RESUMO
BACKGROUND: The expression of B7 as a costimulatory molecule on the surface of antigen-presenting cells such as macrophages and on dendritic cells characterizes the efficiency of the cell-mediated immune response. AIMS: Our purpose was to evaluate B7-1 expression in peripheral blood mononuclear cells (PBMCs) immediately after cell isolation ('spontaneous' B7 expression), and in inflammatory cells from cutaneous lesions of patients with multibacillary leprosy (MB-L) without and during the reactional states of erythema nodosum leprosum (ENL) or reversal reaction (RR). METHODS: Peripheral blood samples and skin biopsies of eight patients without (MB-L) and with reactional episodes (ENL and RR) were studied using antibodies against B7-1, CD1b, DR and CD14 in flow-cytometry and immunohistochemistry experiments. RESULTS: The flow-cytometry studies (mean +/- SD% of fluorescent cells) revealed significant B7-1 expression on PBMCs isolated from patients with ENL (8.0 +/- 0.6%) and RR (15.0 +/- 1.4%) compared with that observed for patients with MB-L (0.4 +/- 0.2%). Similar results were observed for cutaneous lesions of these patients by immunohistochemical assays. One patient studied before and during ENL revealed weak B7 expression before the reactional episode (0.3% of cells) compared with the marked level of B7-expressing cells detected during ENL (8.5% fluorescent cells). Interestingly, an even higher B7 expression (15% of cells) was observed in patients with RR. CONCLUSIONS: Our results strongly suggest that B7 expression precedes reactional episodes in MB-L, which could be related to the acquisition of effective immunity to Mycobacterium leprae during reactional episodes in leprosy. We propose B7 expression as a marker of CMI response in reactional episodes in leprosy.
Assuntos
Antígeno B7-1/imunologia , Hanseníase Virchowiana/imunologia , Leucócitos Mononucleares/imunologia , Citometria de Fluxo , Humanos , Imuno-Histoquímica , Hanseníase Virchowiana/patologiaAssuntos
Hepacivirus/genética , Hepacivirus/isolamento & purificação , Técnicas Imunoenzimáticas/métodos , Programas de Rastreamento/métodos , Diálise Renal , Testes Sorológicos/métodos , Brasil/epidemiologia , Reações Falso-Negativas , Feminino , Genes Virais/genética , Genótipo , Hepatite C/epidemiologia , Hepatite C/virologia , Humanos , Masculino , Reação em Cadeia da Polimerase , Diálise Renal/efeitos adversos , Viremia/virologiaRESUMO
Cell surface expression and release of the tumor necrosis factor receptor (TNFR type I) was analyzed after stimulation of peripheral blood mononuclear cells (PBMC) with Mycobacterium leprae (M. leprae) or lipopolysaccharide (LPS). A transient spontaneous expression of TNFR type I on the surface of PBMC was observed. Two hr after activation with LPS, a significant reduction of TNFR type I expression was detected: Release of TNFR type I by M. leprae or LPS-stimulated PBMC was evaluated with an enzyme-linked immunoabsorbent assay. This release occurred relatively later (20 to 40 hr) than the secretion of TNF alpha which reached high levels between 8 to 20 hr after activation. Thalidomide, a potent drug for the treatment of erythema nodosum leprosum episodes by inhibiting TNF alpha production, had no influence on the TNFR type I expression. Similar results were obtained with pentoxifylline. It is concluded that the release of TNFR type I by M. leprae or LPS-stimulated PBMC may counteract the pro-inflammatory activities of TNF alpha, by reducing the systemic toxicity of this cytokine in leprosy.
