Lucina Titone

Multifunctional CD4+ T cells correlate with active Mycobacterium tuberculosis infection

Th1 CD4+ T cells and their derived cytokines are crucial for protection against Mycobacterium tuberculosis. Using multiparametric flow cytometry, we have evaluated the distribution of seven distinct functional states (IFN‐γ/IL‐2/TNF‐α triple expressors, IFN‐γ/IL‐2, IFN‐γ/TNF‐α or TNF‐α/IL‐2 double expressors or IFN‐γ, IL‐2 or TNF‐α single expressors) of CD4+ T cells in individuals with latent M. tuberculosis infection (LTBI) and active tuberculosis (TB). We found that triple expressors, while detectable in 85–90%TB patients, were only present in 10–15% of LTBI subjects. On the contrary, LTBI subjects had significantly higher (12‐ to 15‐fold) proportions of IL‐2/IFN‐γ double and IFN‐γ single expressors as compared with the other CD4+ T‐cell subsets. Proportions of the other double or single CD4+ T‐cell expressors did not differ between TB and LTBI subjects. These distinct IFN‐γ, IL‐2 and TNF‐α profiles of M. tuberculosis‐specific CD4+ T cells seem to be associated with live bacterial loads, as indicated by the decrease in frequency of multifunctional T cells in TB‐infected patients after completion of anti‐mycobacterial therapy. Our results suggest that phenotypic and functional signatures of CD4+ T cells may serve as immunological correlates of protection and curative host responses, and be a useful tool to monitor the efficacy of anti‐mycobacterial therapy.

Clinical Use of Polymerase Chain Reaction Performed on Peripheral Blood and Bone Marrow Samples for the Diagnosis and Monitoring of Visceral Leishmaniasis in HIV-Infected and HIV-Uninfected Patients : A Single-Center, 8-Year Experience in Italy and Review of the Literature

BACKGROUND To overcome some of the limitations of conventional microbiologic techniques, polymerase chain reaction (PCR)-based assays are proposed as useful tools for the diagnosis of visceral leishmaniasis. PATIENTS AND METHODS A comparative study using conventional microbiologic techniques (i.e., serologic testing, microscopic examination, and culture) and a Leishmania species-specific PCR assay, using peripheral blood and bone marrow aspirate samples as templates, was conducted during an 8-year period. The study cohort consisted of 594 Italian immunocompetent (adult and pediatric) and immunocompromised (adult) patients experiencing febrile syndromes associated with hematologic alterations and/or hepatosplenomegaly. Identification of the infecting protozoa at the species level was directly obtained by PCR of peripheral blood samples, followed by restriction fragment-length polymorphism analysis of the amplified products, and the results were compared with those of isoenzyme typing of Leishmania species strains from patients, which were isolated in vitro. RESULTS Sixty-eight patients (11.4%) had a confirmed diagnosis of visceral leishmaniasis. Eleven cases were observed in human immunodeficiency virus (HIV)-uninfected adults, 20 cases were observed in HIV-infected adults, and the remaining 37 cases were diagnosed in HIV-uninfected children. In the diagnosis of primary visceral leishmaniasis, the sensitivities of the Leishmania species-specific PCR were 95.7% for bone marrow aspirate samples and 98.5% for peripheral blood samples versus sensitivities of 76.2%, 85.5%, and 90.2% for bone marrow aspirate isolation, serologic testing, and microscopic examination of bone marrow biopsy specimens, respectively. None of 229 healthy blood donors or 25 patients with imported malaria who were used as negative control subjects had PCR results positive for Leishmania species in peripheral blood samples (i.e., specificity of Leishmania species-specific PCR, 100%). PCR and restriction fragment-length polymorphism analysis for Leishmania species identification revealed 100% concordance with isoenzyme typing in the 19 patients for whom the latter data were available. CONCLUSIONS PCR assay is a highly sensitive and specific tool for the diagnosis of visceral leishmaniasis in both immunocompetent and immunocompromised patients and can be reliably used for rapid parasite identification at the species level.

Analysis of Mycobacterium tuberculosis-specific CD8 T-cells in patients with active tuberculosis and in individuals with latent infection.

