated with purified protein derivative, whereas in similar conditions IL-10 suppressed IFN-gamma production by 19% in cell cultures from mucosal leishmaniasis patients stimulated with leishmania antigen. TGF-beta suppressed IFN-gamma levels to a greater extent in healthy subjects than in mucosal leishmaniasis and cutaneous leishmaniasis patients. These data indicate that a poorly modulated T-cell response in mucosal leishmaniasis patients leads to production of high levels of proinflammatory cytokines, such as IFN-gamma and TNF-alpha, as well as a decreased ability of IL-10 and TGF-beta to modulate this response. These abnormalities may be the basis for the pathological findings observed in this disease.

B-cell infiltration and frequency of cytokine producing cells differ between localized and disseminated human cutaneous leishmaniases

Biopsies from human localized cutaneous lesions (LCL n = 7) or disseminated lesions (DL n = 8) cases were characterized according to cellular infiltration,frequency of cytokine (IFN-gamma, TNF-alpha) or iNOS enzyme producing cells. LCL, the most usual form of the disease with usually one or two lesions, exhibits extensive tissue damage. DL is a rare form with widespread lesions throughout the body; exhibiting poor parasite containment but less tissue damage. We demonstrated that LCL lesions exhibit higher frequency of B lymphocytes and a higher intensity of IFN-gamma expression. In both forms of the disease CD8+ were found in higher frequency than CD4+ T cells. Frequency of TNF-alpha and iNOS producing cells, as well as the frequency of CD68+ macrophages, did not differ between LCL and DL. Our findings reinforce the link between an efficient control of parasite and tissue damage, implicating higher frequency of IFN-gamma producing cells, as well as its possible counteraction by infiltrated B cells and hence possible humoral immune response in situ.

Endemically exposed asymptomatic individuals show no increase in the specific Leishmania (Viannia) panamensis-Th1 immune response in comparison to patients with localized cutaneous leishmaniasis

In Colombia, most cases of human cutaneous leishmaniasis are caused by Leishmania (Viannia) panamensis. Interestingly, up to 30% of the exposed population do not suffer from clinical leishmaniasis although it is likely that they are continuously infected with Leishmania parasites. Since it is believed that the induction of efficient Th1 immune responses protects against Leishmania infections both in humans and in animal models, we determined if endemically exposed asymptomatics showed stronger Leishmania-specific Th1 immune responses than patients with active localized cutaneous leishmaniasis (LCL). We found that Montenegro skin test responses were slightly higher among asymptomatic individuals compared to patients suffering from LCL. However, PBMC from patients with LCL showed similar Leishmania-specific proliferative responses compared to PBMC from asymptomatic individuals. Furthermore, PBMC from both groups also secreted similar amounts of IFN-gamma, IL-12p40 and IL-10 after in vitro exposure to L. panamensis. No IL-4 was detected in the supernatants. Taken together our results suggest that lack of LCL development in endemically exposed asymptomatics cannot be explained by stronger systemic anti-Leishmania Th1 immune responses or decreased Th2 responses in these individuals in comparison to individuals who develop LCL. It may be possible that other mechanisms are responsible for resistance to cutaneous leishmaniasis in Colombia in endemically exposed asymptomatics.

Expression of inducible nitric oxide synthase in skin lesions of patients with american cutaneous leishmaniasis

Cytokine-inducible (or type 2) nitric oxide synthase (iNOS) is indispensable for the resolution of Leishmania major or Leishmania donovani infections in mice. In contrast, little is known about the expression and function of iNOS in human leishmaniasis. Here, we show by immunohistological analysis of skin biopsies from Mexican patients with local (LCL) or diffuse (DCL) cutaneous leishmaniasis that the expression of iNOS was most prominent in LCL lesions with small numbers of parasites whereas lesions with a high parasite burden (LCL or DCL) contained considerably fewer iNOS-positive cells. This is the first study to suggest an antileishmanial function of iNOS in human Leishmania infections in vivo.

