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

Cytokine mRNA expression and proliferative responses induced by pertussis toxin, filamentous hemagglutinin, and pertactin of Bordetella pertussis in the peripheral blood mononuclear cells of infected and immunized schoolchildren and adults

Pertussis infection is increasingly recognized in older children and adults, indicating the need of booster immunizations in these age groups. We investigated the induction of pertussis-specific immunity in schoolchildren and adults after booster immunization and natural infection. The expression of mRNA of gamma interferon (IFN-gamma), interleukin-2 (IL-2), IL-4, and IL-5 in the peripheral blood mononuclear cells (PBMCs) was assayed by reverse transcription-PCR. The PBMCs of 17 children immunized with one dose of an acellular vaccine containing pertussis toxin (PT), filamentous hemagglutinin (FHA), and pertactin (PRN) significantly proliferated in vitro after stimulation with the vaccine antigens. The PBMCs of seven infected individuals markedly proliferated in the presence of PT and FHA, but the cells of only two of these subjects responded to PRN. At least one of the antigens induced mRNA for IL-4 and/or IL-5 in the cells of 93% of tested vaccinees and patients, and FHA induced IFN-gamma mRNA in the cells of two-thirds of them. Expression of mRNA for IFN-gamma correlated with the production of the cytokine protein. Anti-FHA immunoglobulin G antibodies significantly correlated with FHA-induced proliferative responses both before and after immunization. These results show that booster immunization with acellular pertussis vaccine induces both antibody- and cell-mediated immune responses in schoolchildren. Further, booster immunization and natural infection seem to induce the expression of mRNA of T-helper 1 (Th1) and Th2 type cytokines in similar manners. This observation supports the use of acellular pertussis vaccines for booster immunizations of older children, adolescents, and adults.

Genetics of host resistance and susceptibility to intramacrophage pathogens: a study of multicase families of tuberculosis, leprosy and leishmaniasis in north-eastern Brazil

Genetic analysis of disease phenotypes segregating in recombinant inbred, congenic and recombinant haplotype mouse strains permitted us to effectively "scan" the murine genome for genes controlling resistance and susceptibility to leishmanial infections. Five major regions were implicated which, because they show conserved synteny with regions of the human genome, immediately provide candidate gene regions for human disease susceptibility genes. A common intramacrophage niche for leishmanial and mycobacterial pathogens, and a similar spectrum of immune response and disease phenotypes, also led to the prediction that the same genes/candidate gene regions might be responsible for genetic susceptibility to mycobacterial infections such as leprosy and tuberculosis. Indeed, one of the murine genes (Nramp1) was identified for its role in controlling a range of intramacrophage pathogens, including leishmanial, salmonella and mycobacterial infections. In recent studies, multicase families of visceral leishmaniasis, tuberculosis and leprosy, from north-eastern Brazil have been analysed to determine the role of these candidate genes/regions in humans. Complex segregation analysis provides evidence for one or two major genes controlling susceptibility to these diseases in this population. Family-based linkage analyses (e.g., combined segregation and linkage analysis; sib-pair analyses) and transmission disequilibrium testing have been used to examine the role of four regions in disease susceptibility and/or immune response phenotypes. Results to date demonstrate: (1) the major histocompatibility complex (MHC:H-2 in mouse, HLA in humans: mouse chromosome 17/human 6p; candidates class II and class III including tumour necrosis factor alpha/beta genes) shows both linkage to, and allelic association with, leprosy per se, but is only weakly associated with visceral leishmaniasis and shows neither linkage to, nor allelic association with, tuberculosis; (2) no evidence for linkage between NRAMP1, the positionally cloned candidate for the murine macrophage resistance gene Ity/Lsh/Bcg (mouse chromosome 1/human 2q35), and susceptibility to tuberculosis or visceral leishmaniasis; (3) the region of human chromosome 17q (candidates NOS2A, SCYA2-5) homologous with distal mouse chromosome 11 is linked to tuberculosis susceptibility; and (4) the "T helper 2" cytokine gene cluster (proximal murine chromosome 11/human 5p; candidates IL4, IL5, IL9, IRF1, CD14) is not linked to human disease susceptibility for any of the three infections, but shows linkage to and highly significant allelic association with ability to mount an immune response to mycobacterial antigens. The demonstration of an allelic association between IL4 and immune response to mycobacterial antigen may provide a genetic explanation for the inverse association recently demonstrated between delayed hypersensitivity T helper 1 responses to mycobacterial antigen and atopic disorder in Japanese children. These studies demonstrate that the "mouse-to-human" strategy, refined by our knowledge of the human immune response to infection, can lead to the identification of important candidate gene regions in humans.

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.

T cell responses to crude and defined leishmanial antigens in patients from the lower Amazon region of Brazil infected with different species of Leishmania of the subgenera Leishmania and Viannia

Amazonian localized cutaneous leishmaniasis (LCL) is caused by parasites of the subgenera Leishmania and Viannia. Respectively, these parasites may cause diffuse cutaneous leishmaniasis (DCL) and mucocutaneous leishmaniasis (MCL). This, together with differing skin test responses, suggests some species-specificity in cell mediated immunity. In this study, T cell responses (proliferative and interferon-gamma) to crude and defined antigens were examined in paired samples pre and post chemotherapy. Untreated L. (L.) amazonensis LCL patients showed lower responses to crude leishmanial antigens than the L. (V.) spp. group. L. (V.) braziliensis antigen was a more potent stimulator of T cell responses than L. (L.) amazonensis antigen in all patient groups. Few positive responses were seen to the L. (L.) amazonensis glycoprotein GP46. A substantial proportion of LCL patients did respond to the L. (L.) pifanoi amastigote antigens A2, and the surface membrane glycoprotein P8. DCL patients were poor responders to all leishmanial antigens, except GP46. In contrast, MCL patients were good responders to all antigens except GP46 and A2. A significant rise in the response to P8 and A2 antigen was seen post treatment across all LCL and MCL patients, indicating that these antigens might provide suitable vaccine candidates.

