A GDPR-compliant information system to improve community primary care in a middle income country

Background

A strong primary health care (PHC) is associated to better overall health system results. Brazil has good results in PHC in the last decades, integrating 260,000 community health workers (CHW) in 43,000 family health teams (FHT), assisting 90 million people and delivering 500 million health activities yearly, such as home visits, consultations, colposcopy, etc. We address the challenges of incorporating CHA-produced data to official electronic health records, automate its analysis and promote information use by FHT to plan activities & prioritize individuals considering social determinants of health, clinical data and treatment plans. Our study developed a general data protection regulation (GDPR) compliant information system to improve community health agents and family health teams coordination of care in order to address this challenge.

Methods

The intervention was developed using UX techniques and combines Apps and Web dashboards, issuing digital alerts to the FHT and municipal health manager, regarding individual health status and pending care for each covered individual. The research used the “Monitoring and Evaluating Digital Health Interventions” toolbox by World Health Organization (WHO), and GDPR compliance was attained by terms of use acceptance, pseudonymisation and anonymization procedures.

Results

Stage 1 and Stage 2 Maturity tests with doctors, nurses and CHA showed good feasibility, usability and user satisfaction of the solution. UX and Qualitative Assessment are reported separately.

Conclusions

Results so far point that the solution is viable and acknowledged as useful by health professionals. Stage 3 (Pilot) will run in September 2020 in two different cities to test efficacy and health system adherence in real world setting. Digital health interventions are powerful tool to improve health care system performance, particularly in Primary Health Care.

Key messages

Digital Health Intervention are viable in Primary Care as long as they reduce health profesisonal burden and increase service quality. Brazil is a promising environment for Digital Health. Careful planning, development and deployment are essential in the process.

Use of digital tools by PHC professionals as instrument for health decision-making

Background

Investments have been made in precision public health strategies, as a way to better assess needs and evaluate the health services. Experiences point out that the computerization of health systems reduces costs and improves the quality of information. Primary Health Care (PHC) workers are key elements of this transformation, which can be enhanced with the use of digital health strategies. This paper aims to know the perception of the use of digital tools provided by the Ministry of Health by PHC workers in municipalities in the state of Ceará/Brazil.

Methods

Focus groups and field monitoring were carried out with different professional profiles. The inclusion criterion was the use of digital tools in their daily work. Questionnaires were built to conduct semi-structured interviews. The analyzes were made using content analysis method.

Results

Among the 21 participants (32-49 years old, mostly female),3 reported not having digital knowledge prior to the use of digital tools in their daily work. Mostly associated the use of digital tools with greater agility and ease in the work routine and greater accuracy of information. The challenges were mainly related to the use of the equipment(tablet),such as fear of breakage, theft and problems in the synchronization of the information system. There was a consensus that the data collected are useful, however they are underutilized for the work process in PHC.

Conclusions

The use of digital tools in the health work process is able to foster the critical view of professionals for analysis and decision making, pointing out strategies to face health issues in the territories. Pointed out as a facilitator in daily work, the use of digital tools does not exclude the use of paper sheets. Despite the greater supply of data, these are not used to their full potential, mainly due to insufficient time, given the numerous tasks for professionals.

Key messages

Carefully planned, developed and deployed digital interventions are powerful tools to improve health care system performance. The use of digital tools in the health work process is able to foster the critical view for analysis and decision making, pointing out strategies to face health issues in the territories.

The Centre for Data and Knowledge Integration for Health (CIDACS): Linking Health and Social Data in Brazil

The Centre for Data and Knowledge Integration for Health (CIDACS) was created in 2016 in Salvador, Bahia-Brazil with the objective of integrating data and knowledge aiming to answer scientific questions related to the health of the Brazilian population. This article details our experiences in the establishment and operations of CIDACS, as well as efforts made to obtain high-quality linked data while adhering to security, ethical use and privacy issues. Every effort has been made to conduct operations while implementing appropriate structures, procedures, processes and controls over the original and integrated databases in order to provide adequate datasets to answer relevant research questions. Looking forward, CIDACS is expected to be an important resource for researchers and policymakers interested in enhancing the evidence base pertaining to different aspects of health, in particular when investigating, from a nation-wide perspective, the role of social determinants of health and the effects of social and environmental policies on different health outcomes.

Challenges in the research and development of new human vaccines

The field of vaccinology was born from the observations by the fathers of vaccination, Edward Jenner and Louis Pasteur, that a permanent, positive change in the way our bodies respond to life-threatening infectious diseases can be obtained by specific challenge with the inactivated infectious agent performed in a controlled manner, avoiding the development of clinical disease upon exposure to the virulent pathogen. Many of the vaccines still in use today were developed on an empirical basis, essentially following the paradigm established by Pasteur, "isolate, inactivate, and inject" the disease-causing microorganism, and are capable of eliciting uniform, long-term immune memory responses that constitute the key to their proven efficacy. However, vaccines for pathogens considered as priority targets of public health concern are still lacking. The literature tends to focus more often on vaccine research problems associated with specific pathogens, but it is increasingly clear that there are common bottlenecks in vaccine research, which need to be solved in order to advance the development of the field as a whole. As part of a group of articles, the objective of the present report is to pinpoint these bottlenecks, exploring the literature for common problems and solutions in vaccine research applied to different situations. Our goal is to stimulate brainstorming among specialists of different fields related to vaccine research and development. Here, we briefly summarize the topics we intend to deal with in this discussion.

Changes in amounts of total salivary gland proteins of Lutzomyia longipallpis (Diptera: Psychodidae) according to age and diet

Saliva plays important roles in facilitation of a bloodmeal, lubrication of mouthparts, and parasite transmission for some vector insects. Salivary composition changes during the lifetime of an insect, and differences in the salivary profile may influence its functions. In this report, the amount and profile of salivary gland protein of the American visceral leishmaniasis vector Lutzomyia longipalpis (Lutz & Neiva, 1912) were analyzed at different times of insect development and diet. Protein content from unfed female sand flies increased significantly with age, and a significant difference was observed in sugar-fed females during the first 10 d of adult life. Salivary protein content sharply decreased 1 d after blood feeding, with gradual increase in concentration the following days. SDS-polyacrylamide gel electrophoresis analysis revealed that most polypeptides present in the saliva of sugar-fed also were present in the saliva of blood-fed females. Understanding changes in sand fly's saliva contents at distinct days after emergence and the influence of a bloodmeal in this aspect may reveal the role played by saliva during leishmaniasis transmission.

Role of Sand Fly Saliva in Human and Experimental Leishmaniasis: Current Insights

Leishmaniases are wide spread diseases transmitted to their vertebrate host by infected sand fly. The saliva from these arthropods contains a vast repertoire of pharmacologically active molecules that hampers the host's haemostatic, inflammatory and immune responses. The early interactions between Leishmania and the host's immune response are closely linked to disease evolution or protection against the protozoan, and the ectoparasite saliva contributes directly to these interactions. Current studies have depicted these features, and these relations are being widely explored. There are concrete indications that the host response against sand fly saliva influences disease outcome in leishmaniasis. Additionally, there are demonstrations that immunization with whole sand fly saliva, or its components, leads to protection against leishmaniasis in different host species. The combination of these evidences opens up optimistic perspectives for improving vaccine development against Leishmania infection.

Leishmanial infection: analysis of its first steps. A review

The first steps in leishmaniasis are critical in determining the evolution of the disease. Major advances have recently been done in understanding this crucial moment. Fundamental research in parasite-vector interaction, parasite biology, insect saliva, and vertebrate host response have shed new light and uncovered a most fascinating and complex moment in leishmaniasis. We review here some of these aspects and we try to connect them in a logical framework.