Divergent expression of inflammatory dermal chemokines in cutaneous leishmaniasis

Human leishmaniasis is caused by protozoan Leishmania (L.) parasites and comprises a heterogeneous group of clinical appearances ranging from visceral to cutaneous leishmaniasis. In the New World, L. mexicana mediates American cutaneous leishmaniasis, one of the most common forms of this disease. Two different disease progressions can be observed: (i) self-healing localized cutaneous leishmaniasis (LCL) and (ii) progressive diffuse cutaneous leishmaniasis (DCL). These different forms are associated with a T helper 1 (Th1) or Th2 response, respectively, and are additionally characterized by opposing dermal chemokine profiles. Lesions of LCL show high expression of CCL2/MCP-1, CXCL9/MIG, CXCL10/IP-10 and only low amounts of CCL3/MIP-1alpha. In contrast, lesions of chronic DCL are dominated by the expression of CCL3/MIP-1alpha. This finding implies that CCL2/MCP-1 contributes to the healing process. Indeed, CCL2/MCP-1 induces leishmanicidal activities in human monocytes in contrast to CCL3/MIP-1alpha. This effect is enhanced by interferon-gamma and abrogated by interleukin-4. In the murine model of leishmaniasis, the impact of CCL2/MCP-1 is well documented. Normally resistant mice become susceptible for Leishmania infections if CCR2, the receptor for CCL2/MCP-1, is knocked out. Based on this evidence, we propose that tissue specific expression of these small molecules actively regulates cell traffic and tissue localization of effector cells and, additionally, has direct immunological effects.

Cytokine gene expression and protein production in peripheral blood mononuclear cells of children with acute dengue virus infections

Plasma leakage in dengue hemorrhagic fever (DHF) is associated with elevated plasma levels of cytokines. To define further the contribution of immune activation to DHF and the source of cytokines, we analyzed the production of cytokines in peripheral blood mononuclear cells (PBMC) obtained from children with dengue, using RT-PCR and immunostaining. Tumor necrosis factor-alpha (TNF-alpha) and TNF-beta expression was detected in all samples by PCR and in < 50% of samples by immunostaining. Interferon-gamma (IFN-gamma) expression was detected in < 50% of samples by either method. Interleukin-2 (IL-2) and IL-4 expression was detected in a few samples by immunostaining but was not detectable by PCR. We found greater expression of TNF-alpha and IL-4 in DHF than in dengue fever or other (non-dengue) febrile illnesses. These results support the model of immunopathogenesis of DHF. However, low levels of cytokine expression in PBMC suggest that cellular activation in tissues may contribute to high serum cytokine levels in DHF.

Gender is a major determinant of the clinical evolution and immune response in hamsters infected with Leishmania spp

In regions where leishmaniasis is endemic, clinical disease is usually reported more frequently among males than females. This difference could be due to disparate risks of exposure of males and females, but gender-related differences in the host response to infection may also play a role. Experimental studies of the influence of gender on Leishmania infection have not included parasites of the subgenus Viannia, which is the most common cause of cutaneous leishmaniasis in the Americas. Mice are not readily susceptible to infection by Leishmania (Viannia) spp., but cutaneous infection of hamsters with L. (V.) panamensis or L. (V.) guyanensis resulted in chronic lesions typical of the human disease caused by these parasites. Strikingly, infection of male hamsters resulted in significantly greater lesion size and severity, an increased rate of dissemination to distant cutaneous sites, and a greater parasite burden in the draining lymph node than infection in female animals. Two lines of evidence indicated this gender-related difference in disease evolution was determined at least in part by the sex hormone status of the animal. First, prepubertal male animals had smaller and/or less severe cutaneous lesions than adult male animals. Second, infection of testosterone-treated female animals resulted in significantly larger lesions than in untreated female animals. The increased severity of disease in male compared to female animals was associated with significantly greater intralesional expression of interleukin-4 (IL-4) (P = 0.04), IL-10 (P = 0.04), and transforming growth factor beta (TGF-beta) (P < 0.001), cytokines known to promote disease in experimental leishmaniasis. There was a direct correlation between the expression of TGF-beta mRNA and lesion size (Spearman's correlation coefficient = 0.873; P < 0.001). These findings demonstrate an inherent risk of increased disease severity in male animals, which is associated with a more permissive immune response.

HLA-B27-transfected (Salmonella permissive) and HLA-A2-transfected (Salmonella nonpermissive) human monocytic U937 cells differ in their production of cytokines

The cytokine secretion of the Salmonella-permissive, HLA-B27-positive U937 cells was examined, as it was previously shown that these cells kill Salmonella less efficiently than controls. Salmonella-permissive U937 cells showed upregulated production of interleukin 10 and to a lesser extent tumor necrosis factor alpha. HLA-B27-associated modulation of cytokine responses may have importance in the pathogenesis of reactive arthritis.