Assuntos
Leucócitos Mononucleares/imunologia , Lipopolissacarídeos/imunologia , Mycobacterium leprae/imunologia , Receptores do Fator de Necrose Tumoral/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Células Cultivadas , Depressão Química , Humanos , Leucócitos Mononucleares/metabolismo , Talidomida/farmacologiaRESUMO
Aproxidamente 400 pacientes de hemodialise tratados em 5 diferentes unidades no Rio de Janeiro foram acompanhados durante 1 ano para presenca de marcadores virais de hepatite B e C. Durante o mesmo periodo, amostras foram tambem de 35 pacientes ambulatoriais de dialise peritonial continua (CAPD) e de 242 funcionarios das unidades. Dependendo da unidade em estudo foram detectadas prevalencias de anti-HCV variando de 47 por cento a 82 por cento (media 65 por cento ). Pacientes de prevalencia de anti-HCV em funcionarios foi de 2,9 por cento . Observamos uma taxa de ataque de hepatite C de 11,5 por cento por ano na populacao paciente de hemodialise anti-HCV negativo. Uma media de 9,4 por cento de pacientes de hemodialise eram portadores cronicos do virus da hepatite B (VHB) (taxa de 1.8 por cento a 20.4 por cento ), enquanto 48.9 por cento apresentaram marcadores de infeccao passada de HBV. A taxa de ataque de HBV foi de 4.5 por cento por ano (taxa de 0 por cento a 6 por cento ). Esses resultados indicam uma alarmante prevalencia alta anti-HCV em pacientes de hemodialise dessa regiao estudada.
Assuntos
Humanos , Diálise Renal/efeitos adversos , Hepatite C/transmissão , Brasil , Seguimentos , Hepatite C/epidemiologia , Fatores de RiscoRESUMO
Nearly 400 hemodialysis patients treated at 5 different hemodialysis units in Rio de Janeiro were tested for one year for the presence of hepatitis C and B markers. During the same period, samples were also obtained from 35 continuous ambulatory peritoneal dialysis (CAPD) patients and from 242 health care workers. Depending on the hemodialysis unit studied, anti-HCV prevalence rates ranging from 47% to 82% (mean 65%) were detected. CAPD patients showed a lower prevalence of 17%. The prevalence of antibodies against hepatitis C virus (anti-HCV) among health care workers was 2.9%. We observed a hepatitis C attack rate of 11.5% per year in the anti-HCV-negative hemodialysis patient population. An average of 9.4% of the hemodialysis patients were chronic carriers of hepatitis B virus (HBV) (range 1.8% - 20.4%), while 48.9% showed markers of previous HBV infection. The HBV attack rate was 4.5% per year (range 0% - 6%). These results indicate an alarming high prevalence of anti-HCV among hemodialysis patients of this studied region.
Assuntos
Hepatite B/epidemiologia , Hepatite C/epidemiologia , Diálise Renal , Brasil/epidemiologia , Hepatite B/diagnóstico , Hepatite C/diagnóstico , Humanos , Diálise Peritoneal Ambulatorial Contínua , Prevalência , Fatores de RiscoRESUMO
The sequences of two minicircles from the kinetoplast DNA of the CL strain and one of the Y strain of Trypanosoma cruzi are reported. These 1.4 kb molecules have a peculiar sequence organization, the most distinctive feature being the occurrence of a 120 bp sequence repeated four times, located at 0, 90, 180 and 270 degrees along each circle. We have termed these conserved regions in this species 'minirepeats'. Minirepeats have a 3-fold higher concentration of cytosine residues in comparison with the variable regions and contain the universal 12-mer motif GGGGTTGGTGTA present in all sequenced minicircles and which was shown to be involved in DNA replication. A consensus sequence of T. cruzi minirepeats was determined using the 20 minirepeats present in five known T. cruzi minicircle sequences. This consensus sequence contains regions which have been remarkably well preserved in strains which show great biological diversity. In addition a low level of intraminicircle sequence similarity was also observed within the variable region, but this similarity did not extend between strains. The abundance of conserved minirepeat sequences containing invariant restriction sites in T. cruzi cells may prove valuable for the development of new direct diagnostic methods for Chagas' disease based on DNA probe technology.