IFN-γR2 is strongly expressed on endothelial cells of gingival tissues from patients with chronic periodontitis

Abstract Chronic periodontitis (CP) is characterized by gingival inflammation and bone destruction. It has been reported that interferon-gamma (IFN-γ) levels are high in CP patients; however, the IFN-γ receptor (IFN-γR) has not been studied in gingival tissue from these patients. Objective: To evaluate IFN-γ levels and IFN-γR expression in gingival tissue biopsies from chronic periodontitis patients compared with healthy subjects (HS). Material and Methods: Gingival tissues were obtained from all study subjects, CP (n = 18) and healthy subjects (HS) (n = 12). A tissue section of each study subject was embedded in paraffin blocks to determine the expression of IFN-γ R (IFN-γR1 and IFN-γR2) through immunohistochemistry. Another section of the tissue was homogenized and IFN-γ was measured by the ELISA technique. Results: No significant differences were found in the IFN-γR1 expression within the cell layers of the gingival tissue of the study groups. When analyzing the IFN-γR2 expression it was found that IFN-γR2 is strongly expressed in the endothelial cells of CP patients when compared to HS (p<0.05). IFN-γ concentrations in the gingival tissue were significantly higher in CP patients than in HS. No significant correlation between IFN-γ levels and the expression of IFN-γR1 and IFN-γR2 was found. However, a positive correlation between IFN-γ levels and clinical parameters [probing depth (PD) and clinical attachment level (CAL)] was found. Conclusion: The study of IFN-γR expression in gingival tissue samples from patients with CP showed an increase only in the IFN-γR2 chain in endothelial cells when compared to HS.

Infection-stimulated anemia results primarily from interferon gamma-dependent, signal transducer and activator of transcription 1-independent red cell loss / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Although the onset of anemia during infectious disease is commonly correlated with production of inflammatory cytokines, the mechanisms by which cytokines induce anemia are poorly defined. This study focused on the mechanism research.</p><p><b>METHODS</b>Different types of mice were infected perorally with Toxoplasma gondii strain ME49. At the indicated times, samples from each mouse were harvested, processed, and analyzed individually. Blood samples were analyzed using a Coulter Counter and red blood cell (RBC) survival was measured by biotinylation. Levels of tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), and inducible protein 10 (IP-10) mRNA in liver tissue were measured by real-time polymerase chain reaction.</p><p><b>RESULTS</b>T. gondii-infected mice exhibited anemia due to a decrease in both erythropoiesis and survival time of RBC in the circulation (P < 0.02). In addition, infection-stimulated anemia was associated with fecal occult, supporting previous literature that hemorrhage is a consequence of T. gondii infection in mice. Infection-induced anemia was abolished in interferon gamma (IFNγ) and IFNγ receptor deficient mice (P < 0.05) but was still evident in mice lacking TNF-α, iNOS, phagocyte NADPH oxidase or IP-10 (P < 0.02). Neither signal transducer and activator of transcription 1 (STAT1) deficient mice nor 129S6 controls exhibited decreased erythropoiesis, but rather suffered from an anemia resulting solely from increased loss of circulating RBC.</p><p><b>CONCLUSIONS</b>Infection-stimulated decrease in erythropoiesis and losses of RBC have distinct mechanistic bases. These results show that during T. gondii infection, IFNγ is responsible for an anemia that results from both a decrease in erythropoiesis and a STAT1 independent loss of circulating RBC.</p>

Interferon-gamma receptor 1 deficiency in a 19-month-old child: case report and literature review / 中华儿科杂志

