Increased Natural Killer (NK)-cell cytotoxicity and Trypanosoma cruzi-specific memory B cells in subjects with discordant serology for Chagas disease.

The presence of memory T cell specific for Trypanosoma cruzi in subjects with discordant serology for Chagas disease supports a cleared infection in these subjects. Using high-dimensional flow cytometry, ELISPOT assays and quantitative PCR, antibody-secreting cells and memory B cells specific for T. cruzi, total B-cell phenotypes, innate immune responses and parasite DNA were evaluated in serodiscordant, seropositive and seronegative subjects for T. cruzi infection. T. cruzi-specific memory B cells but no antibody-secreting cells specific for T. cruzi, increased proportion of nonclassical monocytes and increased levels of polyfunctional NK cells were found in serodiscordant compared with seropositive subjects. None of the serodiscordant subjects evaluated showed detectable parasite DNA, most of them did not show cardiac abnormalities and a group of them had had confirmed positive serology for Chagas disease. The unique immune profiles in serodiscordant subjects support that T. cruzi infection was cleared or profoundly controlled in these subjects.

Perfil de parámetros hematológicos en el HIV pediátrico y los cambios asociados al tratamiento antirretroviral / Hematological parameters profile in pediatric HIV and changes associated with antiretroviral treatment / Perfil de parâmetros hematológicos no HIV pediátrico e as alterações associadas ao tratamento anti-retroviral

Resumen Las alteraciones hematológicas son comunes durante la infección por el virus de la inmunodeficiencia humana (HIV). El objetivo de este trabajo fue describir los perfiles hematológicos e inmunológicos de niños infectados, antes y después de 36 meses de implementado el tratamiento antirretroviral (TARV). Se revisaron historias clínicas de niños expuestos, atendidos en este hospital en el período 2008-2018, con edades entre 6 meses y 14 años. Fueron empleados un contador hematológico (ADVIA 2120), un citómetro de flujo (FACScalibur BD) y una PCR en tiempo real Nuclisens EasyQ (bioMérieux). En 486 historias clínicas se encontraron 58 pacientes sin TARV, 30 por diagnóstico reciente y 28 por adherencia incorrecta o abandono de tratamiento. En ambos grupos se observó disminución porcentual de hemoglobina (Hb) (53% y 43%), volumen corpuscular medio (VCM) (43% y 7%) y LTCD4+ (37% y 57%), respectivamente, sin alteraciones significativas en otros parámetros hematológicos. Veintidós niños con correcta adherencia al TARV incrementaron significativamente los niveles de LTCD4+ (t0:18,8±9%, t1:32,7±6%), Hb (t0:10,9±1,6 g/dL, t1:12,6±1,1g/dL) y VCM (t0:78,7±4,5 fL, t1:101,9±5,6 fL), con disminución simultánea de la carga viral (CV) (t0:4,4±0,75 log t1:<1,70 log) después del seguimiento. La disminución de Hb observada aproximadamente en el 50% de los pacientes sin TARV estaría asociada a la acción viral y al tiempo de evolución de la infección. El incremento en los niveles, asociados a macrocitosis, se relacionaría con el aumento de LTCD4+ y disminución de la CV.

Abstract Hematologic abnormalities are common during human immunodeficiency virus (HIV) infection. Our aim was to describe hematological and immunological profiles present in antiretroviral treatment (ART)-naïve infected children and the changes observed after 36 months of ART initiation. Medical records of exposed children attended at this hospital in the 2008-2018 period were reviewed. Children between 6 months and 14 years were included. An automated blood analyser ADVIA 2120, a FACScalibur BD flow cytometer, and a Nuclisens EasyQ bioMérieux real-time PCR were used to determine different parameters. In 486 medical records evaluated, 58 patients ART-naïve were found, 30 due to recent diagnosis and 28 for incorrect adherence or abandoned treatment. In both groups, a percentage decrease in hemoglobin (Hb) (53% and 43%), mean corpuscular volume (MCV) (43% and 7%) and LTCD4+ (37% and 57%) levels respectively, was observed, without significant alterations in other hematological parameters. Twenty-two children with ART correct adherence increased significantly CD4+T cells (t0:18.8±9%, t1:32.7±6%), Hb (t0:10.9±1.6 g/dL, t1:12.6±1.1 g/dL) and MCV (t0:78.7±4.5 fL, t1:101.9±5.6 fL) levels, with simultaneous decrease of viral load (VL), (t0:4.4±0.75 log, t1:<1.70 log), after 36 months of follow-up. The reduction in Hb levels observed in 50% approximately of patients without ART would be associated with viral action and time of evolution of the infection. The increase in Hb levels and an associated macrocytosis would be related to the CD4+ T cells increase and VL decrease.