Egg yolk anti-BfpA antibodies as a tool for recognizing and identifying enteropathogenic Escherichia coli

Enteropathogenic Escherichia coli (EPEC) is a major aetiological agent of childhood diarrhoea in developing countries. The structural repeating protein A subunit, BfpA, found in the bundle-forming pilus, is one of the virulent factors for EPEC pathogenesis. Recombinant BfpA in laying hens elicited sustained and vigorous antibody production. Immunoglobulin Y (IgY) anti-BfpA antibodies were recovered from egg yolk, purified and characterized. Immunoadsorption with whole extracts of the isogenic E. coli EPEC adherence factor (EAF) strain that lacks BfpA rendered the resulting IgY preparations capable of: (a) recognizing purified or recombinant BfpA proteins in a dose-dependent fashion; (b) blocking the colonization of HeLa cells by EPEC EAF+, in vitro; (c) specifically identifying E. coli bearing EAF+; and (d) inhibiting the growth of E. coli EAF+ but not the EAF strain. IgY anti-BfpA is potentially useful as a specific, low-cost immunobiological reagent to screen human faecal specimens for the presence of EPEC.

Leishmania (Leishmania) chagasi infection alters the expression of cell adhesion and costimulatory molecules on human monocyte and macrophage

The initial steps of Leishmania infection in humans are largely unknown. There is limited information on the Leishmania infected human monocytes, the first cells that the parasite lives in, particularly related to costimulatory molecules. We show here that Leishmania (L.) chagasi infection avoids inducing proinflammatory molecules and has striking down modulating effects on human monocytes or macrophages. It does not induce CD54, interleukin (IL)-12 or tumour necrosis factor-alpha, potent proinflammatory cytokines and down modulates CD11b expression in monocytes. Lipopolysaccharide stimulated IL-12 (p40) levels, CD54 and HLA-DR expression are diminished in infected monocytes as well as interferon-gamma stimulated HLA-DR and HLA-ABC expression in infected macrophages. There is a negative correlation between CD54 and CD86 expression in both monocytes and macrophages. The depressed expression of class I and II molecules, absence of key proinflammatory cytokines and impaired expression of costimulatory molecules induced by L. chagasi could leave the immune system, at least in its initial phases in anergy or ignorance.

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.

Differences in gamma interferon production in vitro predict the pace of the in vivo response to Leishmania amazonensis in healthy volunteers

The initial encounter of Leishmania cells and cells from the immune system is fundamentally important in the outcome of infection and determines disease development or resistance. We evaluated the anti-Leishmania amazonensis response of naive volunteers by using an in vitro priming (IVP) system and comparing the responses following in vivo vaccination against the same parasite. In vitro stimulation allowed us to distinguish two groups of individuals, those who produced small amounts of gamma interferon (IFN-gamma) (n = 16) (low producers) and those who produced large amounts of this cytokine (n = 16) (high producers). IFN-gamma production was proportional to tumor necrosis factor alpha and interleukin 10 (IL-10) levels but did not correlate with IL-5 production. Volunteers who produced small amounts of IFN-gamma in vitro remained low producers 40 days after vaccination, whereas high producers exhibited increased IFN-gamma production. However, 6 months after vaccination, all individuals tested produced similarly high levels of IFN-gamma upon stimulation of their peripheral blood mononuclear cells with Leishmania promastigotes, indicating that low in vitro producers respond slowly in vivo to vaccination. In high IFN-gamma producers there was an increased frequency of activated CD8(+) T cells both in vitro and in vivo compared to the frequency in low producers, and such cells were positive for IFN-gamma as determined by intracellular staining. Such findings suggest that IVP responses can be used to predict the pace of postvaccination responses of test volunteers. Although all vaccinated individuals eventually have a potent anti-Leishmania cell-mediated immunity (CMI) response, a delay in mounting the CMI response may influence resistance against leishmaniasis.

Treatment of multiple sclerosis patients with interferon-beta primes monocyte-derived macrophages for apoptotic cell death

Although interferon (IFN)-beta has shown a significant clinical benefit in multiple sclerosis (MS), its mechanism of action remains unclear. We found that IFN-beta treatment of patients with MS resulted in a significant increase in apoptotic cell death (measured by annexin V staining and nuclear fragmentation) of monocyte-derived macrophages, as compared with cells derived from patients before treatment. Stimulation of the cells with IFN-beta in vitro resulted in an even further increase of annexin V binding, as well as increased Fas (CD 95, APO-1) expression. However, no increased Fas expression, apoptotic monocytes, or monocytopenia were observed upon in vivo treatment. This indicates that IFN-beta does not deliver a death signal to monocytes but rather primes for subsequent macrophage apoptosis upon activation or differentiation.

In vivo lymphocyte activation and apoptosis by lectins of the Diocleinae subtribe

This paper reports the overall effects of three lectins, extracted from Canavalia brasiliensis, Dioclea violacea, and D. grandiflora, on BALB/c mice popliteal draining lymph nodes. These lectins have presented high stimulatory capacity on lymph node T cells. Additionally, they were able to induce apoptosis and inflammation (frequently associated with high endothelial venule necrosis). The data presented here suggest that the Diocleinae lectins studied can stimulate in vivo T cell activation and apoptosis, as well as present important side effects.

Revisiting proteus: do minor changes in lectin structure matter in biological activity? Lessons from and potential biotechnological uses of the Diocleinae subtribe lectins

Significant differences in function have been observed among lectins structurally similar to concanavalin A, but their high homology with this widely used lectin has kept them in obscurity. The observation of large differences in the potency of many of these Diocleinae lectins as stimulators of Interferon-g production by human peripheral blood mononuclear cells has lead to a major effort to unravel their chemical structure and biological activity. Modeling studies of some of these lectins reveal conformational changes in side chains of some residues involved in the carbohydrate-binding site, with possible effects on the ability of these proteins to recognize specific carbohydrate structures. Additionally, all them constitute in fact a mixture of isolectins, which in different proportions could lead to diverse effects. The present review of the biological actions of Diocleinae lectins includes several in vitro and in vivo immunological findings, as well as their effects on insect growth and reproduction. In these systems Diocleinae lectins proved to be quite diverse in their potency. Such diversity in the biological activity of highly related proteins recalls the origin of the name protein: like Proteus, the capability of assuming various forms is the essential feature of this class of molecules.

