RESUMO
BACKGROUND: This prospective study characterizes the structural and metabolic cerebral correlates of cognitive impairments found in a preclinical setting that considers the lifestyle of young European men exposed to human immunodeficiency virus (HIV), including recreational drugs. METHODS: Simultaneous structural brain magnetic resonance imaging (MRI) and positron emission tomography using [18F]-fluorodeoxyglucose (FDG-PET) were acquired on a hybrid PET-MRI system in 23 asymptomatic young men having sex with men with HIV (HIVMSM; mean age, 33.6 years [range, 23-60 years]; normal CD4+ cell count, undetectable viral load). Neuroimaging data were compared with that of 26 young seronegative men under HIV preexposure prophylaxis (PrEPMSM), highly well matched for age and lifestyle, and to 23 matched young seronegative men (controls). A comprehensive neuropsychological assessment was also administered to the HIVMSM and PrEPMSM participants. RESULTS: HIVMSM had lower performances in executive, attentional, and working memory functions compared to PrEPMSM. No structural or metabolic differences were found between those 2 groups. Compared to controls, HIVMSM and PrEPMSM exhibited a common hypometabolism in the prefrontal cortex that correlated with the level of recreational drug use. No structural brain abnormality was found. CONCLUSIONS: Abnormalities of brain metabolism in our population of young HIVMSM mainly relate to recreational drug use rather than HIV per se. A complex interplay between recreational drugs and HIV might nevertheless be involved in the cognitive impairments observed in this population.
Assuntos
Disfunção Cognitiva , Infecções por HIV , Drogas Ilícitas , Masculino , Humanos , Adulto , HIV , Drogas Ilícitas/efeitos adversos , Drogas Ilícitas/metabolismo , Estudos Prospectivos , Cognição , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Disfunção Cognitiva/patologia , Fluordesoxiglucose F18/metabolismo , Imageamento por Ressonância Magnética , Tomografia por Emissão de Pósitrons , Infecções por HIV/patologia , Testes NeuropsicológicosRESUMO
Neisseria gonorrhoeae and Chlamydia trachomatis screening was performed in a cohort of 100 men who have sex with men. A nucleic acid amplification test on a pooled sample of first-pass urine, pharyngeal, and anorectal specimens was compared with results on nonpooled samples. Despite an excellent agreement (Cohen κ, 0.932), pooling specimens reduced test sensitivity to 89.5%.
Assuntos
Infecções por Chlamydia/diagnóstico , Gonorreia/diagnóstico , Doenças Faríngeas/diagnóstico , Doenças Retais/diagnóstico , Minorias Sexuais e de Gênero/estatística & dados numéricos , Adolescente , Adulto , Infecções por Chlamydia/microbiologia , Chlamydia trachomatis/genética , Chlamydia trachomatis/isolamento & purificação , Confiabilidade dos Dados , Gonorreia/microbiologia , Homossexualidade Masculina , Humanos , Masculino , Programas de Rastreamento , Pessoa de Meia-Idade , Neisseria gonorrhoeae/genética , Neisseria gonorrhoeae/isolamento & purificação , Técnicas de Amplificação de Ácido Nucleico , Doenças Faríngeas/microbiologia , Faringe/microbiologia , Doenças Retais/microbiologia , Sensibilidade e Especificidade , Adulto JovemRESUMO
BACKGROUND: The screening and treatment of latent tuberculosis (TB) infection reduces the risk of progression to active disease and is currently recommended for HIV-infected patients. The aim of this study is to evaluate, in a low TB incidence setting, the potential contribution of an interferon-gamma release assay in response to the mycobacterial latency antigen Heparin-Binding Haemagglutinin (HBHA-IGRA), to the detection of Mycobacterium tuberculosis infection in HIV-infected patients. METHODS: Treatment-naïve HIV-infected adults were recruited from 4 Brussels-based hospitals. Subjects underwent screening for latent TB using the HBHA-IGRA in parallel to a classical method consisting of medical history, chest X-ray, tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube (QFT-GIT). Prospective clinical and biological follow-up ensued, with repeated testing with HBHA-IGRA. A group of HIV-infected patients with clinical suspicion of active TB was also recruited and tested with the HBHA-IGRA. Multiplex analysis was performed on the culture supernatants of this in-house assay to identify test read-outs alternative to interferon-gamma that could increase the sensitivity of the test. RESULTS: Among 48 candidates enrolled for screening, 9 were identified with latent TB by TST and/or QFT-GIT results. Four of these 9 patients and an additional 3 screened positive with the HBHA-IGRA. This in-house assay identified all the patients that were positive for the TST and showed the best concordance with the presence of a M. tuberculosis exposure risk. During follow-up (median 14 months) no case of active TB was reported and HBHA-IGRA results remained globally constant. Fourteen HIV-infected patients with clinical suspicion of active TB were recruited. Active TB was confirmed for 6 of them among which 3 were HBHA-IGRA positive, each with very high interferon-gamma concentrations. All patients for whom active TB was finally excluded, including 2 non-tubercular mycobacterial infections, had negative HBHA-IGRA results. Multiplex analysis confirmed interferon-gamma as the best read-out. CONCLUSIONS: The HBHA-IGRA appears complementary to the QuantiFERON-TB Gold In-Tube for the screening of latent TB in HIV-infected patients. Large-scale studies are necessary to determine whether this combination offers sufficient sensitivity to dismiss TST, as suggested by our results. Furthermore, HBHA-IGRA may help in the diagnosis work-up of clinical suspicions of active TB.
