The major circulating immunosuppressive activity in American visceral leishmaniasis patients is associated with a high-molecular weight fraction and is not mediated by IgG, IgG immune complexes or lipoproteins

Opportunistic infections, due to disease-related immunosuppression, constitute the major cause of death in American visceral leishmaniasis (AVL). Sera from these patients (AVL sera) non-specifically inhibit the in vitro proliferative response of normal human lymphocytes to lectins or antigens. In the present work, the mediation of this inhibition by IgG, immune complexes and low- or very low-density lipoproteins was studied. AVL serum fractions containing proteins with the molecular weight of IgG, and IgG, purified from AVL sera by anion exchange chromatography, did not suppress the lymphoproliferation. Most of the suppressive activity of AVL sera was associated with a fraction containing molecules with molecular weights above 430 kDa. This would be compatible with it being due to immune complexes and/or lipoproteins, and not to soluble IL-2 receptors as reported previously. However, neither of the two possibilities seem to be the case, as (1) depletion of immune complexes by protein-A followed by protein-G chromatographies did not affect the serum suppressive activity, (2) no correlation between immune complex contents and suppressive activities in individual sera was observed, and (3) plasma lipoproteins (VLDL and LDL), purified from AVL patients and from healthy individuals, had the same degree of immunosuppressive activity.

Mucosal Leishmaniasis Patients Display an Activated Inflammatory T-cell Phenotype Associated with a Nonbalanced Monocyte Population

Leishmania braziliensis is a parasite that can induce at least two clinical forms of leishmaniasis in humans: cutaneous leishmaniasis (CL) and mucosal leishmaniasis (ML). In humans, the specific mechanisms that determine which form will develop following infection are not well established. In this study, peripheral blood mononuclear cells from 17 CL and 9 ml patients were compared both ex vivo and after culture with soluble leishmania antigen (SLA). Patients with ML presented a higher frequency of activated T cells as measured by ex vivo frequencies of (CD4+)(CD69+), (CD4+)(CD28-), (CD4+)(CD62L-) and (CD8+)(CD69+) than those with CL. Moreover, after stimulation with SLA, patients with ML presented a higher frequency of TNF-alpha-producing CD4+ and CD14+ cells than CL individuals. While CL patients displayed a positive correlation between the frequency of IL-10 and TNF-alpha-producing monocytes, the ML patients did not. This lack of a positive correlation between IL-10-producing and TNF-alpha-producing monocytes in ML patients could lead to a less controlled inflammatory response in vivo. These results corroborate with a model of an exacerbated, unregulated, immune response in ML patients and point to key immunomodulatory leucocyte populations and cytokine networks that may be involved in the development of immunopathology in ML patients.

Identification of paramyosin T cell epitopes associated with human resistance to Schistosoma mansoni reinfection

Paramyosin, a Schistosoma mansoni myoprotein associated with human resistance to infection and reinfection, is a candidate antigen to compose a subunit vaccine against schistosomiasis. In this study, 11 paramyosin peptides selected by TEPITOPE algorithm as promiscuous epitopes were produced synthetically and tested in proliferation and in vitro human leucocyte antigen (HLA)-DR binding assays. A differential proliferative response was observed in individuals resistant to reinfection compared to individuals susceptible to reinfection in response to Para (210-226) peptide stimulation. In addition, this peptide was able to bind to all HLA-DR molecules tested in HLA-DR binding assays, confirming its promiscuity. Para (6-22) and Para (355-371) were also shown to be promiscuous peptides, because they were able to bind to the six and eight most prevalent HLA-DR alleles used in HLA-DR binding assays, respectively, and were also recognized by T cells of the individuals studied. These results suggest that these paramyosin peptides are promising antigens to compose an anti-schistosomiasis vaccine.