Immunoglobulin E antileishmanial antibody response in cutaneous leishmaniasis

High levels of antileishmanial immunoglobulin E (IgE) antibodies are associated with disease activity in visceral leishmaniasis. Herein, we report our observations about the relationship between antileishmanial IgE antibodies and clinical aspects of cutaneous leishmaniasis. This study was carried out with 45 patients (29 male and 16 female), with ages ranging from 11 to 48 years. All subjects were from an area to which leishmaniasis is endemic, Corte de Pedra (Bahia, Brazil), and the duration of the illness was </=30 days. The patients were classified as positive or negative for IgE serology in enzyme-linked immunosorbent assay with leishmanial antigens. IgE antibodies were detected in 18 patients (optical density, 0.421 +/- 0.30; 95% confidence interval, 0.27 to 0.57), and only 3 (17%) had more than one ulcer. In this group the diameter of Montenegro's reaction was 18 +/- 12.2 mm. In the group with negative IgE serology, 11 of 27 patients (48%) presented two or more cutaneous ulcers, and the mean of the skin test result was 9 +/- 6.9 mm. There was a positive correlation between IgE antibody levels and Montenegro's reaction size and an inverse correlation between IgE antileishmanial antibodies and the number of skin ulcers. The presence of antileishmanial IgE antibodies in cutaneous leishmaniasis may be a result of immunoregulatory events with clinical implications.

Genetic epidemiology of visceral leishmaniasis in northeastern Brazil

Familial clustering of disease, racial differences in asymptomatic:disease ratios, and studies of mice all point to a genetic component for disease susceptibility in visceral leishmaniasis. Analysis of 87 multi-case pedigrees (824 individuals; 138 nuclear families) from a region of northeastern Brazil endemic for Leishmania chagasi demonstrates a high relative risk ratio (lambda(2S) = 34) to further siblings of affected sibling pairs. Complex segregation analysis using POINTER and COMDS show that all single locus models, as well as polygenic and multifactorial models, provide a significantly (P < 0.001) better fit to the data than a sporadic model. Of the genetic models, the general single locus model was not significantly different from additive or dominant single locus models, all of which gave a gene frequency for the putative disease susceptibility allele of approximately 0.002. The general single locus model was strongly favored (P < 0.001) over a recessive single gene model. Using POINTER, polygenic and multifactorial models were clearly rejected (P < 0.001 in all cases) in favor of the general single locus model. Using COMDS, the analysis was extended to consider two locus models. Results under a general two-locus model did not differ significantly from the dominant, additive, or general single locus models. Under this model, one locus was estimated at a gene frequency of 0.0017, i.e., in the same range as the disease susceptibility locus for the most favored single gene models, with the second locus at a much lower frequency of 0.0002. Hence, the data support the hypothesis that a single major gene may be important in determining disease susceptibility in this population. To identify the gene(s) involved, a genome scan with replication using two subsets of these larger pedigrees with power to detect linkage is in progress.

Intralesional isotype profiles in human localized cutaneous leishmaniasis lesions

This immunocytochemical study evaluates the presence of IgG1-4, IgA and IgE immunoglobulins in active lesions of 25 localized cutaneous leishmaniasis patients from three bioclimatic areas (Awa, Afa and Bsha) in Mérida State, Venezuela. All immunoglobulin isotypes except IgE were detected, with variable intensity, in one or more of the epidermal or dermal components of skin lesions. IgG1 and IgG2 were detected significantly more frequently than IgG3, IgG4 and IgA. The ranking of the isotypes according to frequency of detection was the same in all areas: IgG1 = IgG2 > IgG3 = IgG4 = IgA, but considered as whole, all isotypes were detected significantly more frequently in patients from the Awa area than in those from the Bsha area. The predominant expression of isotypes IgG1 and IgG2 suggests a preferential Th1 like immune response. Anti-Leishmania immunoserum stained only parasites and their debris, suggesting that most of the immunostaining was nonspecific.