Assuntos
Infecções por HIV/complicações , Testes de Liberação de Interferon-gama/métodos , Tuberculose Latente/complicações , Tuberculose Latente/diagnóstico , Mycobacterium tuberculosis/isolamento & purificação , Teste Tuberculínico/métodos , Adulto , Idoso , Feminino , Infecções por HIV/epidemiologia , Infecções por HIV/imunologia , HIV-1 , Humanos , Incidência , Interferon gama/análise , Interferon gama/metabolismo , Tuberculose Latente/epidemiologia , Tuberculose Latente/imunologia , Lectinas/metabolismo , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase Multiplex , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/imunologia , Adulto JovemRESUMO
Mycobacterium tilburgii rarely causes disseminated disease. We describe a case of M. tilburgii infection in an otherwise healthy 33-year-old woman, who was found to carry bi-allelic mutations of the gene encoding the ß1 chain of the IL-12 receptor.
Assuntos
Infecções por Mycobacterium não Tuberculosas/genética , Infecções por Mycobacterium não Tuberculosas/imunologia , Receptores de Interleucina-12/deficiência , Adulto , Alelos , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/microbiologia , Linfócitos T CD8-Positivos/patologia , Feminino , Granuloma/tratamento farmacológico , Granuloma/genética , Granuloma/imunologia , Humanos , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/microbiologia , Células Matadoras Naturais/patologia , Linfonodos/imunologia , Linfonodos/microbiologia , Linfonodos/patologia , Mutação/imunologia , Mycobacterium/imunologia , Infecções por Mycobacterium não Tuberculosas/tratamento farmacológico , Receptores de Interleucina-12/genética , RecidivaRESUMO
The new pandemic virus SARS-CoV-2 is characterized by uncontrolled hyper-inflammation in severe cases. As the IL-22/IL-22R1 axis was reported to be involved in inflammation during viral infections, we characterized the expression of IL-22 receptor1, IL-22 and IL-22 binding protein in COVID-19 patients. Blood samples were collected from 19 non-severe and 14 severe patients on the day they presented (D0), at D14, and six months later, and from 6 non-infected controls. The IL-22R1 expression was characterized by flow cytometry. Results were related to HLA-DR expression of myeloid cells, to plasma concentrations of different cytokines and chemokines and NK cells and T lymphocytes functions characterized by their IFN-γ, IL-22, IL-17A, granzyme B and perforin content. The numbers of IL-22R1+ classical, intermediate, and non-classical monocytes and the proportions of IL-22R1+ plasmacytoid DC (pDC), myeloid DC1 and DC2 (mDC1, mDC2) were higher in patients than controls at D0. The proportions of IL-22R1+ classical and intermediate monocytes, and pDC and mDC2 remained high for six months. High proportions of IL-22R1+ non-classical monocytes and mDC2 displayed HLA-DRhigh expression and were thus activated. Multivariate analysis for all IL-22R1+ myeloid cells discriminated the severity of the disease (AUC=0.9023). However, correlation analysis between IL-22R1+ cell subsets and plasma chemokine concentrations suggested pro-inflammatory effects of some subsets and protective effects of others. The numbers of IL-22R1+ classical monocytes and pDC were positively correlated with pro-inflammatory chemokines MCP-1 and IP-10 in severe infections, whereas IL-22R1+ intermediate monocytes were negatively correlated with IL-6, IFN-α and CRP in non-severe infections. Moreover, in the absence of in vitro stimulation, NK and CD4+ T cells produced IFN-γ and IL-22, and CD4+ and CD8+ T cells produced IL-17A. CD4+ T lymphocytes also expressed IL-22R1, the density of its expression defining two different functional subsets. In conclusion, we provide the first evidence that SARS-CoV-2 infection is characterized by an abnormal expression of IL22R1 on blood myeloid cells and CD4+ T lymphocytes. Our results suggest that the involvement of the IL-22R1/IL-22 axis could be protective at the beginning of SARS-CoV-2 infection but could shift to a detrimental response over time.