<p><b>OBJECTIVE</b>To analyze the clinical manifestation of interferon gamma receptor 1 deficiency (IFN-γR1 deficiency) and to improve the recognition of this disease in children, decrease diagnostic errors and missed diagnosis.</p><p><b>METHOD</b>The information of one case with IFN-γR1 deficiency (past history of illness, clinical manifestation, laboratory examination and treatment) were analyzed.</p><p><b>RESULT</b>The patient was a 19-month-old girl with IFN-γR1 deficiency, 1-2 weeks after she was vaccinated with BCG at the age of 18 months, she manifested with lymph nodes at the same site as vaccination site, and repeated rash. Examination found a mass in the right armpit, the size was 3 cm × 3 cm, protruded on the skin, tenacious in nature, poorly mobile. B-mode ultrasound showed right armpit chest heterogeneous hypoechoic mass; abdominal B-mode ultrasound showed pancreatic lymph nodes around the abdominal aorta and mild swelling; chest X-ray showed right axillary lymph nodes, increased double markings. Initial diagnosis was (1) bronchitis, (2) BCG vaccination reaction, (3) Sepsis? . After admission, the patient was given rifampicin + isoniazid + latamoxef + amoxicillin and clavulanate potassium, and then changed to meropenem and Fusidic acid, but treatment showed no improvement. After adding the treatment with anti-inflammatory treatment, i.e., gamma globulin and methylprednisolone, the fever subsided. Conventional treatment with rifampicin + isoniazid 3 months after discharge from hospital were effective, and the axillary lymph nodes were not palpable. Six months after BCG vaccination bone tuberculosis occurred. CT of left hip and left knee showed bilateral hip joint effusion, left distal femur and left proximal tibia bone destruction. Gene detection showed the presence of homozygous IFNγ-R1 gene mutation of c.114_135del(p.E38fsX54). Her parents are consanguinity, both were carriers. In the literature, 99 cases with IFN-γR1 deficiency were reported, 95% of the cases had disseminated tuberculosis, and in 60 cases the dissemination occurred after BCG vaccination.</p><p><b>CONCLUSION</b>IFN-γR1 is an extremely rare disease in children. If disseminated tuberculosis infection occured, especially after BCG vaccination, or if there were focal/multifocal bone tuberculosis, immune function with conventional detection is considered normal, then IFN-γR1 deficiency should be considered, and early genetic testing for confirming the diagnosis and selecting the appropriate treatment are needed.</p>

Association between interferon gamma receptor 1-56C/T gene polymorphism and tuberculosis susceptibility: a meta-analysis / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Genetic variations in the interferon-gamma (IFN-γ) receptor 1 gene (IFNGR1) may contribute to tuberculosis (TB) risk in different populations. Many studies have investigated the relationship between IFNGR1 56C/T polymorphism and the susceptibility to TB, but have yielded conflicting results. A comprehensive meta-analysis is needed to provide a more accurate estimation of the relationship between them.</p><p><b>METHODS</b>A literature search based on a combination of manual and computer-based methods was conducted on four English databases (PubMed, Science Direct, SpringerLink, and EBSCO) and three Chinese databases (Wanfang, CQVIP, and Chinese National Knowledge Infrastructure databases). Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using either the fixed-effects model or the random-effects model for different genetic models based on the heterogeneity examination.</p><p><b>RESULTS</b>A total of six studies comprising 1 497 confirmed TB cases and 1 802 controls were included in this meta-analysis. Overall, no significant association was observed between IFNGR1 -56C/T polymorphism and TB susceptibility (C vs. T, OR = 0.90, 95% CI 0.69-1.17; CC vs. TT, OR = 0.87, 95% CI 0.65-1.18; TC vs. TT, OR = 1.031, 95% CI 0.872-1.219; CC+TC vs. TT, OR = 0.89, 95% CI 0.64-1.26; CC vs. TC+TT, OR = 0.92, 95% CI 0.66-1.29). In subgroup analysis, a significant association was found in the dominant model (CC+TC vs. TT, OR = 1.24, 95% CI 1.02-1.51) in Africans, but not in Asians or Caucasians.</p><p><b>CONCLUSIONS</b>Our meta-analysis did not provide enough powerful evidence to identify a significant association between IFNGR1 -56C/T polymorphism and TB susceptibility in the overall population. In subgroup analysis, it indicates that IFNGR1 -56C/T is possibly associated with increased TB risk in Africans, but not in Asians or Caucasians. However, larger sample size and better-designed case-control studies are needed to validate these findings.</p>