Resumo Alterações hematológicas são comuns durante a infecção pelo vírus da imunodeficiência humana (HIV). Nosso objetivo foi descrever os perfis hematológicos e imunológicos em crianças infectadas, antes e após 36 meses de implementar o tratamento antirretroviral (TARV). Foram revisados os prontuários das crianças expostas atendidas neste hospital no período 2008-2018, com idade entre 6 meses e 14 anos. Um contador hematológico (ADVIA 2120), um citômetro de fluxo (FACScalibur BD) e um PCR em tempo real Nuclisens EasyQ (bioMérieux), foram usados. Em 486 prontuários foram encontrados 58 pacientes livres de TARV, 30 por diagnóstico recente e 28 por adesão incorreta ou abandono do tratamento. Em ambos os grupos, observou-se diminuição percentual de hemoglobina (Hb) (53% e 43%), volume corpuscular médio (VCM) (43% e 7%) e LTCD4+ (37% e 57%), respectivamente, sem alterações significativas nos demais parâmetros hematológicos. Vinte e duas crianças com adesão correta ao TARV aumentaram significativamente os níveis de LTCD4+ (t0:18,8±9%, t1:32,7±6%), Hb (t0:10,9±1,6 g/dL, t1:12,6±1,1 g/dL) e VCM (t0:78,7±4,5 fL, t1:101,9±5,6 fL), com diminuição simultânea da carga viral (CV) (t0:4,4±0,75 log, t1:<1,70 log), depois do seguimento. A diminuição dos níveis de Hb observada em aproximadamente 50% dos pacientes sem TARV estaria associada à ação viral e ao tempo de evolução da infecção. O aumento nos níveis, associados a macrocitose, estaria relacionado com o aumento de LTCD4+ e diminuição da CV.

Trypanosoma cruzi Secreted Cyclophilin TcCyP19 as an Early Marker for Trypanocidal Treatment Efficiency.

Cyclophilins (CyPs) are a family of enzymes involved in protein folding. Trypanosoma cruzi, the causative agent of Chagas disease, has a 19-kDa cyclophilin, TcCyP19, that was found to be secreted in parasite stages of the CL Brener clone and recognized by sera from T. cruzi-infected mice and patients. The levels of specific antibodies against TcCyP19 in T. cruzi-infected mice and subjects before and after drug treatment were measured by an in-house enzyme linked immunosorbent assay (ELISA). Mice in the acute and chronic phase of infection, with successful trypanocidal treatments, showed significantly lower anti-TcCyP19 antibody levels than untreated mice. In children and adults chronically infected with T. cruzi, a significant decrease in the anti-TcCyP19 titers was observed after 12 months of etiological treatment. This decrease was maintained in adult chronic patients followed-up 30-38 months post-treatment. These results encourage further studies on TcCyP19 as an early biomarker of trypanocidal treatment efficiency.

Mixed T Helper1/T Helper2/T Cytotoxic Profile in Subjects with Chronic Chagas Disease with Hypersensitivity Reactions to Benznidazole.

Dermatitis is the most common adverse event during treatment with benznidazole in chronic Chagas disease and is probably mediated by T cells. A set of molecules representative of the different type IV hypersensitivity reactions was evaluated in the circulation and skin biopsies of Trypanosoma cruzi-infected subjects presenting dermatitis during benznidazole administration. Through cytometric bead assays and enzyme-linked immunosorbent assay capture techniques, the serum levels of cytokines, chemokines, proapoptotic molecules, and mediators of the activation and migration of eosinophils and T cells were measured in subjects infected with Trypanosoma cruzi who exhibited skin adverse events (n = 22) and compared with those without adverse events (n = 37) during benznidazole therapy. Serum levels of interleukin- 5 (IL-5), soluble Fas cell surface death receptor ligand (FAS-L), and interferon γ-induced protein (IP-10) significantly increased at 7 to 30 days posttreatment with benznidazole and decreased thereafter in subjects with dermatitis but not in those without dermatitis. Circulating eotaxin levels were lower in subjects with dermatitis than in those without. Two patterns emerged in the skin biopsies: a T helper 1/T cytotoxic profile and a T helper 2/T cytotoxic profile with the presence of CD4+ and CD8+ T cells. Increased low-density lipoprotein (LDL), glutamic-oxaloacetic transaminase (GOT), uremia, and T cell activation emerged as risk factors for the development of dermatitis during benznidazole administration. These results support a delayed-type hypersensitivity reaction to benznidazole, involving CD4+ and CD8+ T cells and eosinophils, and a mixed cytokine profile. This study provides new insights for better management of adverse drug reactions to benznidazole. IMPORTANCE This study identified the risk factors for the development of adverse reactions to benznidazole and identified a set molecule to monitor the appearance of these reactions. This knowledge might improve the safety of benznidazole administration.