Cytokine profile and pathology in human leishmaniasis

The clinical spectrum of leishmaniasis and control of the infection are influenced by the parasite-host relationship. The role of cellular immune responses of the Th1 type in the protection against disease in experimental and human leishmaniasis is well established. In humans, production of IFN-gamma is associated with the control of infection in children infected by Leishmania chagasi. In visceral leishmaniasis, an impairment in IFN-gamma production and high IL-4 and IL-10 levels (Th2 cytokines) are observed in antigen-stimulated peripheral blood mononuclear cells (PBMC). Moreover, IL-12 restores IFN-gamma production and enhances the cytotoxic response. IL-10 is the cytokine involved in down-regulation of IFN-gamma production, since anti-IL-10 monoclonal antibody (mAb) restores in vitro IFN-gamma production and lymphoproliferative responses, and IL-10 abrogates the effect of IL-12. In cutaneous and mucosal leishmaniasis, high levels of IFN-gamma are found in L. amazonensis-stimulated PBMC. However, low or absent IFN-gamma levels were observed in antigen-stimulated PBMC from 50% of subjects with less than 60 days of disease (24 +/- 26 pg/ml). This response was restored by IL-12 (308 +/- 342 pg/ml) and anti-IL-10 mAb (380 +/- 245 pg/ml) (P < 0.05). Later during the disease, high levels of IFN-gamma and TNF-alpha are produced both in cutaneous and mucosal leishmaniasis. After treatment there is a decrease in TNF-alpha levels (366 +/- 224 pg/ml before treatment vs 142 +/- 107 pg/ml after treatment, P = 0.02). Although production of IFN-gamma and TNF-alpha might be involved in the control of parasite multiplication in the early phases of Leishmania infection, these cytokines might also be involved in the tissue damage seen in tegumentary leishmaniasis.

Association of Leishmania heat shock protein 83 antigen and immunoglobulin G4 antibody titers in Brazilian patients with diffuse cutaneous leishmaniasis

Diffuse cutaneous leishmaniasis (DCL) is characterized by the presence of numerous nonulcerated nodules and plaques containing large numbers of Leishmania amazonensis parasites and few lymphoid elements. The immune responses of DCL patients reflect severe antigen-specific T-cell deficiencies, while the antibody response to Leishmania antigens is often accentuated. We report herein on the Leishmania antigen-specific antibody subclass distribution in DCL patients and demonstrate that a dominant antigen contributing to the biased immunoglobulin G4 antibody subclass in sera of DCL patients is Leishmania heat shock protein 83.

Immunogenetics of leishmanial and mycobacterial infections: the Belem Family Study

In the 1970s and 1980s, analysis of recombinant inbred, congenic and recombinant haplotype mouse strains permitted us to effectively 'scan' the murine genome for genes controlling resistance and susceptibility to leishmanial infections. Five major regions of the genome were implicated in the control of infections caused by different Leishmania species which, because they show conserved synteny with regions of the human genome, immediately provides candidate gene regions for human disease susceptibility genes. A common intramacrophage niche for leishmanial and mycobacterial pathogens, and a similar spectrum of immune response and disease phenotypes, also led to the prediction that the same genes/candidate gene regions might be responsible for genetic susceptibility to mycobacterial infections such as leprosy and tuberculosis. Indeed, one of the murine genes (Nramp1) was identified for its role in controlling a range of intramacrophage pathogens including leishmania, salmonella and mycobacterium infections. In recent studies, multicase family data on visceral leishmaniasis and the mycobacterial diseases, tuberculosis and leprosy, have been collected from north-eastern Brazil and analysed to determine the role of these candidate genes/regions in determining disease susceptibility. Complex segregation analysis provides evidence for one or two major genes controlling susceptibility to tuberculosis in this population. Family-based linkage analyses (combined segregation and linkage analysis; sib-pair analysis), which have the power to detect linkage between marker loci in candidate gene regions and the putative disease susceptibility genes over 10-20 centimorgans, and transmission disequilibrium testing, which detects allelic associations over 1 centimorgan (ca. 1 megabase), have been used to examine the role of four regions in determining disease susceptibility and/or immune response phenotype. Our results demonstrate: (i) the major histocompatibility complex (MHC: H-2 in mouse, HLA in man: mouse chromosome 17/human 6p; candidates class II and class III including TNF alpha/beta genes) shows both linkage to, and allelic association with, leprosy per se, but is only weakly associated with visceral leishmaniasis and shows neither linkage to nor allelic association with tuberculosis; (ii) no evidence for linkage between NRAMP1, the positionally cloned candidate for the murine macrophage resistance gene Ity/Lsh/Bcg (mouse chromosome 1/human 2q35), and susceptibility to tuberculosis or visceral leishmaniasis could be demonstrated in this Brazilian population; (iii) the region of human chromosome 17q (candidates NOS2A, SCYA2-5) homologous with distal mouse chromosome 11, originally identified as carrying the Scl1 gene controlling healing versus nonhealing responses to Leishmania major, is linked to tuberculosis susceptibility; and (iv) the 'T helper 2' cytokine gene cluster (proximal murine chromosome 11/human 5q; candidates IL4, IL5, IL9, IRF1, CD14) controlling later phases of murine L. major infection, is not linked to human disease susceptibility for any of the three infections, but shows linkage to and highly significant allelic association with ability to mount an immune response to mycobacterial antigens. These studies demonstrate that the 'mouse-to-man' strategy, refined by our knowledge of the human immune response to infection, can lead to the identification of important candidate gene regions in man.