Prostanoids modulate inflammation and alloimmune responses during graft rejection

Acute rejection of a transplanted organ is characterized by intense inflammation within the graft. Yet, for many years transplant researchers have overlooked the role of classic mediators of inflammation such as prostaglandins and thromboxane (prostanoids) in alloimmune responses. It has been demonstrated that local production of prostanoids within the allograft is increased during an episode of acute rejection and that these molecules are able to interfere with graft function by modulating vascular tone, capillary permeability, and platelet aggregation. Experimental data also suggest that prostanoids may participate in alloimmune responses by directly modulating T lymphocyte and antigen-presenting cell function. In the present paper, we provide a brief overview of the alloimmune response, of prostanoid biology, and discuss the available evidence for the role of prostaglandin E2 and thromboxane A2 in graft rejection.

Recombinant leishmania antigens for serodiagnosis of visceral leishmaniasis

Serological tests with crude or recombinant Leishmania antigens are important tools for the diagnosis of leishmania infection. However, these tests are not markers of active visceral leishmaniasis (VL), since antibodies to these markers are often observed in individuals with subclinical L. chagasi infection and they do not fall shortly after therapy. In this study, levels of immunoglobulin G (IgG) against three recombinant Leishmania antigens (rH2A, KMP11, and the "Q" protein) were evaluated in sera from individuals with subclinical L. chagasi infection and in patients with VL pre- and posttherapy. The sensitivity of the serological test for diagnosis of VL was 100% with all three antigens. The titers of IgG fell significantly after therapy. While most of the individuals with subclinical L. chagasi infection had antibodies to rH2A and the "Q" protein, only 1 out of 15 individuals had antibodies to KMP11. These data indicate that KMP11 may be used to discriminate L. chagasi infection from active VL and may serve as a marker of response to therapy.

Association between atopy and recurrent vaginal candidiasis

To determine whether there is an association between atopy and recurrent vaginal candidiasis (RVC) and to evaluate the type-2 immune response in patients with RVC. Evaluation of immediate hypersensitivity skin tests to aeroallergens, measurement of total IgE and Candida albicans specific IgE and levels of IL-5 in 44 women with RVC and 26 with sporadic vaginal candidiasis (SVC). Statistical analyses were performed by Mann-Whitney test and chi(2) test with Yates correction. History of atopy (68%) and positive skin test (42%) were higher (P < 0.05) in RVC than in patients with SVC. No significant difference was found in total IgE, C. albicans specific IgE and IL-5 levels. There was a strong association between atopy and RVC, but type-2 immune response to C. albicans antigen was absent or similar in the two groups of patients.

Epidemiological and clinical interaction between HTLV-1 and Strongyloides stercoralis

Strongyloides stercoralis is the most common human parasitic nematode that is able to complete a life cycle and proliferate within its host. The majority of patients with strongyloidiasis have an asymptomatic infection or mild disease. However, when autoinfection occurs, a high number of infecting larvae can gain access to the bloodstream by penetrating the colonic mucosa leading to a severe hyperinfection and the development of disseminated strongyloidiasis. The human T cell lymphotropic virus type 1 (HTLV-1) predominantly infects T cells and induces spontaneous lymphocyte proliferation and secretion of high levels of type 1 cytokines. Strongyloides stercoralis patients with HTLV-1 co-infection have a modified immunological responses against parasite antigens and co-infection has clinical implications for strongyloidiasis. The high production of IFN-gamma observed in patients co-infected with HTLV-1 and Strongyloides stercoralis decreases the production of IL-4, IL-5, IL-13 and IgE, molecules that participate in the host defence mechanism against helminths. Moreover, there is a decrease in the efficacy of treatment of Strongyloides stercoralis in patients co-infected with HTLV-1. Alterations in the immune response against Strongyloides stercoralis and the decrease in the efficacy of anti-parasitic drugs are responsible for the increased prevalence of Strongyloides stercoralis among HTLV-1 infected subjects and make HTLV-1 infection the most important risk factor for disseminated strongyloidiasis.