Partial Interferon-gamma Receptor Deficiency in Patients with Disseminated Tuberculosis / 결핵및호흡기질환

BACKGROUND: Interferon-gamma (IFN-gamma) is essential in the immune response to mycobacterial infections, and a complete or partial deficiency in the IFN-gamma receptor 1 (IFNgammaR1) or the IFN-gamma receptor 2 (IFNgammaR2) have been reported to confer susceptibility to a disseminated infection with nontuberculous mycobacteria. However, similar mutations in the IFN-gamma receptor have not been specifically examined in the patients with clinical tuberculosis. METHODS: This study searched for mutations in the IFN-gamma receptor gene that resulted in a partial IFN-gamma receptor deficiency in six patients with disseminated tuberculosis. The previously identified IFNgammaR1 and IFNgammaR2 coding regions were sequenced after amplification. RESULTS: There was no partial IFNgammaR1 deficiency including a homozygous recessive missense mutation causing an amino-acid substitution in the extracellular domain of the receptor (I87T) and a hotspot for small deletions (818delT, 818del4, 818insA) found in any of the patients. In addition, a partial IFNgammaR2 deficiency of the homozygous missense mutation (R114C) was not found in any of the patients. CONCLUSION: Genetic defects causing a partial IFN-gamma receptor deficiency were not identified in our patients with disseminated tuberculosis.

Experimental reproduction of proliferative enteropathy and the role of IFN-gamma in protective immunity against Lawsonia intracellularis in mice

Proliferative enteropathy was reproduced in IFN-gamma receptor knockout (IFN-gamma R-) mice by experimental infection with Lawsonia intracellularis (L. intracellularis). The cecum and the colon of the infected mice were evidently enlarged 2 weeks post infection. The presence of L. intracellularis was identified in the stool and the cecum of the mice after infection. However, high levels of IFN-gamma were detected in the sera of the infected mice 2 weeks PI. These data indicated that the IFN-gamma produced in the infected mice should have been utilized by it's receptor to elicit protective immune responses against L. intracellularis infections.

Polymorphisms within the interferon-Gamma receptor associated with systemic lupus erythematosus / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the association between polymorphisms within the interferon-Gamma receptor gene(IFN-GammaR) and systemic lupus erythematosus (SLE) in Chinese people.</p><p><b>METHODS</b>The IFN-GammaR genotypes of 94 SLE patients and 80 healthy subjects were examined by the reverse transcription-polymerase chain reaction (RT-PCR)-single-strand conformation polymorphism (SSCP) method, RT-PCR-restriction fragment length polymorphism (RFLP) method and DNA sequencing.</p><p><b>RESULTS</b>There was no statistically significant difference in the IFN-GammaR genotype frequencies between the two groups. The IFN-Gamma R2 Arg64/Arg64 genotype decreased the risk of SLE (OR = 2.481, 95% CI 0.992 - 6.203, P = 0.047). The decreased risk of the development of SLE was detected in the individuals who had the combination of IFN-GammaR2 Arg64/Arg64 genotype and IFN-GammaR1 Val14/Val14 genotype (OR = 2.481, 95% CI 0.992 - 6.203, P = 0.047).</p><p><b>CONCLUSION</b>The IFN-GammaR2 Arg64/Arg64 genotype does not determine susceptibility to SLE in Chinese people, and the combination of IFN-Gamma R2 Arg64/Arg64 genotype and IFN-Gamma R1 Val14/Val14 genotype does not, either.</p>

