There is evidence that environmental metal levels affect the immune function. In the particular case of the impact of heavy metals, information available suggests that the immune system is a target for low-dose Pb exposure. Among vertebrates it was shown that amphibians are capable of forming antibodies against a variety of antigens, causing several responses such as anaphylactic response and rejecting grafts. In this study, the production of antibodies was assessed against sheep red blood cells (SRBC) in the anuran Bufo arenarum after six weekly injections of sublethal doses of lead (50 mg.kg-1, as lead acetate). Natural antibodies (natural heteroagglutinins) were also quantified against SRBC. Both assessments were carried out employing an ELISA method developed to this end, measuring absorbance (A). For natural anti-SRBC antibodies in both control (C) and Pb treated (T) toads, there was a non significant tendency to increase the initial absorbances (C initial: 0.69±0.39 A; T initial: 0.54±0.30 A), relative to those registered at the end of the experiments (C final: 0.89±0.49 A; T final: 0.76±0.31A); the T/C ratios also did not show changes. The only significant difference was found between initial and final samples from lead-treated toads (p<0.014). The immune anti- SRBC antibody levels of toads immunized with SRBC showed a significant lower increase (p<0.05) in lead-treated animals (T final: 0.66±0.36 A), as compared to control toads (C final: 0.91±0.50 A) at the end of the experiment. It was thus concluded that the changes due to the assayed doses of Pb in the levels of antibodies cannot be explained on the basis of only one single action mechanism of the metal, but as the result of a conjunction of effects over different immunocompetent cell subpopulations. These different responses suggest that factors affecting animals exposed to a foreign stimulus are different from those influencing the response of wild animals.

Existe evidencia de que los niveles de metal ambientales afectan la función inmune. En el caso particular del impacto de metales pesados, la información disponible sugiere que el sistema inmune es un blanco para la exposición a bajas dosis de Pb. Entre los vertebrados, se ha mostrado que los anfibios son capaces de formar anticuerpos contra una variedad de antígenos, que causan diversas respuestas, tales como respuesta anafiláctica y rechazo de injertos. En este estudio, la producción de anticuerpos fue evaluada contra eritrocitos de oveja (EO) en el anuro Bufo arenarum, luego de seis inyecciones semanales de dosis subletales de plomo (50 mg.kg-1, como acetato de Pb). Los anticuerpos naturales (heteroaglutininas naturales) fueron también cuantificados contra EO. Ambas evaluaciones fueron llevadas a cabo empleando un método de ELISA desarrollado a este fin, midiendo la absorbancia (A). Para los anticuerpos anti-EO naturales, tanto en sapos controles (C) como en sapos tratados con Pb (T), hubo una tendencia significativa a incrementar las absorbancias iniciales (C inicial: 0,69±0,39 A; T inicial: 0,54±0,30 A); la relación T/C tampoco mostró cambios. La única diferencia significativa se encontró entre las muestras inicial y final de los sapos tratados con plomo (p<0,014). Los niveles de anticuerpos anti-EO inmune de sapos inmunizados con EO mostraron un bajo incremento significativo (p<0,05) en los animales tratados con plomo (T final: 0,66±0,36 A), al compararse con sapos control (C final: 0,91±0,50 A) al final del experimento. De este modo, se concluye que los cambios debidos a las dosis analizadas de Pb en los niveles de anticuerpos no pueden explicarse sólo sobre la base de un único mecanismo de acción del metal, sino como resultado de una conjunción de efectos sobre diferentes subpoblaciones de células inmunocompetentes. Estas diferentes respuestas sugieren que los factores que afectan los animales expuestos a un estímulo externo son diferentes de aquellos que influyen la respuesta en los animales silvestres.