Relationship among circulating interferon, tumor necrosis factor-alpha, and interleukin-6 and serologic reaction against parasitic antigen in human hydatidosis

Human hydatidosis is a parasitic disease vectored by the larval stage cestode Echinoccocus granulosus. It constitutes a major health problem in North Africa. We investigated the production of circulating interferon (IFN), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) in Algerian patients with liver, lung, or ocular hydatidosis. In all, 101 serum samples from these patients with analyzed. Immunoreactivity and cytokine activities were undetectable in sera from ocular hydatidosis patients. However, we observed the presence of IFN (a mixture of IFN-alpha, IFN-beta, and IFN-gamma, range 32-500 U/ml), TNF-alpha (range 32-100 U/ml), and IL-6 (range 32-500 U/ml) in all patients who had liver or lung cysts or both and displayed immunoreactivity against parasitic antigen (antigen 5). After surgical removal of the cysts, serum cytokine levels declined rapidly and were undetectable at 30 days. IFN and IL-6 activity was undetectable in sera from two liver hydatidosis patients who relapsed and did not display any immune response against parasitic antigen. These results suggest that in liver and lung hydatidosis, cytokine production contributes to the host defense mechanism against the extracellular parasite.

Immune responses induced by a Leishmania (Leishmania) amazonensis recombinant antigen in mice and lymphocytes from vaccinated subjects

In the search for Leishmania recombinant antigens that can be used as a vaccine against American Cutaneous Leishmaniasis, we identified a Leishmania (Leishmania) amazonensis recombinant protein of 33 kD (Larp33) which is recognized by antibodies and peripheral blood leukocytes (PBL) from subjects vaccinated with Leishvacin, Larp33 was expressed in Escherichia coli after cloning of a 2.2 kb Sau3 digested genomic fragment of L. (L.) amazonensis into the pDS56-6 His vector. Immunoblotting analysis indicated that Larp33 corresponds to an approximately 40-kD native protein expressed in promastigotes of L. (L.) amazonensis and L. (Viannia) braziliensis. Northern blots of total RNA also demonstrated that the gene coding for this protein is expressed in promastigotes of the major lineages of Leishmania causing American Cutaneous Leishmaniasis. Larp33 induced partial protection in susceptible mouse strains (BALB/c and C57BL/10) against L. (L.) amazonensis after vaccination using Bacille Calmette-Guerin (BCG) as adjuvant. In vitro stimulation of splenocytes from BALB/c protected mice with Larp33 elicited the secretion of IL-2 and IFN-gamma, suggesting that a Th1 cell-mediated protective response is associated with the resistance observed in these mice. As revealed by its immunogenic and antigenic properties, this novel recombinant antigen is a suitable candidate to compose a vaccine against cutaneous leishmaniasis.

Expression of mRNA for interferon-gamma, interleukin-10, and interleukin-12 (p40) in normal gastric mucosa and in mucosa infected with Helicobacter pylori

BACKGROUND

We studied the mRNA expressions of interferon-gamma (IFN-gamma), interleukin-10 (IL-10), and IL-12 in gastric biopsy and blood samples from patients with and without Helicobacter pylori infection, by reverse-transcription polymerase chain reaction (RT-PCR).

METHODS

RT-PCR was performed on total RNA preparations, and the expressed mRNA were semiquantitated on the basis of band intensities on Southern blots.

RESULTS

In gastric mucosa the expression of IFN-gamma and IL-10 was found in most patients with and without H. pylori infection, whereas IL-12 was found in most of the infected ones. The level of IFN-gamma and IL-10 did not differ between groups, whereas the IL-12 level was significantly higher in those with H. pylori infection. In the blood IFN-gamma expression was found in most samples, with higher level in patients with gastritis than in normals. Few blood samples (33%) had IL-12, and none had IL-10.

CONCLUSION

IFN-gamma and IL-10 expressions in healthy mucosa may indicate a biologic role in a healthy state. IL-12 expression in mucosa was related to the presence of bacterial stimulant and therefore resembles proinflammatory cytokines.

Interleukin-10 induces E-selectin on small and large blood vessel endothelial cells

In vitro, expression of E-selectin is largely restricted to endothelial cells activated by inflammatory cytokines. Under activated conditions, cytokines such as interleukin (IL) 10, released by keratinocytes in large quantities, may also increase the expression of E-selectin on the dermal microvasculature. The aim of the present study was to investigate the expression of E-selectin on cultured human dermal microvascular endothelial cells (HDMEC) isolated from neonatal foreskins when exposed to IL-10. Expression of E-selectin was determined by immunofluorescence microscopy, FACS analysis, an HL-60 cell-binding assay, and quantitative polymerase chain reaction (PCR) analysis. For comparison with large blood vessel cells, the expression of E-selectin on human umbilical vein endothelial cells (HUVEC) was also determined in parallel by FACS and reverse transcriptase-PCR analysis under identical conditions. These studies demonstrate that IL-10 induces the expression of E-selectin on both HDMEC and HUVEC and that the level of expression of HDMEC is comparable with that induced by IL-1 beta and tumor necrosis factor-alpha. When HL-60 cells are incubated with HDMEC pretreated with IL-10, a consistent increase in adherence of HL-60 to endothelial cells is observed. This adherence was found to be mediated by L-selectin. PCR analysis and the quantification of E-selectin cDNA by a novel, highly sensitive and specific PCR-immunoassay demonstrate the induction of E-selectin mRNA at the transcriptional level. The induction of the expression of E-selectin by IL-10 on HDMEC may provide additional insights into the pathogenic mechanism of neutrophil accumulation at the site of inflammation in inflammatory skin diseases.