The construction of attenuated Tiantan recombinant vaccinia virus vector with IFN-gamma receptor gene deletion / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>B8R gene encodes a secreted protein with homology to IFN-gamma receptor, which neutralizes the antiviral and immunological regulation activities of IFN-gamma. To improve the safety of vaccinia virus vector, an attenuated recombinant vaccinia virus with the B8R gene deletion from Tiantan vaccine strain (VTT) was constructed.</p><p><b>METHODS</b>The transfer vectors were generated by joining B8R left flank, B8R right flank, vv promoter, LacZ, multicloning site and pBRSK fragments. The recombinant viruses VTTdeltaB8RLacZ (VTT with B8R deletion and LacZ insertion) were constructed by homologous recombination.</p><p><b>RESULTS</b>The B8R deletion mutants were confirmed by dot blot with B8R gene probe and PCR amplification. The replication ability of VTTdeltaB8RLacZ strain in vitro was similar to that of the VTT. The skin lesions formed by VTTdeltaB8RLacZ (10(6) pfu) were significantly smaller and healed faster than those formed by VTT when injected intradermally to the rabbits,and no visible ulceration occurred. Meanwhile LacZ in VTKgpedeltaB8RLacZ was expressed stably.</p><p><b>CONCLUSIONS</b>The attenuated vector with B8R gene deletion improves the safety of recombinant vaccinia virus vaccine B8R locus may be used as a new site for insertion of foreign genes in vaccinia virus vector.</p>

Expression of IFN-gamma and its receptor alpha in the peripheral blood of patients with chronic hepatitis C / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>It has been known that intra-cellular immunity is important for defense against viral infections and this function lies with interferon gamma (INF-gamma). Here we evaluated the role of IFN-gamma system in the pathogenesis of chronic hepatitis C (CHC).</p><p><b>METHODS</b>The levels of interferon gamma receptor alpha (IFNGR alpha) on the peripheral lymphocyte membrane were assayed with flow cytometry. The plasma concentrations of the cytokines IFN-gamma and IL-10 in CHC patients and normal controls were assayed by enzyme-linked-immunosorbent assay (ELISA). The samples were collected randomly from Xinjiang Autonomous Region, Zhejiang and the northern regions of Jiangsu Province in China.</p><p><b>RESULTS</b>The levels of IFNGR alpha in CHC patients were significantly lower than that of normal controls (NC), especially among patients during the stable stage (P < 0.001), whereas there were no significant differences between CHC in active and stable stages. Among the patients of the three regions, there were no significant differences between patients from Xinjiang and Zhejiang provinces, but both had statistically significant difference compared with the patients from Jiangsu Province (P < 0.001). Plasma IFN-gamma and IL-10 concentrations in CHC patients decreased significantly, IFN-gamma in particular, but there were no significant differences in these levels between various stages of the disease. The IFN-gamma/IL-10 (Th1/Th2) ratio in patients was reversed.</p><p><b>CONCLUSION</b>There may be defects in the IFN-gamma system in chronic HCV infected subjects and a low immune response, which may play an important role in the persistence of HCV infection.</p>

Modulation and implications in pathogenesis of interferon gamma receptor 1 in patients with chronic hepatitis B / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To study the possible differences in the interferon gamma receptor (IFN-gamma R1) response among a variety of clinical types in patients with chronic hepatitis B (CHB) and implications in pathogenesis.</p><p><b>METHODS</b>The serum level of IFN-gamma and the expression level of IFN-gamma R1 in peripheral leucocytes, from 53 CHB patients, were examined by ELISA and flow cytometry respectively, which were compared with the baseline levels of 15 healthy controls and were performed correlation analysis with alanine aminotransferase (ALT), total bilirubin (TBil) in serum and morphological change in hepatic tissues.</p><p><b>RESULTS</b>The results showed that the level of IFN-gamma R1 (28.89% 11.77%) expressed on the membranes of lymphocytes in CHB patients, which correlated with liver inflammation (r=0.621, P<0.01) and serum TBil level (r=0.575, P<0.01), was much higher than that (9.23% 1.30%) of the healthy controls (Z=3.988, P<0.05), and no obvious difference on the membranes of leucocytes. The serum levels of IFN-gamma in patients with cirrhosis and severe hepatitis were higher than those of healthy controls. And the two was no difference from each other, but the standard deviation in each group was relatively large.</p><p><b>CONCLUSION</b>These findings suggest that the IFN-gamma signal transduction pathway is modulated through up-regulating the expression of IFN-gamma R1 on the membranes of lymphocytes, which takes part in the immuno-pathogenesis in CHB patients.</p>