Flow cytometric determination of cellular sources and frequencies of key cytokine-producing lymphocytes directed against recombinant LACK and soluble Leishmania antigen in human cutaneous leishmaniasis

Leishmaniasis, caused by infection with the protozoan parasite Leishmania, affects millions of individuals worldwide, causing serious morbidity and mortality. This study directly determined the frequency of cells producing key immunoregulatory cytokines in response to the recombinant antigen Leishmania homolog of receptors for activated kinase C (LACK) and soluble leishmania antigen (SLA), and it determined relative contributions of these antigens to the overall cytokine profile in individuals infected for the first time with Leishmania braziliensis. All individuals presented with the cutaneous clinical form of leishmaniasis and were analyzed for proliferative responses to LACK antigen and SLA, frequency of lymphocyte subpopulations (analyzed ex vivo), and antigen-induced (LACK and SLA) cytokine production at the single-cell level (determined by flow cytometry). The following were determined. (i) The Th1-type response previously seen in patients with cutaneous leishmaniasis is due to gamma interferon (IFN-gamma) production by several different sources, listed in order of contribution: CD4(+) T lymphocytes, CD4(-), CD8(-) lymphocytes, and CD8(+) T lymphocytes. (ii) SLA induced a higher frequency of lymphocytes producing IFN-gamma and tumor necrosis factor alpha (TNF-alpha) than did LACK. (iii) LACK induced an activation of monocyte populations as reflected by an increased percentage of CD14-positive cells. (iv) Neither SLA nor LACK induced detectable frequencies of cells producing interleukin-4 (IL-4) or IL-5. These data demonstrated a multifaceted immune response to SLA in human leishmaniasis involving Th1 CD4(+) T lymphocytes (IFN-gamma(+) and IL-10(-)/IL-4(-)), Tc1 CD8(+) T cells (IFN-gamma(+), and IL-10(-)/IL-4(-)), and a high frequency of TNF-alpha-producing lymphocytes. Moreover, it was determined that the recombinant antigen LACK acts as a weak inducer of Th1-type lymphocyte responses compared to SLA.

IFN-beta and TGF-beta differentially regulate IL-12 activity in human peripheral blood mononuclear cells

Both IFN-beta and TGF-beta have demonstrated their ability to antagonize several of the stimulatory activities of IFN-gamma on human macrophages, thereby classifying them as Th2-like. Aiming at a further characterization of their role in Th1/Th2 development, we studied their possible interaction with IL-12, the key Th1 cytokine. We found that IFN-beta by itself induced modest amounts of IFN-gamma, but was able to synergize with IL-12 for IFN-gamma induction. TGF-beta, on the other hand, had no effect by itself and inhibited significantly the IL-12-induced IFN-gamma secretion. The differential effect of IFN-beta and TGF-b on IL-12 bioactivity was most pronounced upon IFN-gamma synthesis, since IFN-beta induced only marginal amounts of IL-10 and IL-12 and TGF-beta diminished constitutive IL-10 production, while neither had a significant effect on TNF-alpha production. Although monocytes did not produce detectable IFN-gamma with any of the stimuli, adherent cells were found to cooperate with non-adherent lymphocytes for maximal IFN-gamma production. However, IL-18, a monocyte-derived IFN-gamma-inducing cytokine able to synergize with IL-12, was undetectable in IFN-beta or IFN-beta+IL-12-stimulated cells. In conclusion, the ability of IFN-beta to synergize with IL-12 for IFN-gamma synthesis, without significant concomitant IL-10 production, suggest a strong boost to Th1 development, which seems to be IL-18-independent.

Characterizing subpopulations of neoplastic cells in serous effusions. The role of immunocytochemistry

OBJECTIVE

To analyze the role of immunochemistry in serous effusions.

STUDY DESIGN

We analyzed cell blocks of 18 pleural and 18 peritoneal effusions diagnosed as malignant (18), benign (14) and suspicious (4). They were immunostained by the avidin-biotin complex method with a panel of four monoclonal antibodies--CEA, Ber-EP4, LeuM1 (CD15) and p53--and, for lectins (Ulex europaeus) UEA-l, ConA and ConBr.

RESULTS

Seventeen of the 18 cases of adenocarcinoma were positive for CEA (95%), 12 (66.6%) for Ber-EP4, 11 (61%) for CD15 and 11 (61%) for p53. Twelve of the 18 (66.6%) were positive for UEA-1, CEA, Ber-EP4 and CD15. UEA-1 did not react with mesothelial cells. p53 Gave a positive reaction in only one case, reactive mesothelial cells. ConA and ConBr reacted indiscriminately with benign and malignant cells; thus, it was not useful in distinguishing between these cells.

CONCLUSION

In this context no antibody used alone is reliable for corroborating a diagnosis, but the selective use of a small panel of three markers (CEA, Ber-EP4 and LeuM1) can be very useful in solving diagnostic difficulties in the cytodiagnosis of serous effusions.

Human immune response to sand fly salivary gland antigens: a useful epidemiological marker?

Antibody (IgG) responses to salivary gland homogenate and to a recombinant salivary protein from the sand fly Lutzomyia longipalpis were investigated using sera from children living in an endemic area of visceral leishmaniasis in Brazil. We classified children into four groups according to their responses to Leishmania antigen: (Group I) positive serology and positive delayed type hypersensitivity (DTH), (Group II) positive serology and negative DTH, (Group III) negative serology and positive DTH, and (Group IV) negative serology and negative DTH. A highly significant correlation was found between anti-salivary gland IgG levels and DTH responses. An L. longipalpis salivary recombinant protein used as an antigen in an enzyme-linked immuno sorbent assay (ELISA) gave a significant but different result. A positive correlation was found between anti-Leishmania IgG and anti-recombinant protein IgG titers. The results indicate that sand fly salivary proteins may be of relevance to the study the epidemiology of leishmaniasis.

A dhfr-ts- Leishmania major knockout mutant cross-protects against Leishmania amazonensis

E10-5A3 is a dhfr-ts- Leishmania major double knockout auxotrophic shown previously to induce substantial protection against virulent L. major infection in both genetically susceptible and resistant mice. We investigated the capacity of dhfr-ts- to protect against heterologous infection by L. amazonensis. The degree of protection was evaluated by immunization of BALB/c or C57BL/6 mice with E10-5A3, followed by L. amazonensis challenge. Whether immunized by subcutaneous (SC) or intravenous (IV) inoculation, susceptible and resistant mice displayed a partial degree of protection against challenge with virulent L. amazonensis. SC-immunized BALB/c mice developed lesions 40 to 65% smaller than non immunized mice, while IV immunization led to protection ranging from 40 to 75% in four out of six experiments compared to non immunized animals. The resistant C57BL/6 mice displayed comparable degrees of protection, 57% by SC and 49% by IV immunization. Results are encouraging as it has been previously difficult to obtain protection by SC vaccination against Leishmania, the preferred route for human immunization.

Lectin-induced nitric oxide production

Considering that nitric oxide (NO) may be involved in anti-tumoral and anti-parasite lectin effects, in this report we investigated whether lectin induces NO production. Lectins from Canavalia brasiliensis, Dioclea grandiflora, Pisum arvense (PAA), and concanavalin A induced murine peritoneal cells to produce NO in vitro. PAA induced similar levels to that obtained with lipopolysaccharide plus interferon-gamma. NO production by adherent cells was significantly lower than that of unfractionated cells, suggesting a combination of lectin stimuli directly on macrophages and via lymphocyte stimulation. Ex vivo experiments showed that cells stimulated in vivo could maintain NO production in vitro without further stimuli. NO synthesis blockage in vivo can significantly increase cell numbers in draining lymph nodes after lectin injection compared to unblocked controls, suggesting an in vivo association of lectin stimuli and NO production. Taken together these data show that lectins can induce NO production both in vitro and in vivo.