Role of the Complement System in the Modulation of T-Cell Responses in Chronic Chagas Disease.

Chagas disease, caused by the intracellular pathogen Trypanosoma cruzi, is the parasitic disease with the greatest impact in Latin America and the most common cause of infectious myocarditis in the world. The immune system plays a central role in the control of T. cruzi infection but at the same time needs to be controlled to prevent the development of pathology in the host. It has been shown that persistent infection with T. cruzi induces exhaustion of parasite-specific T cell responses in subjects with chronic Chagas disease. The continuous inflammatory reaction due to parasite persistence in the heart also leads to necrosis and fibrosis. The complement system is a key element of the innate immune system, but recent findings have also shown that the interaction between its components and immune cell receptors might modulate several functions of the adaptive immune system. Moreover, the findings that most of immune cells can produce complement proteins and express their receptors have led to the notion that the complement system also has non canonical functions in the T cell. During human infection by T. cruzi, complement activation might play a dual role in the acute and chronic phases of Chagas disease; it is initially crucial in controlling parasitemia and might later contributes to the development of symptomatic forms of Chagas disease due to its role in T-cell regulation. Herein, we will discuss the putative role of effector complement molecules on T-cell immune exhaustion during chronic human T. cruzi infection.

Immune exhaustion in chronic Chagas disease: Pro-inflammatory and immunomodulatory action of IL-27 in vitro.

In chronic Chagas disease, Trypanosoma cruzi-specific T-cell function decreases over time, and alterations in the homeostatic IL-7/IL-7R axis are evident, consistent with a process of immune exhaustion. IL-27 is an important immunoregulatory cytokine that shares T-cell signaling with IL-7 and other cytokines of the IL-12 family and might be involved in the transcriptional regulation of T-cell function. Here, we evaluated the expression and function of IL-27R in antigen-experienced T cells from subjects with chronic Chagas disease and assessed whether in vitro treatment with IL-27 and IL-7 might improve T. cruzi-specific polyfunctional T-cell responses. In vitro exposure of PBMCs to T. cruzi induced a downregulation of IL-27R in CD4+ T cells and an upregulation in CD8+ T cells in subjects without heart disease, while IL-27R expression remained unaltered in subjects with more severe clinical stages. The modulation of IL-27R was associated with functional signaling through STAT3 and STAT5 and induction of the downstream genes TBX21, EOMES and CXCL9 in response to IL-27. In vitro treatment of PBMCs with IL-27 and IL-7 improved monofunctional and polyfunctional Th1 responses, accompanied by the induction of IL-10 and Bcl-2 expression in subjects without heart disease but did not improve those in subjects with cardiomyopathy. Our findings support the process of desensitization of the IL-27/IL-27R pathway along with disease severity and that the pro-inflammatory and immunomodulatory mechanisms of IL-27 might be interconnected.

Reduced Trypanosoma cruzi-specific humoral response and enhanced T cell immunity after treatment interruption with benznidazole in chronic Chagas disease.

BACKGROUND: Interruption of benznidazole therapy due to the appearance of adverse effects, which is presumed to lead to treatment failure, is a major drawback in the treatment of chronic Chagas disease. METHODS: Trypanosoma cruzi-specific humoral and T cell responses, T cell phenotype and parasite load were measured to compare the outcome in 33 subjects with chronic Chagas disease treated with an incomplete benznidazole regimen and 58 subjects treated with the complete regimen, during a median follow-up period of 48 months. RESULTS: Both treatment regimens induced a reduction in the T. cruzi-specific antibody levels and similar rates of treatment failure when evaluated using quantitative PCR. Regardless of the regimen, polyfunctional CD4+ T cells increased in the subjects, with successful treatment outcome defined as a decrease of T. cruzi-specific antibodies. Regardless of the serological outcome, naive and central memory T cells increased after both regimens. A decrease in CD4+ HLA-DR+ T cells was associated with successful treatment in both regimens. The cytokine profiles of subjects with successful treatment showed fewer inflammatory mediators than those of the untreated T. cruzi-infected subjects. High levels of T cells expressing IL-7 receptor and low levels of CD8+ T cells expressing the programmed cell death protein 1 at baseline were associated with successful treatment following benznidazole interruption. CONCLUSIONS: These findings challenge the notion that treatment failure is the sole potential outcome of an incomplete benznidazole regimen and support the need for further assessment of the treatment protocols for chronic Chagas disease.