Assuntos
COVID-19 , Linfócitos T CD8-Positivos , Quimiocinas/metabolismo , Antígenos HLA-DR/metabolismo , Humanos , Inflamação/metabolismo , Interleucina-17/metabolismo , Receptores de Interleucina , SARS-CoV-2RESUMO
The mycolyl transferase antigen 85 complex is a major secreted protein family from mycobacterial culture filtrate, demonstrating powerful T cell stimulatory properties in most HIV-negative, tuberculin-positive volunteers with latent M.tuberculosis infection and only weak responses in HIV-negative tuberculosis patients. Here, we have analyzed T cell reactivity against PPD and Ag85 in HIV-infected individuals, without or with clinical symptoms of tuberculosis, and in AIDS patients with disease caused by nontuberculous mycobacteria. Whereas responses to PPD were not significantly different in HIV-negative and HIV-positive tuberculin-positive volunteers, responses to Ag85 were significantly decreased in the HIV-positive (CDC-A and CDC-B) group. Tuberculosis patients demonstrated low T cell reactivity against Ag85, irrespective of HIV infection, and finally AIDS patients suffering from NTM infections were completely nonreactive to Ag85. A one-year follow-up of twelve HIV-positive tuberculin-positive individuals indicated a decreased reactivity against Ag85 in patients developing clinical tuberculosis, highlighting the protective potential of this antigen.
Assuntos
Infecções Oportunistas Relacionadas com a AIDS/imunologia , Aciltransferases/imunologia , Antígenos de Bactérias/imunologia , Infecções por HIV/imunologia , Infecções por Mycobacterium/imunologia , Linfócitos T/imunologia , Tuberculose/imunologia , Infecções Oportunistas Relacionadas com a AIDS/microbiologia , Bélgica , Guiana Francesa , HIV/fisiologia , Infecções por HIV/complicações , Infecções por HIV/virologia , Humanos , Memória Imunológica , Interferon gama/metabolismo , Ativação Linfocitária/imunologia , Infecções por Mycobacterium/complicações , Mycobacterium tuberculosis/imunologia , Teste Tuberculínico , Tuberculose/complicações , Tuberculose/microbiologia , Tuberculose Pulmonar/complicações , Tuberculose Pulmonar/imunologiaRESUMO
Objectives: To review the current knowledge on screening for latent tuberculosis infection (LTBI) in HIV-infected adults and provide specific guidelines for Belgium. Focus is given to who to test, which testing method to use, timing of screening and choice of LTBI treatment. Methods: Expert review by the members of the Belgian LTBI group, in consultancy with the ARC College. Results: Target population, timing of screening, testing method, active TB exclusion, treatment of LTBI and guideline implementation are all reviewed. Conclusions: The principal changes include a selective approach to screen for LTBI (screening only of the HIV-infected patients at highest risk of active TB) as well as the timing of screening (testing for LTBI performed only after immune-restauration by antiretroviral therapy).