The objective of this paper was to evaluate the analytical performance of the laboratories enrolled under Programa de Evaluación Externa de Calidad, Fundación Bioquímica Argentina, Hematology Subprogram (PEEC-H) for the determination of serum iron according to the results of 8 surveys. An average of 6% increase in the levels of acceptance was observed, with respect to the two initial surveys and in relation to those who answered. This figure persisted in the remaining surveys. Contrasting the methods with or without deproteinization for two cromogenic reactants used (ferene and ferozine) from the comparison of their and variances, using a test t and ANOVA, it can be concluded that there were no significant differences (p > 0.05) between both conditions. For the iron analyte, PEEC-H acceptable relative percentage deviation (ARPD) is ± 10%. Between 30 - 40% of the laboratories have an acceptable performance that fits within the ARPD. Bearing these considerations in mind, it is necessary to make a review of the ARPD for the iron analyte used at PEEC-H. Besides, from the analysis of the results, it becomes evident that it is necessary to go on with the Continuing Education to achieve a better standardization of the methodology used, which will result in an improvement in laboratories performance.

El objetivo de este trabajo fue evaluar el desempeño analítico de los laboratorios del Programa de Evaluación Externa de Calidad de la Fundación Bioquímica Argentina, Subprograma Hematología (PEEC-H), para la determinación de hierro sérico según los resultados de 8 encuestas. Se observó un aumento promedio de 6% en los niveles de aceptación, con respecto a las dos encuestas iniciales y en relación a los que responden, que se mantuvo en las encuestas restantes. Contrastando los métodos con y sin desproteinización para dos reactivos cromogénicos empleados (ferene y ferrozina), de la comparación de sus respectivas medias y varianzas mediante test t y ANOVA, se concluye que no hay diferencias significativas (p > 0,05) entre ambas condiciones. En el PEEC-H, para el analito hierro, el desvío porcentual relativo aceptable (DPRA) es de ± 10%. Entre 30 - 45% de los laboratorios tienen un desempeño aceptable que cae dentro del DPRA. Según estas consideraciones, es necesario hacer una revisión del DPRA para el analito hierro empleado en el PEEC-H. Asimismo, del análisis de los resultados surge que se requiere continuar con la Educación Continua para lograr una mayor estandarización en la metodología empleada, que redundará en una mejoría en el desempeño de los laboratorios.

OBJETIVO: Avaliar material de controle para hematologia, de fácil preparação e baixo custo, que poderá ser usado por métodos manuais e automatizados. MATERIAL E MÉTODO: Alíquotas de sangue estabilizado foram preparadas por fixação parcial com aldeídos. Foram estudadas a estabilidade a diferentes temperaturas (4, 20, 37ºC) durante períodos de até 8-9 semanas e a variabilidade das alíquotas para ambos os métodos. RESULTADOS: A variabilidade entre alíquotas, expressada em CV% (coeficiente de variação) com métodos automatizados no primero dia, foi: glóbulos blancos (WBC) 2,7, glóbulos vermelhos (RBC) 0,7, hemoglobina (Hb) 0,6, hematócrito (Hct) 0,7, volume corpuscular médio (MCV) 0,3, Hb corpuscular médio (MCH) 0,3, concentração de Hb corpuscular médio (MCHC) 0,7 e plaquetas (Plt) 4,6. O CV% obtido com métodos manuais para um dos grupos foi: WBC 23, Hct 2,8, Hb 4,5, MCHC 5,9, Plt 41. As amostras conservadas a 4 e 20ºC foram estáveis, observando-se leve hemólise inicial, enquanto que as amostras conservadas a 37ºC mostraram uma rápida decomposição (formação de metaemoglobina, agregação de glóbulos brancos e plaquetas e alteração de índices). CONCLUSÕES: Confirmou-se que, se não houver exposição a altas temperaturas durante a distribuição, este material é estável, permitindo avaliação, tanto externa como interna para controle e com reprodutividade aceitável, tanto para métodos manuais como automáticos.

OBJECTIVE: The assessment of an easy to prepare and low cost control material for Hematology, available for manual and automated methods. MATERIAL AND METHOD: Aliquots of stabilized whole blood were prepared by partial fixation with aldehydes; the stability at different temperatures (4. 20 and 37 °C) during periods of up to 8-9 weeks and aliquot variability with both methods were controlled. RESULTS: Aliquot variability with automated methods at day 1, expressed as CV% (coefficient of variation) was: white blood cells (WBC) 2.7, red blood cells (RBC) 0.7, hemoglobin (Hb) 0.6, hematocrit (Hct) 0.7, mean cell volume (MCV) 0.3, mean cell hemoglobin (MCH) 0.6, mean cell hemoglobin concentration (MCHC) 0.7, and platelets (PLT) 4.6. The CV (coefficient of variation) percentages obtained with manual methods in one of the batches were: WBC 23, Hct 2.8, Hb 4.5, MCHC 5.9, PLT 41. Samples stored at 4ºC and 20ºC showed good stability, only a very low initial hemolysis being observed, whereas those stored at 37ºC deteriobed a rapidly (metahemoglobin formation, aggregation of WBC and platelets, as well as alteration of erythrocyte indexes). CONCLUSIONS: It was confirmed that, as long as there is no exposure to high temperatures during distribution, this material is stable, allowing assessment, both esternal and internal, for control purposes, with acceptable reproductivity, both for manual and auttomatic methods.