Immunochemotherapy with interferon-gamma and multidrug therapy for multibacillary leprosy

Treatment for multibacillary leprosy is presently performed with a multidrug therapy (MDT) scheme maintained for 2 years. Leprosy treatment however can benefit from the reduction of length. The lack of interferon-gamma (IFN-gamma) production by lepromatous leprosy (LL) patients' lymphocytes lead us to use this cytokine in the treatment of multibacillary leprosy associated with MDT in the treatment of multibacillary leprosy, and monitor several clinical and immunological parameters during the course of treatment. A total of 20 multibacillary leprosy patients were evaluated, 10 treated with MDT alone, and 10 treated with MDT + 10 daily doses of 2 x 10(6) international units (IU) of recombinant human IFN-gamma/m2 followed by 10 daily doses of 10(7) IU IFN-gamma/m2, intramuscularly, during the first 20 days of MDT. IFN-gamma was well tolerated and did not cause any increase in the rate of leprosy reactions development during treatment. Decrease of bacillary load, fall of anti-Mycobacterium leprae IgG serum antibodies, changes of histological pattern, as well as changes in lymphocyte proliferation assay in response to mitogens (PHA or PWM), M. leprae antigen or PPD was similar in both groups of patients. Among several soluble immunological markers measured before and 30 days after beginning of treatment, levels of soluble IL-2R receptor increased in patients treated with MDT plus IFN-gamma whereas decreased in patients treated with MDT alone. Soluble ICAM-1 levels decreased in the MDT group but did not change in the MDT + IFN-gamma treated patients. Soluble CD4 and soluble CD8 markers did not change significantly in either group of patients. Neopterin, a marker of macrophage activation, increased in all but one patient treated with MDT + IFN-gamma but in none treated with MDT alone, indicating that IFN-gamma was active in vivo. Our findings indicate that despite being able to promote macrophage activation in multibacillary leprosy patients a short course of systemically administered IFN-gamma is not able to change the clinical course of a long standing disease such as leprosy.

Expression of a pilin subunit BfpA of the bundle-forming pilus of enteropathogenic Escherichia coli in an aroA live salmonella vaccine strain

Enteropathogenic Escherichia coli (EPEC) is a major cause of childhood diarrhea in developing countries and is a leading cause of severe diarrheal illness among Brazilian infants. As one approach to constructing a vaccine candidate against diarrhea caused by EPEC, we evaluated whether the pilin subunit (BfpA) of the bundle-forming pilus (BFP) could be expressed by a live Salmonella vaccine strain. Several copies of the coding region of BfpA (bfpA) were amplified by PCR from a preparation of the EAF plasmid of EPEC strain B171 and cloned into plasmid vectors. An intact copy of bfpA was subcloned into the heat inducible prokaryotic expression vector pCYTEXP1, and the resulting pBfpA was used to transform the aroA S. typhimurium strain SL3261, generating SL3261(pBfpA). The recombinant vaccine strain was able to express, but not to process, rBfpA as evidenced by a prominent 21 kDa protein that crossreacted with anti-BFP antiserum found only in extracts of heat-treated SL3261(pBfpA), but not in strains of untreated SL3261(pBfpA) or SL3261 not carrying the plasmid. Furthermore, rBfpA accumulation was not toxic to the Salmonella host, as evidenced by similar plating efficiencies between induced and uninduced strains of SL3261(pBfpA). Finally, SL3261(pBfpA) orally administered to BALB/c mice was capable of eliciting a sustained and vigorous humoral immune response to BfpA, achievable even with a single oral dose of approximately 10(9) organisms. Therefore, this pilin product may serve as a potential immunogen as part of a live combined vaccine strategy to prevent two of the major public health problems in Brazil--salmonellosis and EPEC childhood diahrrea.

Cell-mediated immune responses and cytotoxicity to mycobacterial antigens in patients with tuberculous pleurisy in Brazil

Evaluating human immune response to defined Mycobacterium tuberculosis antigens in patients with different clinical forms of tuberculosis may help in elucidating pathogenesis and in vaccine development. In the present report we evaluated the lymphocyte proliferation, cytokine production and natural killer cell cytotoxicity as parameters to screen four mycobacterial recombinant antigens. Pleural fluid mononuclear cells (PFMC) and peripheral blood mononuclear cells (PBMC) from 13 HIV-negative patients with tuberculous pleurisy, living in a tropical region of Brazil were used in these assays. Crude M. tuberculosis antigen and recombinant 70-, 65- and 38-kDa mycobacterial antigens, induced greater proliferation in PFMC than in PBMC. IFN-gamma, TNF-alpha, IL-4 and IL-10 were evaluated in the PFMC supernatants stimulated by these antigens. Both crude and 70-kDa antigens induced higher levels of IFN-gamma, TNF-alpha and IL-10. There was a significant positive correlation between IFN-gamma and the proliferative response induced by crude M. tuberculosis antigen, and an inverse correlation was identified between IL-10 and cell proliferation. IL-4 was not detected in the supernatants of pleural fluid mononuclear cell cultures stimulated by either crude, or recombinant antigens. TNF-alpha was detected in variable amounts in supernatants of PFMC stimulated by all antigens tested. Natural killer cytotoxicity was induced by both crude and 70-kDa antigen. Our results demonstrate that cells present at the site of disease recognized three of the antigens screened, as shown by lymphocyte proliferation and production of regulatory and inflammatory cytokines, and the results obtained with PFMC were consistently higher than those obtained with homologous PBMC.

Production of host-protective (IFN-gamma), host-impairing (IL-10, IL-13) and inflammatory (TNF-alpha) cytokines by PBMC from leprosy patients stimulated with mycobacterial antigens

The production of IFNgamma, IL-10, IL-13 and TNFalpha was determined using PBMC from 7 tuberculoid (TT) and 7 lepromatous leprosy (LL) patients, after stimulation with several mycobacterial antigens, in an attempt to characterize the cytokine responses to these antigens. The results showed that TT patients displayed higher IFNgamma levels than LL patients with the mycobacterial antigens tested, but no differences in IL-10 production were observed between the two groups. MLSC antigen was associated with the lowest IFNgamma production in TT and LL groups. Only BCG could be identified with stimulation of IFNgamma production in some LL patients. The mycobacterial antigens SP+, SP- and BCG were associated with higher TNFalpha production in patients and controls, suggesting that these antigens could be involved in immunopathological effects. Our findings showed that the antigens tested were associated with a heterogeneous cytokine production in leprosy patients. Further studies are required to establish if an individual antigen can be identified as inducing a protective immune response in leprosy.

Human_leishmaniasis/cytokines.bahia.br

The cell-mediated immune response is critical in the resistance to and recovery from leishmaniasis. Cytokines are central elements in mounting an immune response and have received a great deal of attention in both human and experimental leishmaniasis. IFN-gamma is responsible for macrophage activation leading to leishmanicidal mechanisms. Understanding the balance of cytokines that lead to enhanced production of or synergize with IFN-gamma, and those cytokines that counterbalance its effects is fundamental for developing rational immunotherapeutic or immunoprophylactic approaches to leishmaniasis. Here we focus on the cytokine balance in human leishmaniasis, particularly IL-10 as an IFN-gamma opposing cytokine, and IL-12 as an IFN-gamma inducer. The effects of these cytokines were evaluated in terms of several parameters of the human immune response. IL-10 reduced lymphocyte proliferation, IFN-gamma production and cytotoxic activity of responsive human peripheral blood mononuclear cells. Neutralization of IL-10 led to partial restoration of lymphoproliferation, IFN-gamma production and cytotoxic activity in unresponsive visceral leishmaniasis patients. IL-12 also restored the responses of peripheral blood mononuclear cells from visceral leishmaniasis patients. The responses obtained with IL-12 are higher than those obtained with anti-IL-10, even when anti-IL-10 is combined with anti-IL-4.