In situ expression of interleukin-10 and interleukin-12 in active human cutaneous leishmaniasis

Th1-type cellular immune responses (interferon-gamma) play a critical role in protection against Leishmania spp. infection, whereas Th2-type cytokines (interleukin (IL)-4, IL-10) have a counter-protective effect. IL-12, a potent inducer of Th1-type cellular immune responses, may play a pivotal role in the development of a protective response. We found that IL-10 and IL-12 mRNAs were expressed in most lesions of individuals with active cutaneous leishmaniasis. The quantity of IL-12 mRNA was highly variable but correlated strongly with the level of interferon-gamma expression. IL-12 expression also paralleled the expression of IL-10, a potent in vitro suppressor of IL-12 and interferon-gamma production. The more chronic, non-healing lesions generally had higher levels of IL-12 mRNA indicating that the expression of this cytokine alone was not sufficient to induce healing. Although the in situ production of IL-10 did not appear to block IL-12 expression, IL-10 may still promote disease by direct suppression of macrophage activation.

Cytokines and inflammatory bowel disease

Cytokines play an important role in the pathology of inflammatory bowel disease by determining the nature of the mucosal immune response. One way of establishing whether CD and UC are causally related to a defect in the host immune response is to look for polymorphisms that are over-represented in these populations. This is being carried out at great pace both for the cytokine genes and for some other immune response genes. A number of gene expression studies have established that those cytokines produced by activated macrophages such as IL-1, IL-6 and TNF are significantly elevated in both diseases. Differences between the two diseases are less clear, and, where they have been found, they probably reflect the accuracy and sensitivity of quantification. The picture is less clear for the T-cell-derived cytokines, which are generally expressed at a lower copy number in intestinal tissue compared to the monokines. For Crohn's disease, the TH1 cytokines IL-2 and IFN may be abnormally elevated or decreased. In contrast, the TH1/TH2 profile in UC is not significantly different from normal controls. Further work is required to confirm these findings.

Tumor necrosis factor-alpha in human american tegumentary leishmaniasis

Tumor necrosis factor-alpha (TNF-alpha) is a cytokine produced by activated macrophages and other cells. In order to verify whether the serum levels of TNF-alpha in American tegumentary leishmaniasis patients are associated with the process of cure or aggravation of the disease, 41 patients were studied: 26 cases of cutaneous leishmaniasis (CL) and 15 of mucocutaneous leishmaniasis (MCL). During active disease the serum levels of TNF-alpha of MCL patients were significantly higher than those of CL patients and control subjects (healthy individuals and cutaneous lesions from other etiologies). The MCL patients had serum titers of TNF-alpha significantly lower at the end of antimonial therapy than before therapy. After a six-month follow-up, the MCL patients had serum levels of TNF-alpha similar to those observed at the end of the therapy as well as to those of CL patients and control subjects. No significant variation in the serum levels of TNF-alpha was observed in CL patients throughout the study period (before, at the end of therapy and after a six-month follow-up). The possible relationship between the high TNF-alpha serum levels and severity of the disease is discussed.

Disruption of the murine interleukin-4 gene inhibits disease progression during Leishmania mexicana infection but does not increase control of Leishmania donovani infection

The growths of both cutaneous leishmaniasis and visceral leishmaniasis caused by Leishmania mexicana and Leishmania donovani, respectively, were measured in interleukin-4 (IL-4) knockout mice (IL-4-/-) and compared with those of similarly infected wild-type (IL-4+/+) control mice. While large, nonhealing, cutaneous lesions containing large numbers of parasites developed in IL-4+/+ mice subcutaneously infected with 5 x 10(6) L. mexicana amastigotes in the shaven rump, in IL-4-/- mice no lesions whatsoever developed and parasites were difficult to detect. Systemic spread and metastasis were also noted in IL-4+/+ but not IL-4-/- mice. In contrast, IL-4-/- mice infected intravenously with 10(7) L. donovani amastigotes were found to have consistently higher parasite burdens in their livers throughout infection than did their wild-type counterparts. However, these differences were only significant at 15 days postinfection. While the results reported here pertaining to L. donovani largely support previous studies, those related to L. mexicana provide new observations. The immunological responses of IL-4-/- and IL-4+/+ mice infected with L. mexicana were, therefore, examined both in vivo and in vitro. Although neither IL-4-/- nor IL-4+/+ mice infected with L. mexicana produced parasite-specific immunoglobulin G2a antibodies, IL-4+/+ mice, unlike IL-4-/- mice, developed significant immunoglobulin G1 antibody titers as infection progressed, indicating a Th2-influenced response in wild-type mice. In addition, IL-4-/- mice, unlike IL-4+/+ mice, developed a significant delayed-type hypersensitivity response, indicating a Th1-influenced response in IL-4-/- mice. Following in vitro stimulation, splenocytes from IL-4+/+ mice infected with L. mexicana displayed significantly higher antigen-specific proliferative responses than did IL-4-/- mice. However, gamma interferon production as measured from the supernatants of the in vitro splenocyte cultures of IL-4-/- mice was significantly higher than that from IL-4+/+ mice. This again would indicate a predominantly Th1-influenced response in the absence of a Th2 response in IL-4-/- mice infected with L. mexicana. On the other hand, at the same time point, draining lymph node cells from IL-4+/+ mice produced significantly higher quantities of IL-5 than did those from IL-4-/- mice following in vitro antigenic stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