Effect of LACK and KMP11 on IFN-gamma Production by Peripheral Blood Mononuclear Cells from Cutaneous and Mucosal Leishmaniasis Patients

The immune modulatory properties of recombinant antigens Kinetoplasmid membrane protein-11 (KMP11) and Leishmania homologue of receptors for activated C kinase (LACK) in cutaneous leishmaniasis (CL) and mucosal leishmaniasis (ML) patients were evaluated. The mean levels of interferon-gamma (IFN-gamma) in soluble leishmania antigen (SLA) stimulated peripheral blood mononuclear cells (PBMC) of ML and CL patients were 5625 +/- 2333 pg/ml and 4422 +/- 3665 pg/ml, respectively. IFN-gamma was not detected in cultures stimulated with KMP11 or LACK. Interleukin-10 (IL-10) concentration in SLA, KMP11 and LACK-stimulated PBMC of ML patients was 13 +/- 12 pg/ml, 285 +/- 388 pg/ml and 802 +/- 483 pg/ml, respectively. Addition of KMP11 or LACK to SLA-stimulated PBMC of CL and ML patients enhanced IL-10 production (P < 0.05). Addition of KMP11 decreased IFN-gamma levels by 52% in CL patients and by 19% in ML patients. Addition of LACK to SLA-stimulated cultures decreased IFN-gamma levels by 58% in CL patients and by 30% in ML patients. Neutralization of IL-10 abrogated the downregulatory effect of LACK and KMP11. The modulatory properties of LACK and KMP11 are due to induction of IL-10 production and may be helpful for attenuating chronic inflammatory diseases. However, in some clinical conditions, as demonstrated for ML, these molecules are not able to suppress the IFN-gamma response, even inducing IL-10 production.

Long-term ethanol intoxication reduces inflammatory responses in rats

The anti-inflammatory effects of long-term ethanol intoxication were determined during ethanol treatment and withdrawal on the basis of neutrophil and eosinophil migration, hind paw edema and mast cell degranulation. Male Wistar rats (180-200 g, around 2 months of age) were exposed to increasing concentrations of ethanol vapor over a 10-day period. One group was evaluated immediately after exposure (treated group - intoxicated), and another was studied 7 h later (withdrawal group). Ethanol inhalation treatment significantly inhibited carrageenan--(62% for the intoxicated group, N = 5, and 35% for the withdrawal group, N = 6) and dextran-induced paw edema (32% for intoxicated rats and 26% for withdrawal rats, N = 5 per group). Ethanol inhalation significantly reduced carrageenan-induced neutrophil migration (95% for intoxicated rats and 41% for withdrawn rats, N = 6 per group) into a subcutaneous 6-day-old air pouch, and Sephadex-induced eosinophil migration to the rat peritoneal cavity (100% for intoxicated rats and 64% for withdrawn rats, N = 6 per group). A significant decrease of mast cell degranulation was also demonstrated (control, 82%; intoxicated, 49%; withdrawn, 51%, N = 6, 6 and 8, respectively). Total leukocyte and neutrophil counts in venous blood increased significantly during the 10 days of ethanol inhalation (leukocytes, 13, 27 and 40%; neutrophils, 42, 238 and 252%, respectively, on days 5, 9 and 10, N = 7, 6 and 6). The cell counts decreased during withdrawal, but were still significantly elevated (leukocytes, 10%; neutrophils, 246%, N = 6). These findings indicate that both the cellular and vascular components of the inflammatory response are compromised by long-term ethanol intoxication and remain reduced during the withdrawal period.