Parasite-driven in vitro human lymphocyte cytotoxicity against autologous infected macrophages from mucosal leishmaniasis

Parasite-specific cytotoxicity in human leishmaniasis was evaluated in an autologous system. PBL from cutaneous leishmaniasis (CL) or mucosal leishmaniasis (ML) patients were exposed to Leishmania amazonensis-infected autologous macrophages for 7 days and then used as effector cells in a cytotoxic assay using 51Cr-labeled autologous infected macrophages as targets. Results are reported as LU per 10(7) PBMC. Cytotoxic activity is present in ML (9.7 +/- 2.1 LU/10(7) PBMC) but not in CL (1.5 +/- 2.4 LU/10(7) PBMC) patients' lymphocytes, and the differences were highly significant (p < 0.0001). Both CD8+ T cells and NK cells exhibited cytotoxic activity. Addition of rIL-12, but not of IFN-gamma, during the generation of effector cells increased cytotoxic responses against infected macrophages. On the other hand, addition of mAb against human IL-12 or IFN-gamma during the stimulation of PBL significantly decreased the cytotoxic responses. Addition of IL-10 led to diminished cytotoxic responses, whereas the addition of anti-IL-10 did not significantly increase the cytotoxic responses. The observation of parasite-driven autologous cytotoxic responses in patients with ML, the destructive form of leishmaniasis, but not in CL, suggests that this phenomenon is involved in tissue pathology rather than in protection. Understanding the regulation of cytotoxic responses in leishmaniasis may be relevant to strategies aimed at limiting pathologic tissue destruction.

Parasite-driven in vitro human lymphocyte cytotoxicity against autologous infected macrophages from mucosal leishmaniasis

Parasite-specific cytotoxicity in human leishmaniasis was evaluated in an autologous system. PBL from cutaneous leishmaniasis (CL) or mucosal leishmaniasis (ML) patients were exposed to Leishmania amazonensis-infected autologous macrophages for 7 days and then used as effector cells in a cytotoxic assay using 51Cr-labeled autologous infected macrophages as targets. Results are reported as LU per 10(7) PBMC. Cytotoxic activity is present in ML (9.7 +/- 2.1 LU/10(7) PBMC) but not in CL (1.5 +/- 2.4 LU/10(7) PBMC) patients' lymphocytes, and the differences were highly significant (p < 0.0001). Both CD8+ T cells and NK cells exhibited cytotoxic activity. Addition of rIL-12, but not of IFN-gamma, during the generation of effector cells increased cytotoxic responses against infected macrophages. On the other hand, addition of mAb against human IL-12 or IFN-gamma during the stimulation of PBL significantly decreased the cytotoxic responses. Addition of IL-10 led to diminished cytotoxic responses, whereas the addition of anti-IL-10 did not significantly increase the cytotoxic responses. The observation of parasite-driven autologous cytotoxic responses in patients with ML, the destructive form of leishmaniasis, but not in CL, suggests that this phenomenon is involved in tissue pathology rather than in protection. Understanding the regulation of cytotoxic responses in leishmaniasis may be relevant to strategies aimed at limiting pathologic tissue destruction.

Molecular cloning and characterization of ConBr, the lectin of Canavalia brasiliensis seeds

ConBr, a lectin isolated from Canavalia brasiliensis seeds, shares with other legume plant lectins from the genus Canavalia (Diocleinae subtribe) primary carbohydrate recognition specificity for D-mannose and D-glucose. However, ConBr exerts different biological effects than concanavalin A, the lectin of Canavalia ensiformis seeds, regarding induction of rat paw edema, peritoneal macrophage spreading in mouse, and in vitro human lymphocyte stimulation. The primary structure of ConBr was established by cDNA cloning, amino acid sequencing, and mass spectrometry. The 237-amino-acid sequence of ConBr displays Ser/Thr heterogeneity at position 96, indicating the existence of two isoforms. The mature Canavalia brasiliensis lectin monomer consists of a mixture of predominantly full-length polypeptide (alpha-chain) and a small proportion of fragments 1-118 (beta-chain) and 119-237 (gamma-chain). Although ConBr isolectins and concanavalin A differ only in residues at positions 58, 70, and 96, ConBr monomers associate into dimers and tetramers in a different pH-dependent manner than those of concanavalin A. The occurrence of glycine at position 58 does not allow formation of the hydrogen bond that in the concanavalin A tetramer exists between Asp58 of subunit A and Ser62 of subunit C. The consequence is that the alpha carbons of the corresponding residues in ConBr are 1.5 A closer that in concanavalin A, and ConBr adopts a more open quaternary structure than concanavalin A. Our data support the hypothesis that substitution of amino acids located at the subunit interface of structurally related lectins of the same protein family can lead to different quaternary conformations that may account for their different biological activities.

Variation of cytokine patterns related to therapeutic response in diffuse cutaneous leishmaniasis

Diffuse cutaneous leishmaniasis is a rare entity characterized by disseminated cutaneous nodules associated with specific anergy to leishmanial antigens. A low but not absent IFN-gamma expression by cells present in cutaneous lesions has been documented during the active phase of diffuse cutaneous leishmaniasis. In this study we confirm this observation, and extend it by showing a similar pattern in peripheral blood mononuclear cells and the variation of mRNA cytokine expression pattern during different stages of the disease. During active disease, patients did not express mRNA for IFN-gamma, while expressing mRNA for IL-2, IL-4, and IL-10. In contrast, an expression of IFN-gamma and low IL-10 was observed after treatment-induced transient healing of cutaneous lesions. In three patients we have been able to analyze a third PBMC sample obtained after clinical relapse, documenting in all of them decreased IFN-gamma expression with no expression of IL-10. Although there was an association between the appearance of IFN-gamma expression and clinical improvement, with marked expression of IFN-gamma mRNA and decreased expression of mRNA for IL-10 after treatment, this was not sufficient to prevent relapse in these patients. Therefore, it is possible that factors other than the cytokines characteristic of the Th1 and Th2 balance are implicated in the inability of diffuse cutaneous leishmaniasis patients to mount an anti-Leishmania immune response causing clinical improvement.

Cytotoxicity in patients with different clinical forms of Chagas' disease

There are few studies on cell-mediated cytotoxicity in human Chagas' disease. In the present study, we evaluated peripheral blood mononuclear cell (PBMC) cytotoxicity activity from chagasic patients with different clinical forms of disease. To verify the cytotoxic response, we performed cell lysis assays using 51Cr-labelled K562 cells as targets. Results are reported as lytic units (LU = number of cells required for 30% lysis) per million PBMC. Exposure of patients' PBMC to Trypanosoma cruzi antigen led to an increase in cytotoxic activity compared with unstimulated patient cells against K562. Asymptomatic cardiomyopathy patients had higher responses (37.8 +/- 5.0 LU/10(6) PBMC; mean +/- s.d.) than indeterminate (11.5 +/- 3.6 LU/10(6) and symptomatic cardiomyopathy (7.8 +/- 2.5 LU/10(6)). Normal control PBMC stimulated with T. cruzi antigen had 4.36 +/- 1.31 LU/10(6)) PBMC against K562. Addition of recombinant interferon-gamma (IFN-gamma) did not lead to significant increase in cytotoxicity in any group of patients. On the other hand, recombinant human IL-12 significantly increased cytotoxic responses from symptomatic cardiomyopathy patients and normal controls who presented low levels of cytotoxicity induced by T. cruzi antigen. The combined use of IL-12 and a neutralizing anti-IFN-gamma antibody did not change IL-12-induced cytotoxic responses, showing the direct role of this cytokine on natural killer (NK) cells. NK cells were the main cells responsible for the lysis of K562 target cells as evidenced by testing cell subsets following magnetic cell sorting. These data demonstrate that chagasic patients with different clinical forms of disease have PBMC which respond to T. cruzi antigen with a cytotoxic response, and this response is up-regulated by IL-12.