Circulating Cytokine and Chemokine Profiles of Trypanosoma cruzi-Infected Women During Pregnancy and Its Association With Congenital Transmission.

BACKGROUND: Trypanosoma cruzi, the causative agent of Chagas disease, can be transmitted to the offspring of infected women, which constitutes an epidemiologically significant parasite transmission route in nonendemic areas. It is relevant to evaluate differentially expressed factors in T. cruzi-infected pregnant women as potential markers of Chagas congenital transmission. METHODS: Circulating levels of 12 cytokines and chemokines were measured by enzyme-linked immunosorbent assay or cytometric bead array in T. cruzi-infected and uninfected pregnant women in their second trimester of pregnancy and control groups of T. cruzi-infected and uninfected nonpregnant women. RESULTS: Trypanosoma cruzi-infected women showed a proinflammatory Th1-biased profile, with increased levels of tumor necrosis factor (TNF)-α, interleukin (IL)-12p70, IL-15, and monokine induced by interferon-gamma (MIG). Uninfected pregnant women presented a biased response towards Th2/Th17/Treg profiles, with increased plasma levels of IL-5, IL-6, IL-1ß, IL-17A, and IL-10. Finally, we identified that high parasitemia together with low levels of TNF-α, IL-15, and IL-17, low TNF-α/IL-10 ratio, and high IL-12p70 levels are factors associated with an increased probability of Chagas congenital transmission. CONCLUSIONS: Trypanosoma cruzi-infected pregnant women who did not transmit the infection to their babies exhibited a distinct proinflammatory cytokine profile that might serve as a potential predictive marker of congenital transmission.

New Scheme of Intermittent Benznidazole Administration in Patients Chronically Infected with Trypanosoma cruzi: Clinical, Parasitological, and Serological Assessment after Three Years of Follow-Up.

In a pilot study, we showed that the intermittent administration of benznidazole in chronic Chagas disease patients resulted in a low rate of treatment suspension and therapeutic failure, as assessed by quantitative PCR (qPCR) at the end of treatment. Here, a 3-year posttreatment follow-up study of the same cohort of patients is presented. The treatment scheme consisted of 12 doses of benznidazole at 5 mg/kg of body weight/day in two daily doses every 5 days. Parasite load, Trypanosoma cruzi-specific antibodies, and serum chemokine levels were measured prior to treatment and after a median follow-up of 36 months posttreatment by DNA minicircle kinetoplastid and nuclear DNA satellite sequence qPCR methods, conventional serological techniques, a Luminex-based assay with recombinant T. cruzi proteins, and a cytometric bead array. At the end of follow-up, 14 of 17 (82%) patients had negative qPCR findings, whereas three of 17 (18%) had detectable nonquantifiable findings by at least one of the qPCR techniques. A decline in parasite-specific antibodies at 12 months posttreatment was confirmed by conventional serological tests and the Luminex assays. Monocyte chemoattractant protein 1 levels increased after treatment, whereas monokine induced by gamma interferon levels decreased. New posttreatment electrocardiographic abnormalities were observed in only one patient who had cardiomyopathy prior to treatment. Together, these data strengthen our previous findings by showing that the intermittent administration of benznidazole results in a low rate of treatment suspension, with treatment efficacy comparable to that of a daily dose of 5 mg/kg for 60 days.

B-cell profile, B-cell activating factor concentration and IgG levels in human cutaneous and mucosal leishmaniasis.