Assuntos
Infecções por HIV , Tuberculose Latente , Programas de Rastreamento , Mycobacterium tuberculosis/isolamento & purificação , Adulto , Terapia Antirretroviral de Alta Atividade/métodos , Bélgica , Feminino , Infecções por HIV/tratamento farmacológico , Infecções por HIV/epidemiologia , Humanos , Incidência , Testes de Liberação de Interferon-gama/métodos , Tuberculose Latente/diagnóstico , Tuberculose Latente/epidemiologia , Tuberculose Latente/terapia , Masculino , Programas de Rastreamento/métodos , Programas de Rastreamento/normas , Administração dos Cuidados ao Paciente/métodos , Administração dos Cuidados ao Paciente/normas , Medição de Risco , Fatores de Risco , Teste Tuberculínico/métodosRESUMO
INTRODUCTION: This study investigates the influence of Mycobacterium tuberculosis infection on immune activation biomarkers, both in HIV-infected and -uninfected subjects. METHODS: Forty-eight treatment-naive HIV-infected patients and 74 HIV-uninfected subjects were recruited and divided into groups according to their M. tuberculosis infection status: latent tuberculosis infection (LTBI), active tuberculosis (TB), and no evidence of M. tuberculosis infection. The expression of cellular markers CD38 and HLA-DR on circulating CD8 T lymphocytes and the plasmatic levels of soluble markers interleukin-6, sCD14, and D-Dimer were measured and compared between groups. The HIV-infected patients with no evidence of M. tuberculosis or with LTBI who initiated antiretroviral treatment were tested again for these biomarkers once viral suppression was reached. RESULTS: In both HIV-infected and -uninfected groups, patients with TB had higher levels of immune activation markers than subjects with LTBI and with no evidence of M. tuberculosis. Among the HIV-uninfected subjects, no significant difference in biomarker level was found between those presenting LTBI and those with no evidence of M. tuberculosis. The effect of LTBI on activation biomarkers in the HIV-infected groups was inconclusive because of the small number of individuals in the HIV+/LTBI group. sCD14 and D-Dimer levels were significantly higher in the TB-only group than in the HIV-only group. DISCUSSION: Although TB is associated with an increase in biomarkers of immune activation, the effect of LTBI is less evident. Further investigation is warranted, and according to our results, soluble markers may offer greater sensitivity for the evaluation of M. tuberculosis-associated immune activation than cellular markers.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Infecções por HIV/complicações , Mycobacterium tuberculosis/imunologia , Subpopulações de Linfócitos T/imunologia , ADP-Ribosil Ciclase 1/análise , Adulto , Linfócitos T CD8-Positivos/química , Feminino , Produtos de Degradação da Fibrina e do Fibrinogênio/análise , Antígenos HLA-DR/análise , Humanos , Interleucina-6/sangue , Receptores de Lipopolissacarídeos/sangue , Masculino , Glicoproteínas de Membrana/análise , Estudos Prospectivos , Subpopulações de Linfócitos T/químicaRESUMO
BACKGROUND: The detection of latent tuberculosis infection (LTBI) is a major component of tuberculosis (TB) control strategies. In addition to the tuberculosis skin test (TST), novel blood tests, based on in vitro release of IFN-gamma in response to Mycobacterium tuberculosis-specific antigens ESAT-6 and CFP-10 (IGRAs), are used for TB diagnosis. However, neither IGRAs nor the TST can separate acute TB from LTBI, and there is concern that responses in IGRAs may decline with time after infection. We have therefore evaluated the potential of the novel antigen heparin-binding hemagglutinin (HBHA) for in vitro detection of LTBI. METHODOLOGY AND PRINCIPAL FINDINGS: HBHA was compared to purified protein derivative (PPD) and ESAT-6 in IGRAs on lymphocytes drawn from 205 individuals living in Belgium, a country with low TB prevalence, where BCG vaccination is not routinely used. Among these subjects, 89 had active TB, 65 had LTBI, based on well-standardized TST reactions and 51 were negative controls. HBHA was significantly more sensitive than ESAT-6 and more specific than PPD for the detection of LTBI. PPD-based tests yielded 90.00% sensitivity and 70.00% specificity for the detection of LTBI, whereas the sensitivity and specificity for the ESAT-6-based tests were 40.74% and 90.91%, and those for the HBHA-based tests were 92.06% and 93.88%, respectively. The QuantiFERON-TB Gold In-Tube (QFT-IT) test applied on 20 LTBI subjects yielded 50% sensitivity. The HBHA IGRA was not influenced by prior BCG vaccination, and, in contrast to the QFT-IT test, remote (>2 years) infections were detected as well as recent (<2 years) infections by the HBHA-specific test. CONCLUSIONS: The use of ESAT-6- and CFP-10-based IGRAs may underestimate the incidence of LTBI, whereas the use of HBHA may combine the operational advantages of IGRAs with high sensitivity and specificity for latent infection.