Mutation of LoopAB in HuIFN 1c/86D and enhancement of antiviral activity / 中华实验和临床病毒学杂志

<p><b>BACKGROUND</b>Based on the earlier mapping of the epitope recognized by neutralizing antibody, the authors directly replaced binding domain of IFN in AB-loop for enhancement of biological activity.</p><p><b>METHODS</b>Two unique restriction sites (EcoR? and BsE?) were created into region flanking LoopAB. Casette mutagesis, restriction enzyme digestion, DNA sequencing, antiviral activity assay and antiproliferative activity assay have been used in the project.</p><p><b>RESULTS</b>The mutated residues M31?D,D32?P of LoopAB in parent IFN were produced. The recombinant phagemid pCANTAB5E/3132IFN 1c/86D and expression plasmid PBV322-132IFN 1c/86D were constructed respectively by replacing the corresponding LoopAB with DNA fragment mutated in the residues M31?D,D32?P, which have been confirmed. The recombinant protein has been expressed in E.coli JM103. The crude 3132IFN 1c/86D has been assayed on human WISH cells challenged with VSV and on HeLa cells by colorimetric MTT. 3132IFN 1c/86D showed 8-old antiviral activity compared to that of parent IFN 1c/86D, while IFN?induced growth inhibition of both types had no difference.</p><p><b>CONCLUSIONS</b>The authors concluded that a mutant IFN with enhanced antiviral activity can be obtained via a targeted replacement of receptor binding domain in AB-loop.</p>

Expression and biological activity of two recombinant polypeptides related to subunit 1 of the interferon-alpha receptor

Abnormal production of interferon alpha (IFN-a) has been found in certain autoimmune diseases and can be also observed after prolonged therapy with IFN-a. IFN-a can contribute to the pathogenesis of allograft rejection in bone marrow transplants. Therefore, the development of IFN-a inhibitors as a soluble receptor protein may be valuable for the therapeutic control of these diseases. We have expressed two polypeptides encoding amino acids 93-260 (P1) and 261-410 (P2) of the extracellular domain of subunit 1 of the interferon-a receptor (IFNAR 1-EC) in E. coli. The activities of the recombinant polypeptides and of their respective antibodies were evaluated using antiproliferative and antiviral assays. Expression of P1 and P2 polypeptides was achieved by transformation of cloned plasmid pRSET A into E. coli BL21(DE3)pLysS and by IPTG induction. P1 and P2 were purified by serial sonication steps and by gel filtration chromatography with 8 M urea and refolded by dialysis. Under reducing SDS-PAGE conditions, the molecular weight of P1 and P2 was 22 and 17 kDa, respectively. Polyclonal anti-P1 and anti-P2 antibodies were produced in mice. P1 and P2 and their respective polyclonal antibodies were able to block the antiproliferative activity of 6.25 nM IFN-aB on Daudi cells, but did not block IFN-aB activity at higher concentrations (>6.25 nM). On the other hand, the polypeptides and their respective antibodies did not inhibit the antiviral activity of IFN-aB on Hep 2/c cells challenged with encephalomyocarditis virus.