Antileishmanial IgG and IgE antibodies recognize predominantly carbohydrate epitopes of glycosylated antigens in visceral leishmaniasis

The specificity of human antileishmanial IgG and IgE antibodies to glycosylated antigens of Leishmania chagasi was evaluated. An ELISA was performed with soluble leishmanial antigen (SLA) and a panel of 95 sera including samples from patients with subclinical infection (SC) and visceral leishmaniasis (VL), subjects cured of visceral leishmaniasis (CVL), and from healthy individuals from endemic areas (HIEA). Antileishmanial IgG were verified for 18 (40%) of 45 SC subjects (mean absorbance of 0.49 +/- 0.17). All nine sera from VL patients had such antibody (0.99 +/- 0.21), while 11 (65%) of 17 CVL individuals were seropositive (0.46 +/- 0.05). Only three (12%) of 24 HIEA controls reacted in IgG-ELISA. Antileishmanial IgE was detected in 26 (58%) of 45 SC patients (0.35 +/- 0.14), and in all VL patients (0.65 +/- 0.29). These antibodies were also detected in 13(76%) of 17 CVL subjects (0.42 +/- 0.14) while all HIEA controls were seronegative. There was no correlation between antileishmanial IgG and IgE antibody absorbances. Mild periodate oxidation at acid pH of SLA carbohydrates drastically diminished its antigenicity in both IgG and IgE-ELISA, affecting mainly the antigens of 125, 102, 94, and 63 kDa as demonstrated by western immunoblotting.

Identification of immunodominant epitopes of Schistosoma mansoni vaccine candidate antigens using human T cells

Paramyosin and Sm14 are two of the six antigens selected by the World Health Organization as candidates to compose a subunit vaccine against schistosomiasis. Both antigens are recognized by individuals naturally resistant to Schistosoma mansoni infection and induced protective immunity in the murine model. Three Sm14 epitopes and eleven paramyosin epitopes were selected by their ability to bind to different HLA-DR molecules using the TEPITOPE computer program, and these peptides were synthetically produced. The cellular recognition of Sm14 and paramyosin epitopes by peripheral blood mononuclear cells of individuals living in endemic area for schistosomiasis was tested by T cell proliferation assay. Among all Sm14 and paramyosin epitopes studied, Sm14-3 was preferentially recognized by individuals naturally resistant to S. mansoni infection while Para-5 was preferentially recognized by individuals resistant to reinfection. These two peptides represent promising antigens to be used in an experimental vaccine against schistosomiasis, since their preferential recognition by resistant individuals suggest their involvement in the induction of protective immunity.

Immunoglobulin E and systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by intense polyclonal production of autoantibodies and circulating immune complexes. Some reports have associated SLE with a Th2 immune response and allergy. In the present study 21 female patients with SLE were investigated for total IgE and IgE antibodies to dust house aeroallergens by an automated enzyme-linked fluorescent assay, and were also evaluated for antinuclear IgE autoantibodies by a modified indirect immunofluorescence test using HEp-2 cells as antigen substrate. Additionally, immunocapture ELISA was used to investigate serum anti-IgE IgG autoantibodies. Serum IgE above 150 IU/ml, ranging from 152 to 609 IU/ml (median = 394 IU IgE/ml), was observed in 7 of 21 SLE patients (33%), 5 of them presenting proteinuria, urinary cellular casts and augmented production of anti-dsDNA antibodies. While only 2 of 21 SLE patients (9.5%) were positive for IgE antibodies to aeroallergens, all 10 patients with respiratory allergy (100%) from the atopic control group (3 males and 7 females), had these immunoglobulins. SLE patients and healthy controls presented similar anti-IgE IgG autoantibody titers (X = 0.37 +/- 0.20 and 0.34 +/- 0.18, respectively), differing from atopic controls (0.94 +/- 0.26). Antinuclear IgE autoantibodies were detected in 17 of 21 (81%) sera from SLE patients, predominating the fine speckled pattern of fluorescence, that was also observed in IgG-ANA. Concluding, SLE patients can present increased IgE levels and antinuclear IgE autoantibodies without specific clinical signs of allergy or production of antiallergen IgE antibodies, excluding a possible association between SLE and allergy.