AIMS: The aim of this study was to evaluate characteristics of B cells in human tegumentary leismaniasis (TL) analysing cutaneous leishmaniasis (CL), most prevalent form and mucosal leishmaniasis (ML), aggressive form characterized by the destruction of the oral-nasal-pharyngeal cavities. METHODS AND RESULTS: By flow cytometry analysis, we found decreased percentages of non-class-switched memory B cells in TL with the degree of the loss related to clinical severity. Using commercial ELISA, we reported high levels of B-cell activating factor (BAFF) and IgG preferentially in aggressive CL and markedly in ML together with decreased BAFF receptors in the latter. We also found lower levels of BAFF after clinical recovery suggesting a relation between BAFF and disease activity. Mucosal leishmaniasis history of therapeutic failure presented high levels of BAFF accompanied by detectable concentrations of IFN-γ and IL-6 (assayed by commercial ELISA and cytometric bead arrays respectively), cytokines involved in exaggerated inflammatory responses and tissue damage in TL. CONCLUSION: We demonstrate B-cell disturbances in TL with the degree of the alterations related to clinical severity. We suggest a relation between excess of BAFF and disease activity and point towards a possible implication of BAFF in the inflammatory phenomenon of ML.

Restoration of recent thymic emigrant CD4+ T cells is associated with sustained adherence to antiretroviral treatment in HIV-infected children.

To evaluate the levels of recent thymic emigrant (RTE) CD4+ T cells in HIV-infected children and to explore the associations among their frequency, antiretroviral treatment (ART) adherence, and CD4+ T cell restoration. The group evaluated comprised 85 HIV-infected patients classified as subjects with moderate or severe immunosuppression or as those with no evidence of immunosuppression. To evaluate the association between the frequency of RTE CD4+ T cells and ART adherence, 23 of the 85 patients were evaluated at two different time points during a one-year follow-up period. Children with severe immunosuppression had lower frequencies of RTE CD4+ T cells compared with children without evidence of immunosuppression (P < .001). The frequency of RTE CD4+ T cells in children with a high rate of adherence was significantly higher (P < .05) than that observed among those with suboptimal adherence. The latter group presented with infectious intercurrences on admission that decreased after initiation of treatment along with improved CD4+ and RTE naïve CD4+ T cells counts. The adequate ART adherence is essential for immune reconstitution, which might be reflected by the levels of RTE CD4+ T cells.

Trypanosoma cruzi Infection at the Maternal-Fetal Interface: Implications of Parasite Load in the Congenital Transmission and Challenges in the Diagnosis of Infected Newborns.

Trypanosoma cruzi is the protozoan unicellular parasite that causes Chagas disease. It can be transmitted from infected mothers to their babies via the connatal route, thus being able to perpetuate even in the absence of Triatomine insect vectors. Chagas disease was originally endemic in Central and South America, but migration of infected women of childbearing age has spread the T. cruzi congenital infection to non-endemic areas like North America, Europe, Japan, and Australia. Currently, 7 million people are affected by this infection worldwide. This review focuses on the relevance of the T. cruzi parasite levels in different aspects of the congenital T. cruzi infection such as the mother-to-child transmission rate, the maternal and fetal immune response, and its impact on the diagnosis of infected newborns. Improvements in detection of this parasite, with tools that can be easily adapted to be used in remote rural areas, will make the early diagnosis of infected children possible, allowing a prompt trypanocidal treatment and avoiding the current loss of opportunities for the diagnosis of 100% of T. cruzi congenitally infected infants.

Impaired frequencies and function of platelets and tissue remodeling in chronic Chagas disease.

Chronic inflammation, as a consequence of the persistent infection with Trypanosoma cruzi, leads to continuous activation of the immune system in patients with chronic Chagas disease. We have previously shown that increased sera levels of soluble P-selectin are associated with the severity of the cardiomyopathy distinctive of chronic Chagas disease. In this study, we explored the expression of biomarkers of platelet and endothelial activation, tissue remodeling, and mediators of the coagulation cascade in patients at different clinical stages of chronic Chagas heart disease. The frequencies of activated platelets, measured by the expression of CD41a and CD62P were decreased in patients with chronic Chagas disease compared with those in uninfected subjects, with an inverse association with disease severity. Platelet activation in response to adenosine diphosphate was also decreased in T. cruzi-infected subjects. A major proportion of T. cruzi infected subjects showed increased serum levels of fibrinogen. Patients with severe cardiac dysfunction showed increased levels of endothelin-1 and normal values of procollagen I. In conclusion, chronic infection with T. cruzi induced hemostatic alterations, even in those patients who do not yet present cardiac symptoms.

Trypanosoma cruzi-Specific T-Cell Responses to Monitor Treatment Efficacy in Chronic Chagas Disease.