CD8 T-cells contribute to control of Mycobacterium tuberculosis infection, but little is known about the quality of the CD8 T-cell response in subjects with latent infection and in patients with active tuberculosis disease. CD8 T-cells recognizing epitopes from 6 different proteins of Mycobacterium tuberculosis were detected by tetramer staining. Intracellular cytokines staining for specific production of IFN-γ and IL-2 was performed, complemented by phenotyping of memory markers on antigen-specific CD8 T-cells. The ex-vivo frequencies of tetramer-specific CD8 T-cells in tuberculous patients before therapy were lower than in subjects with latent infection, but increased at four months after therapy to comparable percentages detected in subjects with latent infection. The majority of CD8 T-cells from subjects with latent infection expressed a terminally-differentiated phenotype (CD45RA+CCR7−). In contrast, tuberculous patients had only 35% of antigen-specific CD8 T-cells expressing this phenotype, while containing higher proportions of cells with an effector memory- and a central memory-like phenotype, and which did not change significantly after therapy. CD8 T-cells from subjects with latent infection showed a codominance of IL-2+/IFN-γ+ and IL-2−/IFN-γ+ T-cell populations; interestingly, only the IL-2+/IFN-γ+ population was reduced or absent in tuberculous patients, highly suggestive of a restricted functional profile of Mycobacterium tuberculosis-specific CD8 T-cells during active disease. These results suggest distinct Mycobacterium tuberculosis specific CD8 T-cell phenotypic and functional signatures between subjects which control infection (subjects with latent infection) and those who do not (patients with active disease).

Viral gastroenteritis in children hospitalised in Sicily, Italy.

The aim of the present study was to describe the epidemiologic and clinical characteristics of acute viral gastroenteritis in hospitalised Italian children. A total of 215 stool specimens were collected from January to December 2003 from patients hospitalised in Palermo for acute diarrhoea. Samples were tested for group A rotavirus, astrovirus, adenovirus, norovirus, enteropathogenic bacteria, and parasites. Rotaviruses, mostly belonging to types G1–G4, were detected in 25.1% of samples, astrovirus in 7%, adenovirus in 6%, norovirus in 18.6%, and bacterial agents in 17.2%. No parasitic infections were diagnosed. Mixed infections represented 9.8% of all cases. The mean and median ages of children with rotavirus gastroenteritis were lower than those of children with other viruses (p=0.029), with the highest median ages being found in astrovirus-infected patients. Vomiting and dehydration were more frequent among patients with viral infection (p<0.01), and the severity score was significantly higher for children infected with astrovirus or group A rotavirus (p=0.008). Rotavirus was the leading cause of prolonged hospitalisation (p=0.005). In conclusion, viruses were confirmed in Italy as the most common cause of severe enteric illness in childhood, with rotavirus types G1–G4, which correspond to those included in the rotavirus vaccines being developed, playing the main role. Routine testing should be introduced for noroviruses, since they seem to represent an important cause of sporadic paediatric gastroenteritis.

Sequestration of T Lymphocytes to Body Fluids in Tuberculosis: Reversal of Anergy following Chemotherapy

The specificity of CD4 T lymphocytes was investigated in 6 patients affected by tuberculosis who had negative tuberculin purified protein derivative (PPD) skin tests at diagnosis. Polyclonal CD4 T cell lines from the peripheral blood failed to proliferate to PPD and to the 16- or 38-kDa proteins of Mycobacterium tuberculosis, while CD4 cell lines from the disease site responded to PPD and to the 16- and 38-kDa proteins and derived epitopes in vitro. Four months after chemotherapy, the patients became responsive to PPD. The proliferative response to PPD and to the 16- or 38-kDa proteins and their derived peptides decreased in CD4 T cell lines from the disease site and increased in lines from the peripheral blood. These results indicate that CD4 T cells recognizing a vast array of M. tuberculosis epitopes are compartmentalized at the site of disease in anergic patients but appear in peripheral blood after chemotherapy.