HTLV-1 modifies the clinical and immunological response to schistosomiasis

The immunological response in HTLV-1 infected individuals is characterized by a prominent Type-1 cytokine response with high production of IFN-gamma and TNF-alpha. In contrast, helminthic infections and in particular chronic schistosomiasis are associated with a predominant production of IL-4, IL-5, IL-10 and IL-13. Liver fibrosis is the main pathological finding in schistosomiasis that occurs after many years of infection. This pathology is T cell dependent but the immune response mechanisms are not completely understood. The North-east region of Brazil is endemic for both HTLV-1 and schistosomiasis. In the present study the immune response, clinical severity, and therapeutic response to praziquantel of patients with schistosomiasis coinfected with HTLV-1 were compared with patients infected only with S. mansoni. Patients with HTLV-1 and S. mansoni had lower levels of IL-5 (P < 0.05) and higher levels of IFN-gamma (P < 0.05) in cultures stimulated with S. mansoni antigen and decreased S. mansoni antigen specific IgE levels when compared with patients with schistosomiasis without HTLV-1 coinfection. Liver fibrosis was mild in all HTLV-1 coinfected patients and efficacy of praziquantel was lower in patients dually infected than in patients infected only with S. mansoni.

Multiclonal Leishmania braziliensis population structure and its clinical implication in a region of endemicity for American tegumentary leishmaniasis

In Corte de Pedra (CP), northeastern Brazil, Leishmania braziliensis causes three distinct forms of American tegumentary leishmaniasis (ATL). To test the hypothesis that strain polymorphism may be involved in this disease spectrum and accurately characterize the parasite population structure in CP, we compared one L. major, two non-CP L. braziliensis, one CP L. amazonensis, and 45 CP L. braziliensis isolates, obtained over a 10-year period from localized cutaneous, mucosal, and disseminated leishmaniasis patients, with randomly amplified polymorphic DNA (RAPD). Electrophoretic profiles were mostly unique across species. All typing protocols revealed polymorphism among the 45 CP L. braziliensis isolates, which displayed eight different RAPD patterns and greater than 80% overall fingerprint identity, attesting to the adequacy of the tools to assess strain variability in CP's geographically limited population of parasites. The dendrogram based on the sum of RAPD profiles of each isolate unveiled nine discrete typing units clustered into five clades. Global positioning showed extensive overlap of these clades in CP, precluding geographic sequestration as the mechanism of the observed structuralization. Finally, all forms of ATL presented a statistically significant difference in their frequencies among the clades, suggesting that L. braziliensis genotypes may be accompanied by specific disease manifestation after infection.

IgG anti-IgE autoantibodies in visceral leishmaniasis

Procedures for IgG depletion in visceral leishmaniasis (VL) and schistosomiasis sera using Sepharose-protein G beads also deplete IgE. In this study, the presence of IgG anti-IgE autoantibodies in sera from patients with VL (n = 10), and hepatic-intestinal schistosomiasis (n = 10) and from healthy individuals (n = 10) was investigated. A sandwich ELISA using goat IgG anti-human IgE to capture serum IgE and goat anti-human IgG peroxidase conjugate to demonstrate the binding of IgG to the IgE captured was performed. VL sera had higher titers (p < 0.05) of IgG anti-IgE autoantibodies (OD = 2.01 +/- 0.43) than sera from healthy individuals (OD = 1.35 +/- 0.16) or persons infected with Schistosoma mansoni (OD = 1.34 +/- 0.18). The immunoblotting carried out with eluates from Sepharose-protein G beads used to deplete IgG from these sera and goat anti-human IgE peroxidase conjugate, showed a similar pattern of bands, predominating the 75 kDa epsilon-heavy chain and also polypeptides resulting from physiological enzymatic digestion of IgE. A frequent additional band immediately above 75 kDa was observed only in VL sera.