Polymorphism in tumor necrosis factor genes associated with mucocutaneous leishmaniasis

Recent studies have shown that mucocutaneous leishmaniasis (MCL), a severe and debilitating form of American cutaneous leishmaniasis (ACL) caused by Leishmania braziliensis infection, is accompanied by high circulating levels of tumor necrosis factor (TNF)-alpha. Analysis of TNF polymorphisms in Venezuelan ACL patients and endemic unaffected controls demonstrates a high relative risk (RR) of 7.5 (P < 0.001) of MCL disease in homozygotes for allele 2 of a polymorphism in intron 2 of the TNF-beta gene, especially in females (RR = 9.5; P < 0.001) compared with males (RR = 4; P < 0.05). A significantly higher frequency (P < 0.05) of allele 2 at the -308-basepair TNF-alpha gene polymorphism was also observed in MCL patients (0.18) compared with endemic control subjects (0.069), again associated with a high relative risk of disease (RR = 3.5; P < 0.05) even in the heterozygous condition. Because both the TNF-alpha and TNF-beta polymorphisms have previously been linked with functional differences in TNF-alpha levels, these data suggest that susceptibility to the mucocutaneous form of disease may be directly associated with regulatory polymorphisms affecting TNF-alpha production.

Detection of cytokine transcriptional profiles from bovine peripheral blood mononuclear cells and CD4+ lymphocytes by reverse transcriptase polymerase chain reaction

Cytokine transcriptional profiles constitute important information about T cell mediated immunity against pathogens. We have developed a reverse transcriptase polymerase chain reaction (RT-PCR) assay to monitor gene expression of bovine T lymphocyte cytokines. Bovine cDNA was reverse transcribed from total RNA and subsequently amplified using primers designed from bovine or murine and human consensus sequences. Cytokine transcription of beta-actin, interleukins (IL) IL-1 alpha, IL-1 beta, IL-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF)alpha, TNF beta and interferon-gamma was detected from concanavalin A activated peripheral blood mononuclear cells and CD4+ purified T lymphocytes. The assay allows detection of many cytokine mRNA in a species where research has been hindered by lack of commercially available reagents and sequence information. RT-PCR analysis of lymphocyte cytokines will be invaluable for understanding the progression or resolution of disease as a consequence of lymphocyte response to specific antigens.

Differential correlation between interleukin patterns in disseminated and chronic human paracoccidioidomycosis

In an attempt to understand better the immunoregulatory disorders in paracoccidioidomycosis (PCM), the possible correlation between interleukin pattern, lymphoproliferation, C-reactive protein (CRP) and specific antibody levels was investigated in the polarized clinical forms of this disease. We studied 16 PCM patients, eight with the disseminated disease (four under treatment and four non-treated) and eight with the chronic disease. The patients with disseminated disease exhibited high antibody titres specific to Paracoccidioides brasiliensis antigen compared with patients with the chronic form of disease. Tumour necrosis factor (TNF), IL-1, IL-6 and CRP in the serum of non-treated disseminated PCM patients were increased, which correlated positively with the low mitogenic response of peripheral blood mononuclear cells (PBMC) to phytohaemagglutinin (PHA) (P < 0.01) and with the high antibody titres (P < 0.001) of these patients. Moreover, we found in the disseminated PCM patients positive correlations between IL-1 and IL-6 (P = 0.0007); IL-1 and TNF (P = 0.0045); IL-1 and IL-6 with the high antibody titres (P = 0.0834 and P = 0.0631, respectively); IL-1, IL-6 and TNF with CRP levels. By contrast, no correlations were found with those interleukins in the treated disseminated and chronic patients or in controls. It was interesting to find an inverse correlation between IL-4 and antibody production in non-treated disseminated PCM (r = -0.4770); moreover, a significant correlation (P = 0.0820) was found in chronic PCM patients with respect to the low level of either IL-4 and antibody titres against fungus antigen. Chronic PCM patients also had IL-2 levels inversely correlated with antibody production (r = -0.6313; P = 0.0628). Inverse correlations were also observed between IL-2 and IL-6 levels in non-treated disseminated patients (P = 0.0501) and between IL-2 and IL-4 in chronic patients (P = 0.0131). The inflammatory cytokines might have a pivotal role in the genesis and in control of some aspects of the disease, such as granulomatous reaction, hypergammaglobulinaemia and depression of T cell-mediated immunity in PCM.

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.

IL-4 mRNA expression by peritoneal cells during episodes of peritonitis in patients on continuous ambulatory peritoneal dialysis

Peritoneal cells were isolated from dialysates drained from nine patients on continuous ambulatory peritoneal dialysis (CAPD) during episodes of peritonitis. Levels of expression of mRNA for the regulatory cytokines, interferon-gamma (IFN-gamma) and IL-4, were investigated daily, where possible, during the first 5 days of peritonitis. Cytokine mRNA levels were compared with those of peripheral blood mononuclear cells (PBMC) stimulated in vitro with phorbol 12-myristate 13-acetate (PMA) plus phytohaemagglutinin (PHA). Peritoneal cells expressed low levels of IFN-gamma mRNA; for four of nine patients, IL-4 mRNA levels greater than those expressed by stimulated PBMC were detected. There was no pattern of cytokine mRNA expression associated with the types of organisms detected in dialysates at initiation of peritonitis. However, in contrast to those patients with a transient, resolving peritonitis, significant IL-4 mRNA expression was detected in cells isolated early in the episodes of peritonitis in patients who suffered recurrent peritonitis within 30 days of the initial peritonitis episode. These results suggest an association between early IL-4 mRNA expression and susceptibility to further infections. The known anti-inflammatory effects of IL-4 may explain this association.