Clarithromycin Versus Azithromycin in the Treatment of Mediterranean Spotted Fever in Children: A Randomized Controlled Trial

We conducted an open-label randomized controlled trial to compare the efficacy and safety of clarithromycin (15/mg/kg/day in 2 divided doses for 7 days) with those of azithromycin (10 mg/kg/day in 1 dose for 3 days) in the treatment of children with Mediterranean spotted fever. Until now, there has not been a gold-standard therapy for this rickettsial disease in children. Eighty-seven children were randomized to receive 1 of the 2 drugs. The mean time to defervescence (+/- standard deviation) was 46.2+/-36.4 h in the clarithromycin group and 39.3+/-31.3 h in the azithromycin group. These differences were not statistically significant and both drugs were equally well-tolerated. Clarithromycin and azithromycin could be acceptable therapeutic alternatives to chloramphenicol and tetracyclines for children aged < or =8 years with Mediterranean spotted fever. Azithromycin, because it has a long half-life, offers the advantages of administration in a single daily dose and a shorter duration of therapy, which could increase compliance in children.

Norovirus and Gastroenteritis in Hospitalized Children, Italy

Noroviruses were detected in 48.4% of 192 children (<3 years of age) hospitalized for gastroenteritis in Palermo, Italy, during 2004; predominant genotypes were GGIIb/Hilversum and GGII.4 Hunter. Of children with viral enteritis, 19.6% had a mixed norovirus-rotavirus infection. The severity of infection was lower for norovirus than for rotavirus but increased in co-infection.

Selective Depression of Interferon-γ and Granulysin Production with Increase of Proliferative Response by Vγ9/Vδ2 T Cells in Children with Tuberculosis

Vgamma9/Vdelta2 T cells can contribute to protective immune response against Mycobacterium tuberculosis, although the extent to which and mechanisms by which they could actually protect against human tuberculosis remain unclear. We have previously reported that Vgamma9/Vdelta2 T cells from tuberculin purified protein derivative (PPD)-positive children, either healthy or affected by different clinical forms of tuberculosis, strongly proliferate to different phosphoantigens in vitro, whereas Vgamma9/Vdelta2 T cells from PPD-negative healthy subjects proliferate very poorly. We report here that Vgamma9/Vdelta2 T cells from tuberculous children have an increased proliferative activity, but decreased interferon (IFN)-gamma production and granulysin expression. After successful chemotherapy, the Vgamma9/Vdelta2 T cell proliferative response strongly decreased, whereas IFN-gamma and granulysin production consistently increased. Disease-associated changes in Vgamma9/Vdelta2 T cell effector functions in patients with tuberculosis are consistent with the possibility that these T cells may play a protective role in immune response against M. tuberculosis infection.

Efficacy and Safety of Clarithromycin as Treatment for Mediterranean Spotted Fever in Children: A Randomized Controlled Trial

Fifty-one children with Mediterranean spotted fever (MSF) were randomized to receive either clarithromycin, 15 mg/kg/day orally in 2 divided doses, or chloramphenicol, 50 mg/kg/day orally in 4 divided doses, for 7 days. Mean time to defervescence was 36.7 h in the clarithromycin group and 47.1 h in the chloramphenicol group (P=.047). Clarithromycin could be an acceptable therapeutic alternative to chloramphenicol and to tetracyclines for children aged <8 years with MSF.

Clinical and laboratory findings of boutonneuse fever in Sicilian children.

Abstract The spectrum of signs and symptoms of 645 consecutive children diagnosed from 1984 to 1996 with boutonneuse fever (BF), a mild rickettsial disease caused by Rickettsia conorii endemic in the Mediterranean basin, are reported. The major clinical features were fever (97.2%), exanthema (96.1%) and “tache noire” (71.8%). The large series examined permitted the authors to observe some rare or disregarded clinical features of the disease: cases with papulovesicular exanthema, reported previously only in adults who had been infected by R. conorii in Africa; and cases in which the only symptom was an isolated lymphadenopathy. ConclusionR. conorii infection should be considered in patients with lymphadenopathy who live in or have travelled to an endemic area, even when other, more specific features, are not present. Also pox-like vesicular lesions may be caused by this organism, awaiting confirmation by using culture techniques instead of serology. The serological confirmation of BF by immuno fluorescent antibody test is possible only late in the illness.