Chagas disease is the highest impact parasitic disease in Latin America. In recent years, the use of immune-related biomarkers to predict diagnostic and treatment efficacy or to monitor diseases has been considered a promising tool. Our group has worked for the past 20 years on the characterization of different immunological aspects of the T-cell responses to T. cruzi antigens. We have shown that monitoring of appropriate immunological responses can provide earlier and robust measures of treatment.The Enzyme-Linked ImmunoSPOT (ELISPOT) assays are powerful tools to evaluate antigen-specific immune responses at the single-cell level. Herein, we describe uses of the ELISPOT assay to determine the T. cruzi-specific T-cell populations in PBMCs from chronic chagasic subjects.

Correction: Trypanosoma cruzi-specific IFN-γ-producing cells in chronic Chagas disease associate with a functional IL-7/IL-7R axis.

[This corrects the article DOI: 10.1371/journal.pntd.0006998.].

Trypanosoma cruzi-specific IFN-γ-producing cells in chronic Chagas disease associate with a functional IL-7/IL-7R axis.

BACKGROUND: The severity of cardiac disease in chronic Chagas disease patients is associated with different features of T-cell exhaustion. Here, we assessed whether the ability of T cells to secrete IFN-γ in response to T. cruzi was linked to disruption in immune homeostasis and inflammation in patients with chronic Chagas disease. METHODOLOGY/PRINCIPAL FINDINGS: PBMCs from chronic Chagas disease patients and uninfected controls were examined for frequencies of T. cruzi-responsive IFN-γ-producing cells by ELISPOT and cellular expression and function of IL-7R using flow cytometry. Serum levels of IL-7, IL-21, IL-27, soluble IL-7R, and inflammatory cytokines were also evaluated by ELISA or CBA techniques. Patients possessing T. cruzi-specific IFN-γ-producing cells (i.e. IFN-γ producers) had higher levels of memory T cells capable of modulating the alpha chain of IL-7R and an efficient response to IL-7 compared to that in patients lacking (i.e. IFN-γ nonproducers) parasite-specific T-cell responses. IFN-γ producers also showed low levels of soluble IL-7R, high basal expression of Bcl-2 in T cells and low basal frequencies of activated CD25+ T cells. Modulation of IL-7R was inversely associated with serum IL-6 levels and positively associated with serum IL-8 levels. Circulating IL-21 and IL-27 levels were not associated with the frequency of IFN-γ producing cells but were reduced in less severe clinical forms of the disease. In vitro stimulation of PBMCs with IL-7 or IL-27 enhanced IFN-γ production in IFN-γ producers but not in IFN-γ nonproducers. CONCLUSIONS/SIGNIFICANCE: Alterations of the IL-7/IL-7R axis and in the levels of inflammatory cytokines were linked to impaired T. cruzi-specific IFN-γ production. These alterations might be responsible of the process of immune exhaustion observed in chronic Chagas disease.

Distinct Treatment Outcomes of Antiparasitic Therapy in Trypanosoma cruzi-Infected Children Is Associated With Early Changes in Cytokines, Chemokines, and T-Cell Phenotypes.

Background: In contrast to adults, Trypanosoma cruzi-infected children have more broadly functional Trypanosoma cruzi-specific T cells, and the total T-cell compartment exhibits fewer signs of immune exhaustion. However, not much is known about the link between immunocompetence and the treatment efficacy for human Chagas disease. Methods: Using cytokine enzyme-linked immunosorbent spot (ELISPOT) polychromatic flow cytometry, cytometric bead assay, multiplex serological assays and quantitative PCR, we evaluated T. cruzi-specific T-cell and antibody immune responses, T-cell phenotypes and parasitemia in children in the early chronic phase of Chagas disease undergoing anti-Trypanosoma cruzi treatment. Results: Treatment with benznidazole or nifurtimox induced a decline in T. cruzi-specific IFN-γ- and IL-2-producing cells and proinflammatory cytokines and chemokines. T-cell responses became detectable after therapy in children bearing T-cell responses under background levels prior to treatment. The total frequencies of effector, activated and antigen-experienced T cells also decreased following anti-T. cruzi therapy, along with an increase in T cells expressing the receptor of the homeostatic cytokine IL-7. Posttreatment changes in several of these markers distinguished children with a declining serologic response suggestive of successful treatment from those with sustained serological responses in a 5-year follow-up study. A multivariate analysis demonstrated that lower frequency of CD4+CD45RA-CCR7-CD62L- T cells prior to drug therapy was an independent indicator of successful treatment. Conclusions: These findings further validate the usefulness of alternative metrics to monitor treatment outcomes. Distinct qualitative and quantitative characteristics of T cells prior to drug therapy may be linked to treatment efficacy.