Interleukin-12 restores interferon-gamma production and cytotoxic responses in visceral leishmaniasis

American visceral leishmaniasis (AVL) is associated with the absence of lymphocyte proliferative responses and interleukin (IL)-2 and interferon-gamma (IFN-gamma) production upon stimulation with Leishmania antigen. In contrast, cure of AVL is associated with restoration of these T cell functions. In the present study, the ability of IL-12, a cytokine that acts on NK and T cells to restore cellular immune responses in AVL, was evaluated. Participants of the study included 12 patients with AVL and 7 subjects cured of AVL. The [3H]thymidine uptake and IFN-gamma production in cultures of peripheral blood mononuclear cells (from AVL patients) stimulated with Leishmania chagasi antigen were 882 +/- 1393 cpm and zero, respectively. Addition of IL-12 enhanced the proliferative response to 5097 +/- 6429 cpm (P < .001) and IFN-gamma production to 305 +/- 325 pg/mL (P < .01). IL-12 also restored cytotoxic activity against the K562 cell line. These results indicate that IL-12 has an important role in the regulation of the cellular immune response in human leishmaniasis.

Biological behavior of Leishmania amazonensis isolated from humans with cutaneous, mucosal, or visceral leishmaniasis in BALB/C mice

Leishmania amazonensis causes a wide spectrum of disease in humans. In this study, we evaluated BALB/c mice infected with five strains of L. amazonensis isolated from patients with either cutaneous, mucosal, or visceral leishmaniasis. Mice infected with cutaneous and mucosal isolates developed ulcerating footpad lesions with parasite-loaded macrophages and extensive tissue destruction. Skin metastases, early dissemination of parasites to the spleen, and high anti-Leishmania antibody levels were also noted. Mice infected with L. amazonensis strains isolated from patients with visceral disease had a controlled infection, with small footpad lesions with mononuclear cell infiltration, few infected macrophages, and granuloma formation. They had no skin metastases, delayed dissemination of the parasite to the spleen, lower levels of IgG and higher levels of IgG2a against L. amazonensis. These findings demonstrate an unexpected resistance of BALB/c mice to the infection with L. amazonensis isolated from patients with visceral leishmaniasis. This resistance seems to be due to differences in these parasites that may be related to the altered course of the disease in humans and in isogenic BALB/c mice.

In vivo protective effect of the lectin from Canavalia brasiliensis on BALB/c mice infected by Leishmania amazonensis

In vivo administration of Canavalia brasiliensis lectin (at the time of infection, or maintained throughout the infection) reduced the lesions of highly susceptible BALB/c mice infected by Leishmania amazonensis. At the doses used C. brasiliensis lectin (ConBr) does not interfere with penetration or fate of Leishmania in the macrophages in vitro. Since Interferon-gamma (IFN-gamma) is the major macrophage activating factor, and considered a critical element in the successful immune response against leishmaniasis, we explored its participation in this phenomenon. ConBr either in vivo or in vitro induced IFN-gamma production in normal or in leishmania-infected BALB/c mice. However we were unable to change the course of disease by in vivo IFN-gamma administration (although IFN-gamma preparations were effective in inducing a leishmanicidal effect in vitro on L. amazonensis-infected peritoneal macrophages). Additionally, IFN-gamma neutralization with anti-IFN-gamma monoclonal antibody did not alter the protection conferred by ConBr administration. These data show that lectin administration in vivo is protective in the otherwise unchecked L. amazonensis infection of BALB/c mice, and suggest that such effect is not mediated by IFN-gamma.

Serum soluble markers in the evaluation of treatment in human visceral leishmaniasis

Visceral leishmaniasis (VL) has a fatal course if not properly treated. Recovery from VL is linked to cellular immune response. Unresponsiveness to antimonial therapy reinforces the importance of determining parameters for treatment assessment. We analysed the pre- and post-treatment serum levels of soluble CD4 (sCD4), sCD8, sIL-2R, soluble intercellular adhesion molecule-1 (sICAM-1) and neopterin in groups of VL patients either responsive or not to standard antimonial therapy. Pretreatment serum levels of all markers except for sICAM-1 were significantly higher in VL patients than in healthy subjects from the same area (P < 0.05). sICAM-1 levels were similar in healthy controls and in VL patients refractory to antimonial therapy (P = 0.25), but significantly higher in patients responsive to treatment (P = 0.02). The comparison of pre- and post-treatment concentrations showed that all markers, except sCD4 and sICAM-1, presented a significant fall (P < 0.05) in patients responsive to antimonial therapy. However, only neopterin presented with levels compatible with those of healthy subjects at the end of treatment (P = 0.30). In refractory patients sICAM-1 presented with post-treatment levels significantly higher than the pretreatment determinations (P = 0.03), while sCD4 experienced a significant drop (P = 0.01). All markers displayed clearly distinct behaviour according to the patient's response to therapy. This makes all soluble molecules studied suitable for use as indicators of antimonial therapy response. Additionally the comparison of pretreatment levels of the markers between responders and refractory patients to antimonial therapy showed that serum concentrations of sIL-2R and sICAM-1 significantly differed among these two groups (P = 0.02 in each case), suggesting that they may be used in future as predictors of antimonial therapy response.

Transforming growth factor-beta in human cutaneous leishmaniasis

Transforming growth factor (TGF)-beta has several downregulatory functions on the immune system: inhibition of interleukin-2 receptor induction, decrease of interferon-gamma-induced class II antigen expression, inhibition of macrophage activation, as well as cytotoxic and lymphokine-activated killer cell generation. TGF-beta has also been recognized as an important immunoregulator in murine leishmaniasis, for which it increases susceptibility to disease. In the present study we evaluate the involvement of TGF-beta in human leishmaniasis in vitro and in patients with cutaneous leishmaniasis. Human macrophages produce active TGF-beta after infection by Leishmania amazonensis (480 +/- 44.7 pg/ml; mean +/- SEM), L. donovani chagasi (295 +/- 7.6 pg/ml), or L. braziliensis (196 +/- 15.7 pg/ml). When TGF-beta was added to cultures of human macrophages infected with L. braziliensis it led to an increase of approximately 50% in parasite numbers as compared with untreated cultures. Exogenous TGF-beta added to macrophage cultures was able to reverse the effect of interferon-gamma in controlling Leishmania growth. Even at 100 IU/ml interferon-gamma the presence of TGF-beta increases the number of intracellular parasites. On the other hand, TNF-alpha at high concentration (100 IU/ml) totally blunts the suppressive effect of TGF-beta. Immunostaining for TGF-beta was observed in the dermis, produced by fibroblasts and occasionally by inflammatory cells in the biopsies from human leishmaniasis lesions, being present in most of the biopsies taken from patients with early cutaneous leishmaniasis (less than 2 months of ulcer development) and in cases of active mucosal leishmaniasis. Taken together these observations suggest an important role for TGF-beta in human leishmaniasis, with its production by infected macrophages being probably related to parasite establishment in the early stages of the disease.