Different Leishmania species determine distinct profiles of immune and histopathological responses in CBA mice

Most experimental studies on leishmaniasis compare two different inbred strains of mice that are resistant or susceptible to one species of Leishmania. In the present study we characterized some cytokines and nitric oxide production as well as histological changes related to resistance and susceptibility in isogenic CBA mice infected with Leishmania major or Leishmania amazonensis. CBA mice are capable of controlling infection with L. major, but they succumb to infection with L. amazonensis. Cells from susceptible L. amazonensis-infected CBA mice produced interleukin (IL)-4 and IL-10 but no interferon (IFN)-gamma. On the other hand, resistant L. major-infected CBA mice produced IFN-gamma and IL-10, but IL-4 was detected only in the first week of infection. Histopathological studies showed patterns of tissue responses at the site of the infection and in the draining lymph nodes that correlated with resistance or susceptibility. Resistant mice showed a mixed inflammatory cell infiltration and granulomas in the lesions, whereas in susceptible mice only heavily parasitized macrophages were seen. Our results indicate an important role of the parasite species in determining the pattern of immune response. L. amazonensis induces a Th2-type immune response, whereas L. major induces a Th1-type response. These factors must be identified and taken into account in the strategies for the development of vaccines against leishmaniasis. The model presented here will be useful for the study of such factors.

Frequent exposure of mice to crude Brucella abortus proteins down-regulates immune response

Mice repeatedly immunized via the intraperitoneal route with a Brucella abortus antigen lost their ability to develop a strong in vitro lymphoproliferative response. This result correlates with a decreased tendency of the lymphoid population to produce interferon-gamma when stimulated in culture with the immunizing antigen. With respect to the humoral response, as the number of immunizations increased, the animals produced more specific immunoglobulin M and immunoglobulin G1 antibodies. It is postulated that the long-term exposure of an animal to Brucella antigen changes the nature of the immune response from a T-cell-mediated response to a humoral response favouring the establishment of the disease.

Monocyte chemotactic protein-1 stimulates the killing of leishmania major by human monocytes, acts synergistically with IFN-gamma and is antagonized by IL-4

We recently demonstrated that monocyte chemotactic protein-1 (MCP-1) is strongly expressed in lesions of patients with self-healing localized cutaneous leishmaniasis (LCL) whereas it is scarce in those of chronic diffuse cutaneous leishmaniasis (DCL). This finding indicated that MCP-1 may contribute to the healing process. In the present study, we analyzed the capacity of MCP-1 to trigger leishmanicidal activities. The results show that MCP-1 directly stimulates the elimination of intracellular Leishmania parasites by human monocytes, a potential that correlates with the induction of reactive oxygen intermediates. Release of NO was not detected. To understand the cross-talk between the chemokine and T cell-associated cytokines, we studied the influence of the Th1 cytokine IFN-gamma and the Th2 cytokine IL-4 on MCP-1-mediated activation of human monocytes. The data demonstrate that IFN-gamma and MCP-1 synergistically activate monocytes to clear intracellular parasites, whereas IL-4 abrogates the effect of MCP-1. Furthermore, IL-4 inhibits MCP-1 expression by infected monocytes, a finding that may explain the lack of MCP-1 in chronic lesions. The data suggest a novel model for macrophage activation in cutaneous leishmaniasis. In lesions of LCL, the synergistic action of MCP-1 and IFN-gamma may stimulate the killing of parasites by macrophages and promote healing, whereas the presence of IL-4 in DCL lesions may favor the suppression of MCP-1 and, together with the lack of IFN-gamma, the progression of disease.

Immunotherapy with live BCG plus heat killed Leishmania induces a T helper 1-like response in American cutaneous leishmaniasis patients

Previous work has shown that American cutaneous leishmaniasis (ACL) patients treated with viable BCG plus heat killed promastigotes of Leishmania amazonensis show the same rate of cure as patients receiving conventional chemotherapy. The treatment is safe and economical, but the immunological correlates of cure have not been examined. In the present study, T cell responses have been analysed in 43 ACL patients, including patient groups sampled before and after therapy, and in 10 endemic controls. Lymphocyte proliferation, interferon (IFN)-gamma and interleukin (IL)-5 responses to crude antigen (L. amazonensis, MEL; Mycobacterium tuberculosis PPD; M. bovis BCG) stimulation, and serum IL-5 levels, were analysed. In endemic volunteers, proliferative responses to BCG were high and IFN-gamma responses low. In contrast, localized cutaneous (LCL) and mucocutaneous (MCL) patients showed low proliferative and high IFN-gamma responses to BCG. Treatment enhanced the IFN-gamma response and further decreased the proliferative response to BCG, especially in MCL patients. LCL and MCL patients showed an increase in proliferative and IFN-gamma responses to MEL with treatment, but the response was not exaggerated in MCL patients, either before or after treatment, compared to LCL patients. IL-5 production was low in T cell assays, and > 62% of untreated patients had very low serum IL-5 levels. There were no significant changes in serum IL-5 with treatment. Overall results show enhanced antigen-specific IFN-gamma responses to the two components of the immunotherapy, live M. bovis BCG and heat killed L. amazonensis, which is consistent with a shift in balance of T cell response towards a T helper 1 response and clinical cure mediated by IFN-gamma.