OBJETIVO: Avaliar material de controle para hematologia, de fácil preparação e baixo custo, que poderá ser usado por métodos manuais e automatizados. MATERIAL E MÉTODO: Alíquotas de sangue estabilizado foram preparadas por fixação parcial com aldeídos. Foram estudadas a estabilidade a diferentes temperaturas (4, 20, 37ºC) durante períodos de até 8-9 semanas e a variabilidade das alíquotas para ambos os métodos. RESULTADOS: A variabilidade entre alíquotas, expressada em CV% (coeficiente de variação) com métodos automatizados no primero dia, foi: glóbulos blancos (WBC) 2,7, glóbulos vermelhos (RBC) 0,7, hemoglobina (Hb) 0,6, hematócrito (Hct) 0,7, volume corpuscular médio (MCV) 0,3, Hb corpuscular médio (MCH) 0,3, concentração de Hb corpuscular médio (MCHC) 0,7 e plaquetas (Plt) 4,6. O CV% obtido com métodos manuais para um dos grupos foi: WBC 23, Hct 2,8, Hb 4,5, MCHC 5,9, Plt 41. As amostras conservadas a 4 e 20ºC foram estáveis, observando-se leve hemólise inicial, enquanto que as amostras conservadas a 37ºC mostraram uma rápida decomposição (formação de metaemoglobina, agregação de glóbulos brancos e plaquetas e alteração de índices). CONCLUSÕES: Confirmou-se que, se não houver exposição a altas temperaturas durante a distribuição, este material é estável, permitindo avaliação, tanto externa como interna para controle e com reprodutividade aceitável, tanto para métodos manuais como automáticos.

OBJECTIVE: The assessment of an easy to prepare and low cost control material for Hematology, available for manual and automated methods. MATERIAL AND METHOD: Aliquots of stabilized whole blood were prepared by partial fixation with aldehydes; the stability at different temperatures (4. 20 and 37 °C) during periods of up to 8-9 weeks and aliquot variability with both methods were controlled. RESULTS: Aliquot variability with automated methods at day 1, expressed as CV% (coefficient of variation) was: white blood cells (WBC) 2.7, red blood cells (RBC) 0.7, hemoglobin (Hb) 0.6, hematocrit (Hct) 0.7, mean cell volume (MCV) 0.3, mean cell hemoglobin (MCH) 0.6, mean cell hemoglobin concentration (MCHC) 0.7, and platelets (PLT) 4.6. The CV (coefficient of variation) percentages obtained with manual methods in one of the batches were: WBC 23, Hct 2.8, Hb 4.5, MCHC 5.9, PLT 41. Samples stored at 4ºC and 20ºC showed good stability, only a very low initial hemolysis being observed, whereas those stored at 37ºC deteriobed a rapidly (metahemoglobin formation, aggregation of WBC and platelets, as well as alteration of erythrocyte indexes). CONCLUSIONS: It was confirmed that, as long as there is no exposure to high temperatures during distribution, this material is stable, allowing assessment, both esternal and internal, for control purposes, with acceptable reproductivity, both for manual and auttomatic methods.