Influence of human T-cell lymphocytotropic virus type 1 infection on serologic and skin tests for strongyloidiasis

The aim of this study was to determine whether human T-cell lymphocytotropic virus type 1 (HTLV-1) infection may affect the levels of parasite-specific immunoglobulin (Ig) G and IgE and the positivity of the skin test for strongyloidiasis. Participants included 67 patients with strongyloidiasis (40 without HTLV-1 infection and 27 coinfected with HTLV-1). We determined IgG and IgE levels by enzyme-linked immunosorbent assay, and the immediate hypersensitivity skin test was performed with the metabolic Strongyloides stercoralis antigen. Specific IgE levels and the size of skin reactions in patients without HTLV-1 were higher (P < 0.01) than those observed in patients coinfected with HTLV-1. Additionally, 89% of patients without HTLV-1 had specific IgE and 92.5% had positive skin tests; however, these values were significantly reduced (P < 0.01) in patients coinfected with HTLV-1 (44% and 59%, respectively). These data show that HTLV-1 infection decreases the sensitivity of detection of S. stercoralis-specific IgE, the size of the immediate hypersensitivity reaction, and the sensitivity of these tests in the diagnosis of strongyloidiasis.

[Evaluation of the sensitization power of Montenegro skin test]

The Montenegro skin test, used to diagnose cutaneous leishmaniasis, is now being considered to detect immunogenicity after vaccination. In this study, we evaluated the ability of this test to induce immune response and IFN-g production in subjects not previously exposed to Leishmania. The Montenegro skin test was performed using antigens of L. amazonensis produced by our laboratory (group I) or by FIOCRU-RJ (group II). At day 30, 33% of the subjects from group I and 42% from group II were positive, compared to 67% from group I and 50% from group II at day 90. IFN-y was detected in 56 % of subjects from group I and 17% from group II at day 30 (169+/-309 and 11+/-36pg/ml) and in 67% from group I and 58% from group II by day 360 (69+/-107 and 18+/-20pg/ml). These data demonstrate that the Montenegro skin test induces not only a delayed hypersensitivity reaction, but also IFN-y production.

HTLV-1 decreases Th2 type of immune response in patients with strongyloidiasis

Eosinophils, immunoglobulin (Ig)E and cytokines have important roles in defence mechanisms against helminths. In this study, the influence of HTLV-1 infection, characterized by a Th1 type of immune response, was evaluated on the cytokine pattern and parasitic specific IgE response in patients with strongyloidiasis. Patients were divided into four groups: strongyloidiasis without HTLV-1 infection, strongyloidiasis with HTLV-1, HTLV-1 without strongyloidiasis and controls without either helminth infection or HTLV-1. The cytokine profile was determined in supernatants of mononuclear cells stimulated with Strongyloides stercoralis crude antigen and the parasite specific IgE was measured by ELISA. Patients coinfected with HTLV-1 had higher levels of interferon (IFN)-gamma and interleukin (IL)-10 (P < 0.05) and lower levels of IL-5 and IgE (P < 0.05) than patients with strongyloidiasis without HTLV-1. There was an inverse relationship between IFN-gamma and IL-5 (P = 0.01; rs = - 0.37) and between IFN-gamma and parasite specific IgE (P = 0.01; rs = - 0.39), and a direct relationship between IFN-gamma and IL-10 (P = 0.04; rs = 0.35). These data show that coinfection with HTLV-1 decreases IL-5 and IgE responses in patients with strongyloidiasis consistent with a relative switch from Th2 to Th1 response. Immunological responses such as these are important in the control of this helminthic infection.