BCG dissemination in 40 patients and the review of leukocyte mycobacterium deffect in one patient

We have reviewed the medical records of 40 patients with disseminated [Bacille Calmette-Guerin] BCG from 1996 to 1999 in the Immunology Department of the Children Hospital, Medical Center, Tehran University. These patients are divided in to 3 groups: 1. patients who had disseminated [Bacille Calmette-Guerin] BCG after vaccination and their diagnosis was chronic granulomatous disease. 2. Patients who had disseminated [Bacille Calmette-Guerin] BCG and were diagnosed as having cell mediated immunodeficiency. 3. patients whose Nitroblue Tetrazulium and CMI were around normal, but they could not kill intracellular mycobacterium, because of confirmed deficiency of interferon-gamma receptor and IL[12] receptor. Interferon-gamma receptor or CD119 was checked in 6 patients. In one patient interferon-gamma receptor deficiency was confirmed by flowcytometric analysis. In other patients, this marker was around normal, but presumably they had IL[12] receptor deficiency, which we were unable to detect in our laboratory. In some patients this marker should be checked after preparation of more laboratory facilities

Surface redistribution of interferon ç-receptor and its colocatization with the actin cytoskeleton

Background. Specific antibodies for human IFNç-R1 were used to examine its mobilization in Colo 205 cells. Methods. We report here that antibody-IFNç-R1 complex induced capping and actin colocalization. Pretreatment witrh cytochalasin D abolished this capping. To define the role of the IFNç-R1 in the possible interaction with actin, transfected murine fibroblasts cell line with human cDNA IFNç-R1 were used. Results. Only those cells expressing the full receptor and cultured in suspension polarized the receptor and this colocalized with actin filaments. Nevertheless, cells truncated in their intracellular domain displayed no capping and actin remained unaltered either in suspension or in monolayer culture conditions. As mutant bearing an IFNç-R1 with substitutions in positions 270-271 of the intracellular domain redistributed both IFNç-R1 and actin as micropatches instead of capping. Mutation in 256-303 residues resulted in IFNç-R1 microaggregates but actin remained unchanged. Conclusions. These experimental models allowed us to highlight an apparent receptormicrofilament association through the intracellular domain of IFNç-R1, and to specifically locate it within the intracellular region 256-303 that has been identified as relevant for ligand-receptor internalization and biological function

Atividade parasiticida e/ou parasitostática de fibroblastos e macrofagos humanos ativados por rIFN-y e/ou rTNF-x / Parasiticides activity and/or parasitostática of fibroblasts and macrophages activated by human rIFN-y and / or rTNF-x

Estudamos o papel da degradação do triptofano pela indoleamina 2,3-dioxigenase (INDO) no controle da replicação do T. cruzzi ou T. gondii em fibroblastos e macrófagos humanos estimulados com rIFN-gama e/ou rTNF-alfa. O T. gondii foi utlizado como controle, por ser sensível à degradação do triptofano induzida pelo rIFN-gama. A estimulação de fibroblastos humanos com rIFN-gama e o rTNF-alfa inibiu consideravelmente o desenvolvimento do T. gondii, mas não influenciou o desenvolvimento do T. cruzi. O desenvolvimento do T. gondii foi triptofano dependente, enquanto que o do T. cruzi foi triptofano independente. Ao contrário dos fibroblastos parentais, os fibroblastos defectivos na via de transdução de sinal do IFN-gama (JAKI, JAK2 e STAT1alfa) não modularam o desenvolvimento intracelular de T. gondii e nem expressaram mRNA da INDO quando estimulados pelo rIFN-gama. Houve uma pequena indução de mRNA da INDO em fibroblastos parentais e mutantes (JAK2) estimulados com rTNF-alfa, que provavelmente foi estimulado através da indução da síntese de IFN-es em fibroblastos humanos. O rIFN-gama e/ou rTNF-alfa induziram expressiva atividade tripanosomicida em macrófagos humanos. A estimulação de macrófagos humanos com rIFN-gama ou rIFN-gama + rTNF-alfa, produziu uma considerável expressão do mRNA da INDO, e pouca expressão foi detectada quando as células foram estimuladas apenas com rTNF-alfa. A adição de triptofano, ou do inibidor da INDO, norharmane, à cultura de macrófagos humanos ativados com rIFN-gama e/ou rTNF-alfa, não reverteu a inibição do crescimento do parasita, mostrando que a degradação do triptofano não é um mecanismo responsável pelo efeito tripanosomicida de macrófagos humanos ativados com rIFN-gama e/ou rTNF-alfa. Os catabólitos do triptofano (ácido quinolínico, ácido quinurênico e L-quinurenina) inibiram parcialmente o desenvolvimento do T. cruzi em macrófagos humanos. A amplificação por PCR do DNA T. cLsintese de Escherichia coli ou Neurospora crassa e Saccharomyces cerevisae e a hibridização cruzada via dot blot utilizando como sondas os produtos de PCR, sugerem a possibilidade da existência da enzima triptofano sintetase em T. cruzi, o que explicaria a insensibilidade do parasita à depleção do triptofano. Alternativamente reconhecemos que mais estudos devam ser feitos para a comprovação da existência da enzima em T. cruzi.

