Efecto de la ciclofosfamida en la infección por Coccidioides immitis en la rata

Coccidioidomycosis is a systemic mycosis, endemic in arid areas of the American continent. The rat was employed as an experimental host, since it had been shown to reproduce human lesions and present a chronic course of disease with granulomas mainly restricted to lungs. Given the influence of immunosuppressive therapy on the clinical course of human coccidioidomycosis, we studied the effect of cyclophosphamide (CY) in the experimental rat model. Accordingly, animals were inoculated with 400 Coccidioides immitis arthroconidia of the Acosta strain, by intracardiacal route. As single CY doses failed to alter the course of disease, three schedules were used: A) 4 daily doses of 20 mg/kg each, prior to C. immitis inoculation; B) 4 similar daily doses after infection; and C); 6 doses of 20 mg/kg each, given from day +1 to +4, then on days +8 and +9, post infection (pi), taking day 0 as the time of fungal inoculation. The first two schedules inhibited antibody formation up to day 28 pi, without modifying cellular response to coccidioidin as measured by foodpad swelling. Initially, there was greater fungal spread than in controls receiving C. immitis alone, which proved self-limiting in the latter. In contrast, schedule C led to 559r mortality, with both humoral and cellular response abrogation, accompanied by extensive C. immitis dissemination. Histology disclosed significant alterations, such as the persistence of primary infection sporangia, corresponding to the acute stage of coccidioidomycosis in the absence of granuloma development. Therefore, the observed depression in cellular immunity seems responsible for the lack of inflammatory reaction capable of restricting sporangia proliferation in tissues which, in turn, enhances pathogen spread and mortality rate.El propósito de este trabajo fue estudiar el efecto de la inmunosupresión causada por la droga ciclofosfamida (CY) sobre la infección de la rata con Coccidioides immitis por vía intracardíaca. Este huésped fue empleado como modelo experimental, ya que presenta una evolución de la enfermedad semejante a la del hombre, alcanzando una etapa crónica con granulomas principalmente restringidos a los pulmones. Se utilizaron tres esquemas de CY: A) 4 dosis de 20 mg/kg cada una, antes de la inoculación de Ci; B) 4 dosis de igual cantidad de CY, luego de la infección; y C) 6 dosis de 20 mg/kg cada una, administradas desde el día +1 hasta +4 y continuando los días + 8 y +9 post-infección (pi). Los dos primeros esquemas inhibieron la formación de anticuerpos hasta el día 28 pi, sin modificar la respuesta celular a la coccidioidina, medida como hinchazón de la almohadilla plantar. Se observó una mayor diseminación fúngica inicial, autolimi-tándose más tarde. Por el contrario, el esquema C provocó un 55% de mortalidad, disminución de la respuesta humoral y celular, acompañada de una extensa diseminación del Ci. La histología mostró alteraciones significativas, tales como persistencia de esporangios de primoinfección, correspondientes al estadio agudo de la coccidioidomicosis, con ausencia de desarrollo de granulomas. Por lo tanto, la depresión observada en la respuesta celular debido al tratamiento con CY sería la responsable de la ausencia de la reacción inflamatoria capaz de restringir la proliferación de esporangios en los tejidos, lo cual a su vez favorece la diseminación del microorganismo patógeno y el aumento de morta lidad

Coccidioidomicose experimental em ratos imunossuprimidos

C. immitis inoculated rats are known to develop infection restricted to lung whereas cyclophosphamide (CY) treatment leads to widespread dissemination with considerable mortality. In this study, an attempt was made to elucidate the mechanisms involved in such behaviour. With this aim, spleen cells were transferred from infected CY-treated to infected untreated rats, achieving significant specific inhibition in footpad swelling to coccidioidin in recipients, attributable to a suppressor T cell subpopulation induced by greater fungal antigen concentration arising from widespread C. immitis dissemination in immunosuppressed animals. NK activity proved similar regardless of CY treatment. Lastly, chronically infected rats presented increased colony forming units count after several weekly doses of CY, as happens in immunosuppressed patients harbouring a previous infection.Ratos adultos inoculados com C. immitis desenvolveram infecção circunscrita ao pulmão sem apresentar mortalidade; no entanto, ao serem imunossuprimidos com CY apresentaram disseminação fúngica em vários órgãos, ausência de granulomas e depressão na resposta celular à coccidioidina junto com uma mortalidade de 50%. Tentou-se determinar os mecanismos envolvidos neste comportamento. Para isso foram medidas as atividades dos linfócitos supressores e células NK. Ao serem transferidos esplenócitos de animais infectados e tratados com CY a ratos somente infectados conseguiu-se significativa inibição específica da resposta à coccidioidina. Este efeito seria devido a uma subpopulação de linfócitos T supressores induzida por maior concentração de antígeno nos animais imunossuprimidos. A atividade NK foi semelhante nos ratos infectados independentemente do tratamento com CY. Por outro lado, tentou-se a reativação da infecção crônica com C. immitis. Os animais infectados apresentaram maior quantidade de unidades formadoras de colônias nos pulmões depois de várias doses semanais de CY, assim como ocorre em pacientes que apresentam deficiências a nível imunológico

A comprehensive protocol to evaluate the use of blood and its components in Latin America and the Caribbean

Blood transfusion safety is a critical part of appropriate health care. Considering the limited information available on the use of blood and its components in Latin America and the Caribbean, the Grupo Cooperativo iberoamericano de Medicina Transfusional (Ibero-American Cooperative Group for Transfusion Medicine; GCIAMT), through its Research and International Affairs committees, carried out a project to develop a protocol that would facilitate the evaluation of blood usage at the country, jurisdiction, and institutional levels in varied country contexts. Experts in blood safety from the Pan American Health Organization (Washington, DC, United States), the University of São Paulo (São Paulo, Brazil), the Hemocentro of São Paulo (São Paulo, Brazil), and GCIAMT designed a 2-step comprehensive blood-use evaluation protocol: step 1 collects data from blood requests, and step 2, from medical charts. At a minimum, 1 000 analyzed requests are necessary; as such, study periods vary depending on the number of transfusion requests issued. An Internet-based application, the Modular Research System-Study Management System (MRS-SMS), houses the data and produces reports on how hospitals request blood, how blood is issued, who requires blood and blood components, and as an added benefit, how many blood units are wasted and what the real demand for blood is

Estimation of sensitivity and specificity of several Trypanosoma cruzi antibody assays in blood donors in Argentina.