Dichotomy of the T cell response to Leishmania antigens in patients suffering from cutaneous leishmaniasis; absence or scarcity of Th1 activity is associated with severe infections

The T cell response was studied in 25 patients suffering from cutaneous leishmaniasis caused by Leishmania major with severe (n = 10) and mild (n = 15) disease manifestations. Peripheral blood mononuclear cells (PBMC) from the patients were activated by sonicates of Leishmania promastigotes (LMP) and amastigotes (LDA), and the surface protease gp63. The proliferative responses to Leishmania antigens were lower in patients with severe disease than in patients with mild disease (P = 0.01-0.05), and such a difference was not observed in the response to purified protein derivative of tuberculin (PPD) or tetanus toxoid (TT). LMP-induced interferon-gamma (IFN-gamma) production was lower in patients with severe than in patients with mild disease (P < 0.05). When the IL-4 and IFN-gamma responses of each patient were considered, two response patterns were observed in the cultures activated by the Leishmania sonicates. One response pattern was characterized by high production of IFN-gamma without production of IL-4 (a Th1-like pattern), the other was characterized by low IFN-gamma levels which in most cases were associated with IL-4 production (not a Th1-like pattern). These patterns could not be distinguished when the cells from the same donors were stimulated by TT and PPD. The percentages of patients with a Th1-like response pattern after stimulation by LMP in patients with severe and mild disease manifestations were 30% and 80%, respectively. This difference was statistically significant (P = 0.034).

Switch from a type 2 to a type 1 T helper cell response and cure of established Leishmania major infection in mice is induced by combined therapy with interleukin 12 and Pentostam

Successful treatment in allergic, autoimmune, and infectious diseases often requires altering the nature of a detrimental immune response mediated by a particular CD4+ T helper (Th) cell subset. While several factors contribute to the development of CD4+ Th1 and Th2 cells, the requirements for switching an established response are not understood. Here we use infection with Leishmania major as a model to investigate those requirements. We report that treatment with interleukin 12 (IL-12), in combination with the antimony-based leishmanicidal drug Pentostam, induces healing in L. major-infected mice and that healing is associated with a switch from a Th2 to a Th1 response. The data suggest that decreasing antigen levels may be required for IL-12 to inhibit a Th2 response and enhance a Th1 response. These observations are important for treatment of nonhealing forms of human leishmaniasis and also demonstrate that in a chronic infectious disease an inappropriate Th2 response can be switched to an effective Th1 response.

Differing antibody IgG isotypes in the polar forms of leprosy and cutaneous leishmaniasis characterized by antigen-specific T cell anergy

Leprosy and American cutaneous leishmaniasis are tropical diseases which present a spectrum of clinical and immunological manifestations. Lepromatous leprosy and diffuse cutaneous leishmaniasis are the severe, progressive polar forms of disease characterized by persistent T cell anergy. Relative concentrations of antibodies belonging to the four IgG isotypes have been determined in these forms of disease as well as active visceral leishmaniasis, which presents transitory T cell anergy. Leishmania-specific IgG4 antibodies predominated in 19/20 sera from patients with diffuse cutaneous leishmaniasis, and IgG1 antibodies predominated in 9/10 cases of untreated visceral leishmaniasis. The predominant IgG isotype of Mycobacterium leprae-specific antibodies in untreated lepromatous leprosy was remarkably variable (IgG1, IgG2, IgG3 and IgG4 in 8, 6, 2 and 1 sera, respectively). Differing IgG antibody isotypes have been associated with distinct CD4+ T cell helper subpopulations and their characteristic lymphokine profiles in several pathologies. These results suggest that T cell anergy in chronic intracellular infections may be associated with as yet undefined mechanisms which modulate reported T helper cell-lymphokine isotype relationships.

A recombinant Leishmania antigen that stimulates human peripheral blood mononuclear cells to express a Th1-type cytokine profile and to produce interleukin 12

Leishmania braziliensis causes cutaneous and mucosal leishmaniasis in humans. Most patients with cutaneous leishmaniasis heal spontaneously and may therefore have developed protective immunity. There appears to be a mixed cytokine profile associated with active cutaneous or mucosal disease, and a dominant T helper (Th)1-type response associated with healing. Leishmanial antigens that elicit these potent proliferative and cytokine responses from peripheral blood mononuclear cells (PBMC) are now being identified. Herein, we report on the cloning and expression of a L. braziliensis gene homologous to the eukaryotic ribosomal protein eIF4A (LeIF) and patient PBMC responses to rLeIF. Patients with mucosal and self-healing cutaneous disease had significantly higher proliferative responses than those with cutaneous lesions. Whereas the parasite lysate stimulated patient PBMC to produce a mixed Th1/Th2-type cytokine profile, LeIF stimulated the production of interferon gamma (IFN-gamma), interleukin 2 (IL-2), and tumor necrosis factor alpha but not IL-4 or IL-10. Recombinant LeIF (rLeIF) downregulated both IL-10 mRNA in the "resting" PBMC of leishmaniasis patients and LPS-induced IL-10 production by patient PBMC. rLeIF also stimulated the production of IL-12 in cultured PBMC from both patients and uninfected individuals. The production of IFN-gamma by patient PBMC stimulated with either rLeIF or parasite lysate was IL-12 dependent, whereas anti-IFN-gamma monoclonal antibody only partially blocked the LeIF-induced production of IL-12. In vitro production of both IFN-gamma and IL-12 was abrogated by exogenous human recombinant IL-10. Therefore, we have identified a recombinant leishmanial antigen that elicits IL-12 production and Th1-type responses in patients as well as IL-12 production in normal human PBMC.