Mucosal leishmaniasis: quantitative nasal cytology as a marker of disease activity and indicator of healing

Mucosal leishmaniasis (ML) follow-up is based on subjective parameters. Using simplified quantitative cytology of nasal lavages (QNCs), we studied 20 ML patients, 10 patients with cutaneous leishmaniasis (CL), and 10 healthy subjects. Patients with ML were treated with antimony and followed up with otolaryngological examination plus QNCs for 6 months. At the first evaluation, the median total number of cells in ML patients (1,540,000) was greater than that in CL patients (215,000) or that in healthy subjects (250,000). Neutrophils were predominant in ML patients, in contrast to both sets of controls, in whom epithelial cells were more frequent. During treatment, we found a significant reduction in total nasal cell counts in ML patients who were cured, and encountered a switch in predominant cell type. The cytology of 2 patients who did not respond to antimony remained the same. It is therefore possible to detect nasal inflammation in ML patients through QNCs, which may indicate extension of mucosal involvement, providing an objective parameter to monitor therapy.

The humoral immune response to the kinetoplastid membrane protein-11 in patients with American leishmaniasis and Chagas disease: prevalence of IgG subclasses and mapping of epitopes

The kinetoplastid membrane protein-11 (KMP-11) is a major target of the humoral immune response during Leishmania-infections. The majority of sera from visceral leishmaniasis, mucocutaneous leishmaniasis and even some cutaneous leishmaniasis patients contain detectable IgG antibodies against KMP-11. We also provide evidence that this protein may act as a potent antigen in T. cruzi infections, since most Chagas sera show immunological cross-reactivity. Therefore, KMP-11 cannot be used as a specific diagnostical tool for the serodiagnosis of leishmaniasis in those regions where both, Leishmania and T. cruzi infections overlap geographically. When analyzing the subclass specificity of the antibody response to KMP-11 we observed the following order of reactivity: IgG1 > > IgG3 > IgG2 > IgG4, which is similiar to that seen in crude parasite extract. The mapping of antigenic determinants by using synthetic 20-mer peptides revealed the existence of predominantly conformational epitopes in leishmaniasis, while 50% of sera from Chagas patients reacted with a particular KMP-11 peptide. These results therefore suggest the presence of disease-specific B-cell epitopes.

Modulation of peripheral blood mononuclear cell activation status during Salmonella-triggered reactive arthritis

OBJECTIVE

To determine the activation status of mononuclear cells in the peripheral circulation during the acute phase and the recovery phase of Salmonella-triggered reactive arthritis (ReA).

METHODS

Peripheral blood mononuclear cells (PBMC) were obtained from 8 patients with Salmonella infection (4 with ReA and 4 without) and were studied by reverse transcription-polymerase chain reaction for messenger RNA (mRNA) of proinflammatory and antiinflammatory cytokines, by flow cytometry (FC) for cell surface activation and adhesion molecules, by immunofluorescence (IF) microscopy for bacterial antigens, and by FC, IF, and DNA fragmentation on gel for signs of apoptosis.

RESULTS

During the acute phase of the infection, PBMC were activated in all patients, as characterized by high levels of expression of CD14, CD11b, and CD11c on monocytes. In the patients with ReA, PBMC also had the capacity to produce interleukin-1beta (IL-1beta), IL-6, IL-8, IL-10, and tumor necrosis factor alpha. During the amelioration of disease, monocyte activation was decreased in all patients. A complete down-regulation of CD14 was detected only in the patients with ReA, whereas the expression of CD14 in the patients without ReA was positive and was similar to that in healthy controls. In addition, cytokine mRNA levels decreased regardless of the presence of Salmonella antigens in blood cells in all 4 patients with ReA.

CONCLUSION

High levels of expression of some activation and adhesion molecules and elevated levels of mRNA for certain cytokines that are predominantly produced by monocytes were found in PBMC from patients with acute Salmonella-triggered ReA, which suggests that these cells are activated. On the other hand, complete down-regulation of CD14 and a marked decrease in the cytokine production capacity during amelioration of the disease suggest that suppression of PBMC activity might be involved in recovery from ReA.