Assuntos
Hemaglutininas/química , Heparina/química , Interferon gama/metabolismo , Tuberculose/diagnóstico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígenos de Bactérias/química , Feminino , Humanos , Lectinas/química , Masculino , Pessoa de Meia-Idade , Mycobacterium tuberculosis/metabolismo , Teste Tuberculínico , Tuberculose/metabolismoRESUMO
Interleukin-1 (IL-1) is a multifunctional cytokine known to act as a growth factor for AIDS-KS cells. In addition to its mitogenic effects, we found that IL-1 induced the protection of KS cells from apoptotic death induced by serum deprivation in a dose-dependent manner. AIDS-KS cells as well as cells derived from iatrogenic and sporadic KS exhibited a similar response to IL-1, which stresses the key role of this cytokine in the pathogenesis of KS regardless of its epidemiological form. Using both an immunohistochemical and an immunoblot approach, we found that IL-1 increased the expression of Bcl-2 and decreased that of Bax, while having no effect on the expression of Bclx(L), Fas and CD40. The effects of IL-1 were inhibited by IL-1ra, suggesting that imbalance between these two counter-acting cytokines may contribute to the altered accumulation of KS spindle cells. Our findings may provide a link between KS cell escape from apoptosis and the immune dysregulation known to be associated with KS.
Assuntos
Interleucina-1/farmacologia , Proteínas Proto-Oncogênicas c-bcl-2/biossíntese , Proteínas Proto-Oncogênicas/biossíntese , Sarcoma de Kaposi/metabolismo , Sarcoma de Kaposi/patologia , Neoplasias Cutâneas/metabolismo , Neoplasias Cutâneas/patologia , Animais , Apoptose/efeitos dos fármacos , Contagem de Células , Divisão Celular/fisiologia , Ensaio de Unidades Formadoras de Colônias/métodos , Meios de Cultura Livres de Soro/metabolismo , Meios de Cultura Livres de Soro/farmacologia , Relação Dose-Resposta a Droga , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Células-Tronco Neoplásicas/transplante , Células Tumorais Cultivadas , Proteína X Associada a bcl-2RESUMO
BACKGROUND: Kaposi's sarcoma (KS) is a tumor whose ontogenic origin remains a matter of contention. KS tissues are characterized by predominant expression of endothelial markers, while KS-derived cell cultures are usually characterized by expression of mesenchymal non-endothelial cell markers. AIMS: In order to clarify the ontogenic origin of KS cells, we investigated the expression of the fibroblast/macrophage marker 1B10 in KS tissues (AIDS-associated KS, n = 9; classic KS, n = 6; iatrogenic KS, n = 6) and in KS-derived cell cultures. RESULTS: 1B10 was expressed by loosely distributed spindle-shaped cells in early 'patch-stage' KS and by a variable proportion of spindle cells in late 'plaque- and nodular-stage' KS. Using immunohistochemistry and immunoblot analysis, we found that, in vitro, reactivity for 1B10 was uniformly evidenced in fibroblasts and in KS-derived spindle cell cultures, irrespective of their histological or epidemiological setting. By contrast, vascular smooth muscle cells and endothelial cells were negative for 1B10. CONCLUSIONS: These results suggest that the KS spindle cells isolated in vitro may represent a particular subpopulation of the KS spindle cell compartment.
Assuntos
Antígenos de Superfície/biossíntese , Biomarcadores Tumorais/análise , Sarcoma de Kaposi/metabolismo , Neoplasias Cutâneas/metabolismo , Antígenos de Superfície/análise , Biópsia , Fibroblastos/metabolismo , Imuno-Histoquímica , Macrófagos/metabolismo , Sarcoma de Kaposi/patologia , Neoplasias Cutâneas/patologia , Células Tumorais CultivadasRESUMO
Because only 10% of individuals infected with Mycobacterium tuberculosis will eventually develop disease, antigens that are recognized differently by the immune systems of infected healthy and diseased subjects may constitute potential vaccine candidates. Here, the heparin-binding hemagglutinin adhesin (HBHA) is identified as such an antigen. Lymphocytes from 60% of healthy infected individuals (n=25) produced interferon (IFN)-gamma after stimulation with HBHA, compared with only 4% of patients with active tuberculosis (n=24). In the responders, both CD4(+) and CD8(+) cells secreted HBHA-specific IFN-gamma, and the antigen was presented by both major histocompatibility complex class I and II molecules. In contrast to the reduced ability of patients with tuberculosis to produce HBHA-specific IFN-gamma, most of them (82%) produced anti-HBHA antibodies, compared with 36% of the infected healthy subjects. These observations indicate that HBHA is recognized differently by the immune systems of patients with tuberculosis and infected healthy individuals and might provide a marker for protection against tuberculosis.