Successful treatment of refractory mucosal leishmaniasis with pentoxifylline plus antimony

Mucosal leishmaniasis is characterized by an intense inflammatory reaction and tissue damage with few parasites in the lesion. On the basis of previous observations that suggest a possible role of tumor necrosis factor alpha (TNF-alpha) in the pathology of this disease, an open-label study was performed to evaluate the efficacy of the treatment with an inhibitor of TNF-alpha (pentoxifylline) associated to antimony therapy in 10 patients with refractory mucosal leishmaniasis. Patients were treated with pentavalent antimony (20 mg per kilogram of body weight per day) plus orally administered pentoxifylline 400 mg 3 times daily for 30 days. Nine of 10 patients fulfilled the criteria for cure: they experienced complete reepithelization of the mucosal tissue 90 days after therapy and displayed no evidence of relapse at 1 year of follow-up. The TNF-alpha levels before therapy (776 +/- 342 pg/mL) fell to 94 +/- 57 pg/mL (P < 0.05) within 60 days after therapy. Our results indicate that pentoxifylline plus antimony therapy should be considered in all patients with mucosal leishmaniasis that is refractory to treatment.

Morbidity associated with Schistosoma mansoni infection determined by ultrasound in an endemic area of Brazil, Caatinga do Moura

Morbidity in schistosomiasis is caused by a granulomatous response to Schistosoma mansoni eggs deposited in peripheral portal veins. Ultrasonography has been useful to assess the impact of control programs on the prevalence of hepatic fibrosis. In the present study, ultrasonographic criteria proposed by the World Health Organization were used to classify the degree of hepatic fibrosis in 164 schistosomiasis patients from an endemic area of Brazil. The majority of subjects (89%) had degree I or II hepatic fibrosis. Periportal tract thickness, portal vein diameter, splenic vein diameter, and spleen size were positively correlated (P < 0.01). Ultrasonography was repeated on 21 patients one year later and hepatic fibrosis had progressed in 17. Ultrasonography was performed after treatment on 39 subjects and periportal fibrosis had regressed in 27.

Cytokine profile and immunomodulation in asymptomatic human T-lymphotropic virus type 1-infected blood donors

The modulation of the immune response has been used as therapy for clinical disorders associated with human T-lymphotropic virus type 1 (HTLV-1) infection. In this study, the cytokine profile was evaluated in 26 asymptomatic HTLV-1 blood donors. Additionally, both the cell responsible for producing interferon-gamma (IFN-gamma) and the role of exogenous interleukin (IL)-10 in downregulating IFN-gamma production were studied. Cytokine levels were determined in supernatants of unstimulated lymphocyte cultures by enzyme-linked immunosorbent assay. The levels of IFN-gamma, tumor necrosis factor-alpha, IL-5, and IL-10 were higher in supernatants of the lymphocyte cultures taken from HTLV-1-infected donors than in those taken from healthy subjects. Although depletion of CD8+ T cells and natural killer cells did not affect IFN-gamma production, depletion of CD4+ T cells significantly decreased IFN-gamma production. Furthermore, at a concentration of 2 ng/ml, IL-10 had only a minimum effect on IFN-gamma production, although at high concentrations (100 ng/ml), IL-10 decreased IFN-gamma production by 50% in HTLV-1-infected individuals. These data indicate that both T helper 1 and T helper 2 cytokines are elevated in HTLV-1 infection and that IL-10 in high concentrations modulates IFN-gamma production in these patients.

Inverse association between skin response to aeroallergens and Schistosoma mansoni infection

BACKGROUND

Helminthic infections and allergic disease are highly prevalent in many areas of the world. It is known that IgE antibodies are involved in the pathogenesis of both helminthiasis and atopy. However, the consequences of the presence of helminthic infections in atopic patients are still not completely understood.

METHODS

Subjects infected by Schistosoma mansoni with more than 200 eggs/g of feces (n = 42) and uninfected subjects (n = 133) were selected from an endemic area of schistosomiasis. The history of allergy and results of the immediate hypersensitivity prick tests with inhalant allergen extracts were registered. Total IgE and IgE specific to S. mansoni and aeroallergens were measured in serum by ELISA.