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)

Immune response in healthy volunteers vaccinated with BCG plus killed leishmanial promastigotes: antibody responses to mycobacterial and leishmanial antigens

Antibody (IgG) responses to mycobacterial (BCG; PPD; Mycobacterium leprae soluble antigen, MLSA) and leishmanial (Leishmania mexicana LV4) antigens were measured in 208 initially PPD and leishmanin skin-test negative volunteers divided into four vaccine groups as follows: 68 received BCG plus killed promastigotes (group A), 47 received BCG alone (group B), 47 received killed promastigotes alone (group C), and 46 formed the diluent control (placebo, group D). Three vaccine doses were administered at 8-12 week intervals. Vaccinees were bled immediately prior to each vaccination, and again at 3- and 12-month follow-up. Skin tests were performed prevaccination, and again at the 3- and 12-month follow-up. Anti-BCG, anti-PPD and anti-MLSA IgG levels increased significantly in groups A and B receiving BCG. The presence of leishmanial antigen (with BCG) in the inoculum suppressed the IgG response to Mycobacterium tuberculosis/Mycobacterium bovis-related (PPD and BCG), but not M. leprae-related (MLSA)-related, antigens. A small but significant increase (relative to prevaccination level) in response to MLSA, but not to BCG or PPD was observed in the non-BCG-vaccinated groups. The background level of response to mycobacterial and leishmanial antigens was higher in the Venezuelan vaccinees than in non-endemic (British) volunteers. Responses to leishmanial antigen were not enhanced in the two vaccine groups receiving killed promastigotes (with/without BCG) compared with the BCG alone and placebo groups. Instead, all vaccine groups showed a pattern of response consistent with either (i) a response to the skin-test antigen or, more likely, (ii) seasonal endemic exposure to leishmanial antigen. Interestingly, this endemic response to leishmanial antigen was enhanced in the vaccine groups receiving BCG, despite the fact that group B received no leishmanial antigen in the vaccine inoculum. When prevaccination IgG levels (mean + 3 standard deviations) were used to determine a negative cut-off, a low percentage (< 38%) of vaccinees converted to responder status for either anti-mycobacterial or anti-leishmanial responses, and those who did would be classified as 'low-responder' status compared with titres observed in severe forms of disease. Hence, although there was evidence for a background endemic response to both leishmanial and mycobacterial antigens, there was no evidence that vaccination per se led to a potentially disease exacerbatory level of TH2-associated antibody response especially with respect to the anti-leishmanial response.(ABSTRACT TRUNCATED AT 400 WORDS)

Cytokines in the treatment of leishmaniasis: from studies of immunopathology to patient therapy

The genus Leishmania, an obligate intramacrophage parasite, causes a wide spectrum of clinical diseases. It is worldwide in distribution and causes 20 million new cases annually with an at risk population of approximately 1.5 billion persons. The most severe forms are associated with high morbidity, mortality and relapses with conventional therapy. The therapeutic issues and responses to standard and alternative therapies are reviewed. Recent developments in molecular biology and immunology methods employed in the study of leishmaniasis have defined an intricate interaction of the parasite with host immune system. Perturbation of the host immune responses may be part of the survival mechanisms of Leishmania. In murine model, the finding of T helper cells that differ by their panel of cytokines has allowed a more precise definition of immunopathogenesis of leishmaniasis. Preliminary data from leishmaniasis patients lend support to this concept of altered immunomodulation. Furthermore, the data from leishmaniasis patients lend support to this concept of altered enhancement of therapeutic response by interferon-gamma has provided a new approach for treatment of patients using recombinant cytokines and for the study of the disease. Current research for early diagnosis, alternative therapies and need for vaccines are reviewed in the context of the immunopathology of leishmaniasis.

Immune response in healthy volunteers vaccinated with killed leishmanial promastigotes plus BCG. I: Skin-test reactivity, T-cell proliferation and interferon-gamma production

This study reports the results of a vaccine trial established to study the cellular immune responses in vivo (skin-test reactivity) and in vitro (T-cell proliferation and interferon-gamma production) to both leishmanial and mycobacterial antigens following vaccination of healthy volunteers from a leishmaniasis-endemic area with killed leishmanial promastigotes, with or without BCG (Bacille Calmètte-Guerin). Skin tests were performed using purified protein derivative of tuberculin (PPD) and leishmanial antigen in 692 volunteers, and 208 doubly negative subjects (< or = 7 mm induration) were selected to participate in the trial. The study subjects were divided into four vaccine groups: (A) killed promastigotes plus BCG, (B) BCG alone, (C) killed promastigotes alone, and (D) placebo. Three vaccine doses were administered at 6-10-week intervals. The skin-test responses to PPD and leishmanial antigen were reassessed at 4-6- and 12-18-month follow-ups. The results of this trial demonstrated that the combined vaccine, i.e. killed promastigotes of Leishmania plus BCG, results in the stimulation of an immune response to both leishmania and mycobacterial antigens in a high percentage of vaccines (> 85%), manifested either by skin-test conversion, lymphocyte proliferation and/or interferon-gamma production. This was evident after the first dose of vaccine for lymphocyte proliferation and interferon-gamma production and was maintained for a year after the three doses of vaccine. Group B (which received BCG alone), responded as well as group A to PPD but not as well to leishmanial antigen. The reverse was true for group C which received promastigotes alone. Group A attained a 38% leishmanin skin-test conversion at the 4-6-month follow-up, which was associated with double PPD/leishmanial antigen responder status. In contrast, a 35% skin-test conversion was found at the 12-18-month follow-up in group C (promastigotes alone), but this was not associated with responses to PPD. A significant percentage of conversion was observed in the placebo group at the 12-18-month follow-up, both to PPD (58%) and leishmanial (21%) antigens, which suggests either environmental exposure to mycobacterial or leishmanial antigens during the vaccine trial or, more probably, a response to the repeated leishmanial skin tests. Further studies are required to determine whether the presence of proliferative and/or interferon-gamma responses in the absence of a skin-test response are sufficient indicators of potential vaccine success.