Lymphadenopathy as the first sign of human cutaneous infection by Leishmania braziliensis

This paper describes the presence of transitory lymphadenopathy as an initial sign of cutaneous leishmaniasis, and sometimes the only manifestation of Leishmania braziliensis infection. Ten patients with lymphadenopathy living in an area of L. braziliensis transmission had Leishmania cultivated from their lymph nodes previous to any other manifestation of cutaneous leishmaniasis. Seven of the 10 developed leishmanial ulcers later in the course of infection, whereas lymphadenopathy regressed in three cases and no other sign of infection developed. Results of tests for anti-Leishmania antibodies and an intradermal skin test were positive in four and five patients, respectively, at the time of the diagnosis. The documentation of Leishmania amastigotes in the lymph nodes before any clinical evidence of cutaneous disease indicates that early spread of L. braziliensis from the skin to lymph nodes occurs before a local lesion develops. All medical doctors examining patients coming from endemic areas of leishmaniasis should be aware that lymph node enlargement, even in the absence of a typical ulceration, may be indicative of leishmanial infection and warrants further investigation.

Polar and subpolar diffuse cutaneous leishmaniasis in Brazil: clinical and immunopathologic aspects

BACKGROUND

Diffuse cutaneous leishmaniasis (DCL) is a rare manifestation of human leishmaniasis, characterized by multiple, slowly progressive nodules or plaques without ulceration, involving almost the entire body. It has been suggested, that DCL results from a lack of cell-mediated immunity to leishmanial antigen, leading to uncontrolled parasite growth.

METHODS

We have performed detailed clinical, histopathologic, and immunologic investigations in six patients with DCL. Biopsies were taken from the nodules, processed, and examined for determination of the macrophagic pattern present, based on the intensity of vacuolation and the frequency of vacuolated cells, the parasite index, and the presence of eosinophils. Immunologically, patients were evaluated by their response to intradermal skin test to PPD or leishmania antigen, determination of antileishmania antibodies by immunofluorescent assay, and lymphocyte proliferation assay.

RESULTS

There seemed to be a negative relation between nodules and skin ulcerations, whereas the highest number of parasites were observed in patients with the greatest number of vacuolated macrophages. The delayed hypersensitivity skin test to leishmanial antigen was negative, and antileishmania IgG antibodies were positive in all patients.

CONCLUSIONS

Although all cases fulfill the criteria for being classified as DCL, they present a wide spectrum. Three cases were clearly at the unresponsive pole, and three other cases belonged to the subpolar form of DCL, exhibiting varying weak signs of antiparasite responsiveness.

Up-regulation of T helper 2 and down-regulation of T helper 1 cytokines during murine retrovirus-induced immunodeficiency syndrome enhances susceptibility of a resistant mouse strain to Leishmania amazonensis

Resistance to and recovery from leishmania infection is dependent on cell-mediated immunity. C57BL/6 mice are resistant to Leishmania amazonensis (La) infection but susceptible to LP-BM5 murine leukemia virus (MuLV) infection. MuLV infection leads to a state of immunodeficiency characterized by severe compromise of cell-mediated immunity. When infected with La alone, C57BL/6 mice developed a small transient lesion that evolved to spontaneous healing or a lesion with extremely slow growth. Lesions were predominantly comprised of a lympho-macrophagic infiltrate with few parasitized macrophages. When infected with La and, 4 weeks later, with MuLV (La-MuLV), the mice developed a large uncontrolled nonhealing lesion containing vacuolated and heavily parasitized macrophages. In contrast, mice infected with MuLV first and La 4 weeks later (MuLV-La) developed a small but persistent lesion, characterized histologically by a small number of heavily parasitized macrophages and few lymphocytes. Eight weeks after MuLV infection, both had similar immunological profiles with decreased lymphocyte proliferation, diminished production of interferon-gamma, and high production of interleukins 4 and 10. At the time of L. amazonensis infection, La-MuLV animals have a normal T cell function whereas in MuLV-La mice this function is already impaired; this may influence the recruitment of macrophages to the site of leishmania injection.

Cytotoxicity in human mucosal and cutaneous leishmaniasis

CD8+ T cells and lysis of parasitized macrophages seem to be important in the resistance to murine leishmaniasis. In the present study, we evaluated peripheral blood mononuclear cell (PBMC) from patients with either cutaneous (CL) or mucosal (ML) leishmaniasis in cell lysis assays using 51-Cr-labeled Daudi or K562 cells, or autologous antigen-pulsed macrophages as targets. Results are reported as lytic units (number of cells required for 30% lysis) per million PBMC. Exposure of patient PBMC (n = 12) to lysate from Leishmania amazonensis promastigotes led to an increase in cytotoxic activity compared to unstimulated patient cells against Daudi (81.8 +/- 14.9 vs 13.6 +/- 5 lytic units (LU) per million PBMC; mean +/- SEM) and K562 (65.7 +/- 8.4 vs 13.1 +/- 5 LU/10(6) PBMC). ML had higher responses than CL in both targets (80.4 +/- 11.0 vs 46.4 +/- 11.6 LU/10(6) PBMC for K562, and 104.3 +/- 23.8 vs 59.3 +/- 14.3 LU/10(6) PBMC for Daudi). Normal control PBMC, stimulated with L. amazonensis antigen had 6.32 +/- 3.72 LU/10(6) PBMC against Daudi cells and 9.06 +/- 2.78 LU/10(6) PBMC against K562. The cell responsible for lysis of the K562 cells was characterized as NK, by means of cell separation employing magnetic beads coupled to antibodies. Addition of recombinant TGF-beta or recombinant human IL-10 reduced L. amazonensis-induced cytotoxicity by 90% and 70%, respectively. Cytotoxicity of antigen-stimulated PBMC was also demonstrated against autologous L. amazonensis antigen-pulsed macrophages in the range of 6.7 to 41.7 LU/10(6) PBMC.(ABSTRACT TRUNCATED AT 250 WORDS)

Transforming growth factor-beta in tegumentary leishmaniasis

1. The course of infection with the protozoan parasite Leishmania is determined in part by its early replication in macrophages, the exclusive host cells for these organisms. Resistance to and recovery from leishmanial infection is related to cell-mediated immune responses in all forms of human and murine leishmaniasis. 2. Factors contributing to the early inhibition or proliferation of Leishmania are poorly understood, but cytokines such as IFN gamma, IL-10 or transforming growth factor beta (TGF-beta) are known to influence the replication of Leishmania in macrophages. 3. TGF-beta is a multipotential cytokine with diverse effects on cells of the immune system, including down-regulation of certain macrophage functions. Infection of murine or human macrophages by Leishmania induces the production of active TGF-beta. Recombinant TGF-beta added to murine or human macrophage cultures leads to increased intracellular replication of Leishmania. Exogenous TGF-beta administered in vivo promotes enhancement of infection, whereas its neutralization by monoclonal antibodies decreases the level of in vitro infection, and protects susceptible mice. 4. Susceptible animals treated with anti-TGF-beta monoclonal antibodies change their immune response, not increasing the expression of IL-4 while increasing the expression of IFN gamma mRNA in their draining lymph nodes. Resistant animals treated with TGF-beta also change their pattern of immune response as indicated by an increase of the important Th2 cytokine IL-10 mRNA in the draining lymph node. 5. TGF-beta has profound effects on the host response to Leishmania in both mouse and man, and probably is an important parasite escape mechanism.