The assurance of analytical quality in a clinical laboratory is achieved through an internal system of quality control complemented by an external evaluation program. Quality assurance provides a foundation for the confidence that is placed in laboratory results and their use in the diagnosis and treatment of diseases. Many laboratories in Latin American countries do not have appropriate systems in place to evaluate and control quality. Given the importance of diagnoses based on hematologic data, the Pan American Health Organization sponsored a course in quality control in hematology during the XI Latin American Congress of Clinical Biochemistry (Mexico, 1993), in which representatives from Argentina, Chile, Cuba, Mexico, Paraguay, Dominican Republic, and Uruguay participated. As part of the course, the following control materials were produced: secondary standard solution of cyanmethemoglobin, stabilized concentrated hemoglobin solution, and preserved human whole blood with pseudoleukocytes. These materials were sent to laboratories in the seven participating countries for use in analytical procedures, and the results were then subjected to an external evaluation to assess individual performance and the comparability of results among the group. The specific tasks carried out were: (1) determination of values for hemoglobin, hematocrit, and red and white blood cell counts by the procedures normally used in each laboratory; (2) recording of the data on special reporting forms; and (3) transmittal of those forms to the coordinator in each country. The results were analyzed with regard to both the procedure used and the participating country. Reference values were established by consensus following application of a statistical method to eliminate outlying values. Comparative analysis of the results showed the coefficients of variation (CV) of the hematocrit (4.5%), red blood cell count (11.0%), and white blood cell count (22.2%) to be higher than those reported from the United States of America and Europe. With regard to analytical procedures, the manual methods yielded larger CV than the automated methods. When analysis of variance (ANOVA) was used on data broken down by country and by procedure, the only statistically significant result was for leukocyte count (P < 0.02). It was concluded that training in the preparation of quality control materials and the subsequent use of these materials in pilot surveys could provide a starting point for establishing continuous internal and external quality assessment systems in hematology. Such systems, together with continuing education for laboratory personnel and the availablity of automated instrumentation, will lead to achievement of optimum laboratory quality.

La garantía de calidad analítica de un laboratorio clínico se logra mediante un sistema de control de calidad interno complementado por un programa de evaluación externa. Esa garantía es la base que fundamenta la confiabilidad de los resultados obtenidos por los laboratorios y su uso en el diagnóstico y tratamiento de las enfermedades. En los países de América Latina hay muchos laboratorios que no cuentan con sistemas apropiados de evaluación y control de la calidad. Dada la importancia de los diagnósticos basados en datos hematológicos, durante el XI Congreso Latinoamericano de Bioquímica Clínica (México, 1993) la Organización Panamericana de la Salud patrocinó un curso de control de la calidad en hematología en el que participaron Argentina, Chile, Cuba, México, Paraguay, República Dominicana y Uruguay. Como parte del curso se produjeron materiales de control: solución estándar secundario de cianmetahemoglobina (HICN), solución concentrada estabilizada de hemoglobina (Hb) y sangre entera humana preservada con seudoleucocitos. Estos materiales fueron enviados a laboratorios de los siete países participantes para su uso en procedimientos analíticos, con objeto de llevar a cabo posteriormente una evaluación externa del desempeño individual y de la comparabilidad de los resultados en conjunto. Las tareas asignadas fueron: 1) determinación de hemoglobina, hematocrito, y glóbulos rojos y blancos con los métodos en uso en cada laboratorio; 2) registro de los datos obtenidos en formularios especiales para la notificación de datos y 3) envío de dichos formularios al coordinador de cada país. Los resultados fueron analizados en función de los procedimientos analíticos y de los países participantes. Los valores de referencia se establecieron por consenso general de todos los participantes después de someterse al método estadístico de truncamiento. El análisis comparado de los resultados mostró coeficientes de variación (CV) de hematocrito (4,5%), recuento de glóbulos rojos (11,0%) y recuento de glóbulos blancos (22,2%) más altos que los coeficientes obtenidos en los Estados Unidos de América y Europa. En función del procedimiento analítico, los métodos manuales arrojaron CV mayores que los métodos automatizados. Los datos discriminados por país y por procedimiento analítico, sometidos a un análisis de la varianza (ANOVA), mostraron significación estadística solo para el recuento leucocitario (P < 0,02). Se concluye que el adiestramiento en la preparación de materiales de control de calidad y su utilización posterior en encuestas piloto puede constituir la base inicial para establecer sistemas permanentes de evaluación interna y externa de la calidad en hematología que, junto con la educación continua del personal y la disponibilidad de instrumental automatizado, permitan alcanzar el objetivo de calidad óptima en el laboratorio.