Th1-Th2 paradigm: insights from leprosy

The mechanism by which T cells and cytokines regulate immune processes in skin can be investigated by studying patients with leprosy. The disease, caused by the obligate intracellular bacterium Mycobacterium leprae, forms a spectrum. At one pole, patients with tuberculoid leprosy are able to restrict the growth of the pathogen and their skin lesions are characterized by a predominance of CD4+ T cells and type 1 cytokines including interleukin 2 and interferon gamma. At the opposite pole, patients with lepromatous leprosy are unable to contain the infection and their skin lesions are characterized by a predominance of CD8+ T cells and type 2 cytokines including interleukins 4 and 10. A key determinant of the T-cell cytokine response may be interleukin 12, which selectively favors expansion of CD4+ T cells producing interferon gamma. By understanding the factors that regulate T-cell and cytokine responses in leprosy, it should be possible to devise specific immunologic interventions in diseases of skin.

Inadequate epidermal homing leads to tissue damage in human cutaneous leishmaniasis

Leishmaniasis is a model disease for the study of immunoregulatory mechanisms associated with host resistance and susceptibility. In this article, Felix Tapia and colleagues propose that defects in the signaling properties of the epidermis can result in the generation of either a chronic granulomatous response, which is unable to eliminate the parasite, or a proinflammatory mucocutaneous response and tissue damage.

Increased expression of proinflammatory cytokines in chronic lesions of human cutaneous leishmaniasis

The nature of the host cellular immune response largely determines the expression of disease following infection with the intracellular protozoans Leishmania spp. In experimental animals control and resolution of infection are mediated by gamma interferon and tumor necrosis factor alpha (TNF-alpha), whereas disease progression is associated with the production of interleukin 4 (IL-4), IL-5, IL-10, and transforming growth factor beta (TGF-beta). We have analyzed the profile of cytokine gene expression directly in the lesions of 13 patients with localized cutaneous leishmaniasis due to Leishmania mexicana. All but one patient had a single lesion, and the time of evolution ranged from 8 days to 18 months. Cytokine gene expression was quantitated by reverse transcriptase PCR and interpolation from a standard curve. Gamma interferon, TNF-alpha, IL-1 alpha, IL-6, IL-10, and TGF-beta gene expression was present in all samples. IL-3 and IL-4 gene expression was barely detectable in 1 and 3 of 13 samples, respectively. IL-2 and IL-5 mRNAs were not found. A significant increase in the expression of IL-1 alpha, TNF-alpha, IL-10, and TGF-beta was observed in late lesions (> or = 4 months) compared with that in early lesions (< or = 2 months). Because of their inhibitory effects on macrophage function, the expression of IL-10 and TGF-beta may play a role in the immunopathogenesis of chronic cutaneous leishmaniasis.

Adhesion molecules in lesions of American cutaneous leishmaniasis

Accessory signals, which include adhesion molecules, MHC-II molecules and cytokines, are necessary to foster the interaction between memory T cells and epidermal cells, that is required to promote cutaneous inflammatory responses. American cutaneous leishmaniasis (ACL) is characterized by a spectrum of immunological manifestations, and is a prototype disease for the study of regulatory mechanisms involved in immune protection against protozoal infection. In the present study, we show that diffuse cutaneous leishmaniasis (DCL) epidermis contains keratinocytes that do not express ICAM-1 and HLA-DR molecules. Langerhans cells (LC) are within normal values or somewhat lower, and a very few cells expressing the HB15 molecule--a new described member of the Ig superfamily--are found in such lesions. Mucocutaneous leishmaniasis (MCL) epithelium shows an increased expression of ICAM-1 and HLA-DR molecules, few HB15+ cells, and an absence of epithelial LC. Localized cutaneous leishmaniasis (LCL) epidermis displays ICAM-1+ keratinocytes organized in patches, a uniform expression of HLA-DR, hyperplasia of LC, and numerous HB15+ cells. In all forms of the disease, infiltrating T cells express more LFA-1 beta than LFA-1 alpha, but LFA-1 beta+ T cells are more abundant in LCL granulomas. In contrast, there are more LFA-1 alpha+ T cells in DCL and MCL than in LCL granulomas. LCL lesions also show the highest numbers of HB15+ cells within the granuloma. These results indicate the importance of adhesion molecules in ACL lesions, and open new possibilities for therapeutic schemes oriented towards the control of cell migration.

Interleukin 12 and the regulation of CD4+ T-cell subset responses during murine Leishmaniasis

Interleukin 12 is unique among cytokines in that it is capable of protecting genetically susceptible mice against progressive infection with Leishmania major. Because of the probable causal relationships between CD4(+) T-cell differentiation, cytokine production and disease outcome, this cytokine may prove useful as a component of cytokine-bosed therapies and Thl-selective vaccines, as discussed here by Frederick Heinzel.

T-cell and cytokine responses in leishmaniasis

Intracellular pathogens, particularly those that inhabit lymphocytes and macrophages, represent unique challenges to the immune system. Leishmania are protozoan parasites that replicate exclusively in macrophages and are thus in an excellent position to influence lymphocyte responses. T cell responses are critical in determining the outcome of infections with Leishmania. In both murine and human infections, strong T helper type 2 responses have been associated with disease, and a decreased or absent T helper type 2 response has been associated with healing.