BackgroundThe absence of a gold standard test for Trypanosoma cruzi antibodies represents a problem not only for the evaluation of screening tests, but also for appropriate blood donor counseling. The aim of this study was to estimate the sensitivity and specificity of multiple blood donor screening tests for T. cruzi antibodies in Argentina.Study design and methodsFrom June 2006 to March 2007 a sample of 1455 blood donors was recruited from two blood banks in Chaco province, an area of Argentina with highly endemic T. cruzi infection. Samples were tested by three epimastigote lysate enzyme immunoassays (EIAs), one recombinant antigen EIA, two indirect hemagglutination assay (IHA) tests, a particle agglutination assay (PA), and a research trans-sialidase inhibition assay (TIA). Sensitivity and specificity were estimated using latent class analysis (LCA).ResultsLCA estimated the consensus prevalence of T. cruzi infection at 24.5%. Interassay correlation was higher among the four EIA tests and TIA compared to IHA tests. Assay sensitivities varied from 96 to 99.7 for different EIAs, 91% for TIA, 84% for PA, and 66 to 74% for IHA tests. Relative to the LCA, assay specificities were from 96% to almost 100%.ConclusionBased on the comparison of several tests in a large population from an endemic area for T. cruzi infection, our data showed an adequate sensitivity for EIA tests in contrast to PA and IHA assays. The latter tests should no longer be used for blood donor screening

Estimation of sensitivity and specificity of several Trypanosoma cruzi antibody assays in blood donors in Argentina.

BackgroundThe absence of a gold standard test for Trypanosoma cruzi antibodies represents a problem not only for the evaluation of screening tests, but also for appropriate blood donor counseling. The aim of this study was to estimate the sensitivity and specificity of multiple blood donor screening tests for T. cruzi antibodies in Argentina.Study design and methodsFrom June 2006 to March 2007 a sample of 1455 blood donors was recruited from two blood banks in Chaco province, an area of Argentina with highly endemic T. cruzi infection. Samples were tested by three epimastigote lysate enzyme immunoassays (EIAs), one recombinant antigen EIA, two indirect hemagglutination assay (IHA) tests, a particle agglutination assay (PA), and a research trans-sialidase inhibition assay (TIA). Sensitivity and specificity were estimated using latent class analysis (LCA).ResultsLCA estimated the consensus prevalence of T. cruzi infection at 24.5%. Interassay correlation was higher among the four EIA tests and TIA compared to IHA tests. Assay sensitivities varied from 96 to 99.7 for different EIAs, 91% for TIA, 84% for PA, and 66 to 74% for IHA tests. Relative to the LCA, assay specificities were from 96% to almost 100%.ConclusionBased on the comparison of several tests in a large population from an endemic area for T. cruzi infection, our data showed an adequate sensitivity for EIA tests in contrast to PA and IHA assays. The latter tests should no longer be used for blood donor screening

Experimental coccidioidomycosis in the immunosuppressed rat Coccidioidomicose experimental em ratos imunossuprimidos

C. immitis inoculated rats are known to develop infection restricted to lung whereas cyclophosphamide (CY) treatment leads to widespread dissemination with considerable mortality. In this study, an attempt was made to elucidate the mechanisms involved in such behaviour. With this aim, spleen cells were transferred from infected CY-treated to infected untreated rats, achieving significant specific inhibition in footpad swelling to coccidioidin in recipients, attributable to a suppressor T cell subpopulation induced by greater fungal antigen concentration arising from widespread C. immitis dissemination in immunosuppressed animals. NK activity proved similar regardless of CY treatment. Lastly, chronically infected rats presented increased colony forming units count after several weekly doses of CY, as happens in immunosuppressed patients harbouring a previous infection.<br>Ratos adultos inoculados com C. immitis desenvolveram infecção circunscrita ao pulmão sem apresentar mortalidade; no entanto, ao serem imunossuprimidos com CY apresentaram disseminação fúngica em vários órgãos, ausência de granulomas e depressão na resposta celular à coccidioidina junto com uma mortalidade de 50%. Tentou-se determinar os mecanismos envolvidos neste comportamento. Para isso foram medidas as atividades dos linfócitos supressores e células NK. Ao serem transferidos esplenócitos de animais infectados e tratados com CY a ratos somente infectados conseguiu-se significativa inibição específica da resposta à coccidioidina. Este efeito seria devido a uma subpopulação de linfócitos T supressores induzida por maior concentração de antígeno nos animais imunossuprimidos. A atividade NK foi semelhante nos ratos infectados independentemente do tratamento com CY. Por outro lado, tentou-se a reativação da infecção crônica com C. immitis. Os animais infectados apresentaram maior quantidade de unidades formadoras de colônias nos pulmões depois de várias doses semanais de CY, assim como ocorre em pacientes que apresentam deficiências a nível imunológico