RESULTS

The proportion of individuals with a positive skin test to allergens was higher in the uninfected group (24.3%) than in the group with more than 200 eggs/g of feces (4.8%). The odds of atopy (defined as a positive test for at least one of the antigens) were 5 times higher (odds ratio = 7.0; 95% confidence interval = 1.6-31.1%; p = 0.01) in the uninfected group, after taking into account the potential influence of gender and age. While there was a tendency for higher total and S. mansoni-specific IgE levels in infected patients, an opposite trend, that is higher aeroallergen-specific IgE, was observed in uninfected subjects.

CONCLUSIONS

There was a strong and statistically significant inverse association between the immediate skin test response to common aeroallergens and infection by S. mansoni. The results indicate that immediate hypersensitivity reactions may be suppressed in S. mansoni-infected individuals.

IL-10 and IL-12 are the main regulatory cytokines in visceral leishmaniasis

Visceral leishmaniasis (VL) is characterized by the absence of cytokines such as IFN-gamma and IL-12. Cure of VL is associated with a restoration of the ability to make these cytokines. The aim of the present study was to evaluate the role of IL-12 in the recovery of the ability to produce IFN-gamma and to test whether or not IL-4 IL-10 and/or TGF-beta could suppress IFN-gamma production by PBMC from treated VL patients. High stimulation index (SI) of proliferation was observed in PBMC from subjects stimulated with Leishmania chagasi antigen (181+/-83). Neutralizing IL-12 inhibited lymphoproliferation [stimulation index (SI) of 210+/-114 to 1+/-0.6 (P<0.01)] and/or the production of IFN-gamma [2792+/-402 pg/ml to 407+/-449 pg/ml (P<0.01)]. Recombinant IL-10 abrogated the lymphoproliferation (SI=2+/-3) while recombinant IL-4 or TGF-beta had no effect on this response (147+/-22 and 194+/-12 respectively). IFN-gamma was high when PBMCs were stimulated with L. chagasi (873+/-400 pg/ml) and this was abrogated by the addition of IL-10 (5+/-2 pg/ml). In contrast neither IL-4 or TGF-beta suppressed IFN-gamma production (837+/-244 pg/ml and 759+/-523 pg/ml). These results indicate that IL-12 plays an important role in the ability of treated VL patients to make IFN-gamma and that IL-10 but not IL-4 or TGF-beta inhibits this response.

Human immune responses to Schistosoma mansoni vaccine candidate antigens

To determine the naturally occurring immunological responses to the Schistosoma mansoni antigens paramyosin, IrV-5, Sm-23 (MAP-3), and triose phosphate isomerase (MAP-4), a total of 119 subjects from an area of endemicity for schistosomiasis, including "resistant" subjects (n = 17) were evaluated. Specific immunoglobulin G1 (IgG1), IgG2, IgG3, IgG4, and IgA levels for each of the antigens and the cytokine profile in culture supernatants from antigen-stimulated peripheral blood mononuclear cells (PBMC) were determined. Although all the subjects had a high degree of contaminated water exposure, their infection levels were variable (0 to 1,128 eggs/g of stool). There were direct correlations between infection levels and levels of SWAP- and paramyosin-specific IgG1 and IgG4 (P < 0.05). However, an inverse correlation between infection levels and specific IgG2 to IrV-5 (P < 0.01) was observed. The evaluation of the cytokine profile (interleukin 5 [IL-5], IL-10, gamma interferon [IFN-gamma], and tumor necrosis factor alpha) in response to these antigens showed inverse correlations between the degree of infection and IFN-gamma levels in PBMC supernatants stimulated with paramyosin (P < 0.05) and IrV-5 (P < 0.01). Additionally, inverse correlations between the degree of infection and IL-5 levels in MAP-3- and MAP-4-stimulated PBMC supernatants (P < 0.01) were found. Logistic regression analysis was performed to adjust the results of cytokine profile by age. IL-5 production in MAP-3-stimulated PBMC supernatants was associated with lower infection levels (odds ratio = 11.2 [95% confidence interval, 2.7 to 45.8]).

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.