Protection of C57BL/10 mice by vaccination with association of purified proteins from Leishmania (Leishmania) amazonensis

In the past few years, induction of protective immunity to cutaneous leishmaniasis has been attempted by many researchers using a variety of antigenic preparations, such as living promastigotes or promastigote extracts, partially purified, or defined proteins. In this study, eleven proteins from Leishmania (Leishmania) amazonensis (LLa) with estimated molecular mass ranging from 97 to 13.5kDa were isolated by polyacrylamide gel electrophoresis and electro-elution. The proteins were associated as vaccine in different preparations with gp63 and BCG (Bacilli Calmette-Guérin). The antigenicity of these vaccines was measured by their ability to induce the production of IFN-gamma by lymphocyte from subjects vaccinated with Leishvacinregister mark or target. The immunogenicity was evaluated in vaccinated mice. C57BL/10 mice were vaccinated with three doses of each vaccine consisting of 30 microg of each protein at 15 days interval. One hundred microg of live BCG was only used in the first dose. Seven days after the last dose, they received a first challenge infection with 10(5) infective promastigotes and four months later, a second challenge was done. Two months after the second challenge, 42.86% of protection was obtained in the group of mice vaccinated with association of proteins of gp63+46+22kDa, gp63+13.5+25+42kDa, gp63+46+42kDa, gp63+66kDa, and gp63+97kDa; 57. 14% of protection was demonstrated with gp63+46+97+13.5kDa, gp63+46+97kDa, gp63+46+33kDa, and 71.43% protection for gp63 plus all proteins. The vaccine of gp63+46+40kDa that did not protect the mice, despite the good specific stimulation of lymphocytes (LSI = 7. 60) and 10.77UI/ml of IFN-gamma production. When crude extract of L. (L.) amazonensis was used with BCG a 57.14% of protection was found after the first challenge and 28.57% after the second, the same result was observed for gp63. The data obtained with the vaccines can suggest that the future vaccine probably have to contain, except the 40kDa, a cocktail of proteins that would protect mice against cutaneous leishmaniasis.

Immunoglobulin subclass distribution and diagnostic value of Leishmania donovani antigen-specific immunoglobulin G3 in Indian kala-azar patients

Visceral leishmaniasis, or kala-azar, a fatal tropical disease, remains problematic, as early diagnosis is difficult and treatment often results in drug resistance and relapse. We have developed a sensitive enzyme-linked immunosorbent assay (ELISA), using leishmanial membrane antigenic extracts (LAg) to detect specific antibody responses in 25 untreated Indian visceral leishmaniasis patients. To investigate the pathogenetic significance of isotype markers in kala-azar, relative levels of specific immunoglobulin G (IgG), IgM, IgA, IgE, and IgG subclasses were analyzed under clinically established diseased conditions. Since LAg showed higher sensitivity for specific IgG than lysate, the immunoglobulin isotype responses were evaluated, with LAg as antigen. Compared to 60 controls, which included patients with malaria, tuberculosis, leprosy, and typhoid and healthy subjects, visceral leishmaniasis patients showed significantly higher IgG (100% sensitivity, 85% specificity), IgM (48% sensitivity, 100% specificity), and IgE (44% sensitivity, 98.3% specificity) responses. Low levels of IgA in visceral leishmaniasis patients contrasted with a 13-fold-higher reactivity in sera from patients with leprosy. Among IgG subclasses, IgG1, -3, and -4 responses were significantly higher in visceral leishmaniasis patients than in the controls. IgG2 response, however, was significantly higher (twofold) in leprosy than even visceral leishmaniasis patients. The rank orders for sensitivity (IgG = IgG1 = IgG3 = IgG4 > IgG2 > IgM > IgE > IgA) and specificity (IgM = IgG3 > IgE > IgG4 > IgG2 > IgG > IgG1 > IgA) for LAg-specific antibody responses suggest the potentiality of IgG3 as a diagnostic marker for visceral leishmaniasis.

The United States military and leishmaniasis

Leishmaniasis occurs not only in American travelers and military personnel alike but infects a significant portion of the world's population. The US military has made major contributions to the understanding of the complicated epidemiology of this parasite, the development of rapid reliable diagnostic tests, and to the development of safe, more efficient, and more effective treatment of leishmaniasis.