Assuntos
Linfócitos B/imunologia , Hemaglutininas/imunologia , Mycobacterium tuberculosis/imunologia , Linfócitos T/imunologia , Tuberculose/imunologia , Anticorpos Antibacterianos/biossíntese , Antígenos de Histocompatibilidade Classe I/fisiologia , Antígenos de Histocompatibilidade Classe II/fisiologia , Humanos , Imunofenotipagem , Interferon gama/biossíntese , Lectinas , Tuberculose/tratamento farmacológicoRESUMO
Teams practising medically assisted reproduction techniques try to avoid viruses as much as possible. Attitudes towards chronic carriers of viruses are rapidly changing, especially for human immunodeficiency virus (HIV) patients. We focus our attention on the legitimacy of systematic screening before assisted reproductive techniques and the need for specialized approaches including an adapted laboratory for viral hazards as well as the need for a multidisciplinary team. Specificities of HIV, hepatitis C virus (HCV), hepatitis B virus (HBV) carriers and the hypothesis of a reduced fertility potential are discussed. Are male HIV carriers a new indication for assisted reproductive techniques in order to prevent virus transmission? It is largely proven that sperm gradient preparation techniques efficiently decrease viral loads and therefore have a protective effect on contamination risk during assisted reproductive techniques. Although a few thousand assisted reproductive technique cycles were performed in the world for this indication without contamination, it is still too early to demonstrate that this technology is fully safe. Two examples of contaminations during insemination are examined. Many questions remain unresolved, such as the lack of standardized techniques for semen preparation or virus detection or the relative merits of intrauterine insemination or ICSI to prevent HIV contamination during assisted reproductive techniques. The authors plead for well-structured, separate programmes of care linked to research objectives.
Assuntos
Técnicas de Reprodução Assistida , Viroses/transmissão , Síndrome da Imunodeficiência Adquirida/diagnóstico , Síndrome da Imunodeficiência Adquirida/transmissão , Doença Crônica , Feminino , Soropositividade para HIV , Hepatite B/diagnóstico , Hepatite B/transmissão , Hepatite C/diagnóstico , Hepatite C/transmissão , Humanos , Transmissão Vertical de Doenças Infecciosas , Masculino , Testes Obrigatórios , Gravidez , Técnicas de Reprodução Assistida/ética , Técnicas de Reprodução Assistida/tendências , Doenças Virais Sexualmente Transmissíveis/prevenção & controleRESUMO
Iron is suspected to be involved in the induction and/or progression of various human tumors. More particularly, we have previously shown that iron may be involved in the pathogenesis of Kaposi's sarcoma (KS). We have also shown that the iron chelator desferrioxamine (DFO) has a potent anti-KS activity in vitro, suggesting that it may represent a potential therapeutic approach for the treatment of KS. The present study was designed to investigate the effect of DFO on the growth of human KS xenografts in immunodeficient mice. Unexpectedly, we found that mice treated with DFO (400 mg/kg, 3 times weekly) (n = 30) exhibited a marked enhancement of tumor growth compared with control mice (n = 33) (230 +/- 134 mm(2) versus 143 +/- 70 mm p < 0.01). No enhancement of tumor growth was seen in mice treated with iron-saturated DFO. At least 2 findings suggest that this paradoxic pro-KS activity occurred independently of mice iron stores. First, treatment with DFO had only a marginal effect on ferritin and hematocrit levels. Second, induction of effective iron depletion by an iron-poor diet (6.7 mg iron/kg diet) (n = 23) did not have a deleterious effect on the growth of the KS xenografts. The lesions obtained from the DFO-treated animals exhibited a significantly decreased apoptotic index (p < 0.05), indicating that some antiapoptotic mechanism induced by DFO may be operating in vivo to favour tumor growth. In conclusion, our data show that DFO has a stimulatory effect on KS growth in immunodeficient mice, suggesting that this drug is not indicated in patients with KS.