Atividade parasiticida e/ou parasitostática de fibroblastos e macrofagos humanos ativados por rIFN-y e/ou rTNF-x

Estudamos o papel da degradação do triptofano pela indoleamina 2,3-dioxigenase (INDO) no controle da replicação do T. cruzzi ou T. gondii em fibroblastos e macrófagos humanos estimulados com rIFN-gama e/ou rTNF-alfa. O T. gondii foi utlizado como controle, por ser sensível à degradação do triptofano induzida pelo rIFN-gama. A estimulação de fibroblastos humanos com rIFN-gama e o rTNF-alfa inibiu consideravelmente o desenvolvimento do T. gondii, mas não influenciou o desenvolvimento do T. cruzi. O desenvolvimento do T. gondii foi triptofano dependente, enquanto que o do T. cruzi foi triptofano independente. Ao contrário dos fibroblastos parentais, os fibroblastos defectivos na via de transdução de sinal do IFN-gama (JAKI, JAK2 e STAT1alfa)não modularam o desenvolvimento intracelular de T. gondii e nem expressaram mRNA da INDO quando estimulados pelo rIFN-gama. Houve uma pequena indução de mRNA da INDO em fibroblastos parentais e mutantes (JAK2) estimulados com rTNF-alfa, que provavelmente foi estimulado através da indução da síntese de IFN-es em fibroblastos humanos. O rIFN-gama e/ou rTNF-alfa induziram expressiva atividade tripanosomicida em macrófagos humanos.

A estimulação de macrófagos humanos com rIFN-gama ou rIFN-gama + rTNF-alfa, produziu uma considerável expressão do mRNA da INDO, e pouca expressão foi detectada quando as células foram estimuladas apenas com rTNF-alfa. A adição de triptofano, ou do inibidor da INDO, norharmane, à cultura de macrófagos humanos ativados com rIFN-gama e/ou rTNF-alfa, não reverteu a inibição do crescimento do parasita , mostrando que a degradação do triptofano não é um mecanismo responsável pelo efeito tripanosomicida de macrófagos humanos ativados com rIFN-gama e/ou rTNF-alfa. Os catabólitos do triptofano (ácido quinolínico, ácido quinurênico e L-quinurenina)inibiram parcialmente o desenvolvimento do T. cruzi em macrófagos humanos. A amplificação por PCR do DNA T. cLsintese de Escherichia coli ou Neurospora crassa e Saccharomyces cerevisae e a hibridização cruzada via dot blot utilizando como sondas os produtos de PCR, sugerem a possibilidade da existência da enzima triptofano sintetase em T. cruzi, o que explicaria a insensibilidade do parasita à depleção do triptofano. Alternativamente reconhecemos que mais estudos devam ser feitos para a comprovação da existência da enzima em T. cruzi