Aggravation of both Trypanosoma cruzi and murine leukemia virus by concomitant infections

Given the dissemination of acquired immunodeficiency syndrome (AIDS) in Latin America, where Chagas' disease is endemic, there is a present and increasing risk of concurrent infections with human immunodeficiency virus (HIV) and Trypanosoma cruzi. We used the model of murine acquired immunodeficiency syndrome (MAIDS) caused by a murine leukemia virus (MuLV) that induces immunologic alterations with similarities to those accompanying human HIV infection to study aspects of concomitant infections. The MuLV infection was found to reactivate T. cruzi infection in C57Bl/10 mice, as indicated by elevated parasitemia and lymphocytic infiltration in the myocardium. The T cells from these animals did not respond to T. cruzi antigens (lymphocyte proliferation, interferon-gamma, or interleukin-2 [IL-2] production) but had increased levels of IL-10. Trypanosoma cruzi-specific antibody was decreased but not absent in dually infected animals. In a second set of experiments, we infected MAIDS-resistant B6D2 mice with MuLV, followed by infection with T. cruzi. These animals had higher parasitemia than those infected with T. cruzi alone. More interestingly, only dually infected animals developed MAIDS. The present report describes the activation of T. cruzi infection by MuLV as well as the aggravation of MuLV infection by T. cruzi. These results may be relevant to coinfections with retrovirus and protozoan parasites in humans.

Antigen-reactive gamma delta T cells in human leishmaniasis

The importance of Ag-specific gamma delta T lymphocytes in human immune responses to pathogenic organisms is unknown. In the present study the expression of gamma delta TCR on T lymphocytes from patients with cutaneous, mucosal, or visceral leishmaniasis was examined. All of these patient groups had elevated levels of gamma delta T cells in peripheral blood. Patients' gamma delta T cells included CD8+ as well as null cells. The percentage of T cells expressing gamma delta TCR was increased significantly by stimulation in vitro with certain parasite Ag. T-cell lines generated by stimulation with promastigote lysates of Leishmania amazonensis or L. braziliensis typically contained 25 to 60% gamma delta T cells. In contrast, two immunodominant surface Ag of L. amazonensis, gp63 and gp42, did not expand gamma delta T cells from infected patients, although both Ag elicited strong alpha beta T-cell responses. gamma delta T cells isolated from a Leishmania-specific T-cell line responded to stimulation with promastigote lysate. Of particular interest, gamma delta T cells from PBMC of a patient with mucosal leishmaniasis responded to stimulation with a recombinant 70 kDa heat shock protein of L. chagasi. This study demonstrated that several clinical forms of leishmaniasis induced elevated numbers of gamma delta T cells that responded specifically to Leishmania Ag in vitro. Therefore, this component of the T-cell response to Leishmania may impact the outcome of clinical disease.

Antigen-reactive gamma delta T cells in human leishmaniasis

The importance of Ag-specific gamma delta T lymphocytes in human immune responses to pathogenic organisms is unknown. In the present study the expression of gamma delta TCR on T lymphocytes from patients with cutaneous, mucosal, or visceral leishmaniasis was examined. All of these patient groups had elevated levels of gamma delta T cells in peripheral blood. Patients' gamma delta T cells included CD8+ as well as null cells. The percentage of T cells expressing gamma delta TCR was increased significantly by stimulation in vitro with certain parasite Ag. T-cell lines generated by stimulation with promastigote lysates of Leishmania amazonensis or L. braziliensis typically contained 25 to 60% gamma delta T cells. In contrast, two immunodominant surface Ag of L. amazonensis, gp63 and gp42, did not expand gamma delta T cells from infected patients, although both Ag elicited strong alpha beta T-cell responses. gamma delta T cells isolated from a Leishmania-specific T-cell line responded to stimulation with promastigote lysate. Of particular interest, gamma delta T cells from PBMC of a patient with mucosal leishmaniasis responded to stimulation with a recombinant 70 kDa heat shock protein of L. chagasi. This study demonstrated that several clinical forms of leishmaniasis induced elevated numbers of gamma delta T cells that responded specifically to Leishmania Ag in vitro. Therefore, this component of the T-cell response to Leishmania may impact the outcome of clinical disease.

Transforming growth factor beta as a virulence mechanism for Leishmania braziliensis

Transforming growth factor beta (TGF-beta) has potent down-regulating effects on macrophages and is thus capable of influencing the fate of intramacrophage parasites, including leishmanias. We report the development of a mouse model for the study of the human pathogen Leishmania braziliensis and demonstrate, both in vitro and in vivo, a key regulatory role for TGF-beta in the pathogenesis of infection with this parasite. Recombinant TGF-beta added to cultures of murine peritoneal macrophages led to increased intracellular L. braziliensis replication, whereas addition of neutralizing anti-TGF-beta monoclonal antibody decreased levels of infection. Macrophages infected with L. braziliensis produced biologically active TGF-beta, with a direct correlation between amounts of TGF-beta induced by two parasite isolates and their relative virulence. In vivo, treatment with recombinant TGF-beta rendered avirulent parasites virulent and activated latent L. braziliensis infection. Activation of parasite replication was observed in mice which had been infected with L. braziliensis 15 weeks previously but had not developed lesions or had healed lesions, depending on the parasite isolate used to infect the mice. The exacerbation of L. braziliensis infection in vivo was associated with an increase of interleukin 10 mRNA in the draining lymph node. These results demonstrate that TGF-beta is able to alter the course of in vitro and in vivo infections with L. braziliensis, the latter being characterized by an increase in interleukin 10, an important Th2 helper-T-cell cytokine.

Lymphadenopathy associated with Leishmania braziliensis cutaneous infection

Lymph node involvement by Leishmania during human cutaneous leishmaniasis was reported more than 90 years ago, but the importance of certain Leishmania strains in such dissemination remains largely speculative. We have examined 36 consecutively untreated cutaneous leishmaniasis patients early in their disease; 66.7% had enlarged lymph nodes. Patients with enlarged lymph nodes had higher anti-Leishmania immune responses than patients without such involvement, both at the IgG antibody level (mean +/- SD optical density at 492 nm = 0.163 +/- 0.089 versus 0.098 +/- 0.086; P = 0.009) and in skin test responses (12.4 +/- 10.2 mm versus 5.7 +/- 7.3; P = 0.03). Thirteen (62%) of 21 lymph node cultures and 16 (53%) of 30 cultures from cutaneous sites were positive for Leishmania. Eleven of 13 isolates from lymph nodes were characterized by a panel of monoclonal antibodies, and all were typed as L. braziliensis. Our findings stress the importance of L. braziliensis as an agent involved in the early invasion of the lymphatic system.

Diffuse cutaneous leishmaniasis with atypical aspects

A 16-year-old man had long-standing diffuse cutaneous leishmaniasis with the following characteristics: diffuse infiltrated lesions rich in amastigotes, absence of mucosal involvement, and lack of parasite-specific cell-mediated immune response. In situ identification of Leishmania mexicana amazonensis was achieved by the use of monoclonal antibodies. Clinically, as an atypical finding there was deep and extensive ulceration in the lower limbs. Histologically, an atypical characteristic was the presence of a high number of eosinophils in the infiltrate predominantly in the ulcerated lesion. Ultrastructurally, parasitized and lysed eosinophils with dispersion of their granules were seen in the vicinity of parasitized or lysed macrophages.

Transforming growth factor-beta in leishmanial infection: a parasite escape mechanism

The course of infection with the protozoan parasite Leishmania is determined in part by their early replication in macrophages, the exclusive host cells for these organisms. Although factors contributing to the survival of Leishmania are not well understood, cytokines influence the course of infection. Transforming growth factor-beta (TGF-beta) is a multipotential cytokine with diverse effects on cells of the immune system, including down-regulation of certain macrophage functions. Leishmanial infection induced the production of active TGF-beta, both in vitro and in vivo. TGF-beta was important for determining in vivo susceptibility to experimental leishmanial infection.