Changes in the levels of free sialic acid during ex vivo lung perfusion do not correlate with pulmonary function. Experimental model.

BACKGROUND: Ex vivo lung perfusion (EVLP) constitutes a tool with great research potential due to its advantages over in vivo and in vitro models. Despite its important contribution to lung reconditioning, this technique has the disadvantage of incurring high costs and can induce pulmonary endothelial injury through perfusion and ventilation. The pulmonary endothelium is made up of endothelial glycocalyx (EG), a coating of proteoglycans (PG) on the luminal surface. PGs are glycoproteins linked to terminal sialic acids (Sia) that can affect homeostasis with responses leading to edema formation. This study evaluated the effect of two ex vivo perfusion solutions on lung function and endothelial injury. METHODS: We divided ten landrace swine into two groups and subjected them to EVLP for 120 min: Group I (n = 5) was perfused with Steen® solution, and Group II (n = 5) was perfused with low-potassium dextran-albumin solution. Ventilatory mechanics, histology, gravimetry, and sialic acid concentrations were evaluated. RESULTS: Both groups showed changes in pulmonary vascular resistance and ventilatory mechanics (p < 0.05, Student's t-test). In addition, the lung injury severity score was better in Group I than in Group II (p < 0.05, Mann-Whitney U); and both groups exhibited a significant increase in Sia concentrations in the perfusate (p < 0.05 t-Student) and Sia immunohistochemical expression. CONCLUSIONS: Sia, as a product of EG disruption during EVLP, was found in all samples obtained in the system; however, the changes in its concentration showed no apparent correlation with lung function.

Clinical, Histological, and Profibrotic Extracellular Matrix Protein Changes in a Model of Tracheal Stenosis Induced by Cervical Tracheal Autotransplantation.

BACKGROUND: Tracheal stenosis (TS) is a complication of prolonged intubation, tracheotomy, and tracheal surgery that compromises the vascular supply. Animal models are essential for studying its pathophysiology and the effect of interventions. OBJECTIVE: To establish a TS model in rats secondary to tracheal autotransplantation with a graft submerged in bleomycin (Atx-Bleo). Additionally, to evaluate the clinical and histological changes, as well as the expression of newly formed collagen (NFC), isoforms of transforming growth factor beta (TGFß), fibronectin (FN), elastin (ELN), integrin ß1 (ITGß1), and matrix metalloproteinase 1 (MMP1) in TS. METHODS: Twenty Wistar rats were divided into three groups: group I (n = 20) control; group II (n = 10) end-to-end anastomosis of the trachea (tracheoplasty); and group III (n = 10) Atx-Bleo. The animals were evaluated clinically, tomographically, macroscopically, morphometrically, and microscopically. NFC deposition, and the expression of profibrotic and antifibrotic proteins were evaluated in tracheal scars. RESULTS: All animals survived the surgical procedure and the study period. Compared with the other study groups, the Atx-Bleo group developed TS and fibrosis, exhibited higher expression of NFC, TGFß1, TGFß2, FN, ELN, and ITGß1, and mild expression of TGFß3 and MMP1 (p < 0.005; analysis of variance, Dunnett and Tukey tests). CONCLUSION: Atx-Bleo in TS model rats produces tomographic and histological changes, and induces the upregulation of profibrotic proteins (TGFß1, TGFß2, collagen, FN, ELN, ITGß1) and downregulation of antifibrotic proteins (TGFß3, MMP1). Therefore, this model may be used to test new pharmacological treatments for reversing or preventing TS, and conduct basic studies regarding its pathophysiology.

Endothelin-Converting Enzyme 1 and Vascular Endothelial Growth Factor as Potential Biomarkers during Ex Vivo Lung Perfusion with Prolonged Hypothermic Lung-Sparing.

Lung transplantation requires optimization of donor's organ use through ex vivo lung perfusion (EVLP) to avoid primary graft dysfunction. Biomarkers can aid in organ selection by providing early evidence of suboptimal lungs during EVLP and thus avoid high-risk transplantations. However, predictive biomarkers of pulmonary graft function such as endothelin-converting enzyme (ECE-1) and vascular endothelial growth factor (VEGF) have not been described under EVLP with standard prolonged hypothermic preservation, which are relevant in situations where lung procurement is difficult or far from the transplantation site. Therefore, this study is aimed at quantifying ECE-1 and VEGF, as well as determining their association with hemodynamic, gasometric, and mechanical ventilatory parameters in a swine model of EVLP with standard prolonged hypothermic preservation. Using a protocol with either immediate (I-) or delayed (D-) initiation of EVLP, ECE-1 levels over time were found to remain constant in both study groups (p > 0.05 RM-ANOVA), while the VEGF protein was higher after prolonged preservation, but it decreased throughout EVLP (p > 0.05 RM-ANOVA). Likewise, hemodynamic, gasometric, mechanical ventilatory, and histological parameters had a tendency to better results after 12 hours of hypothermic preservation in the delayed infusion group.

Treatment with Hyaluronic Acid and Collagen-Polyvinylpyrrolidone Improves Extracellular Matrix Assembly for Scarring after Tracheal Resection.

Treatment of tracheal stenosis is occasionally performed in combination with wound healing modulators to manipulate new extracellular matrix (ECM) formation and prevent fibrosis. Hyaluronic acid (HA) and collagen-polyvinylpyrrolidone (collagen-PVP) decrease fibrosis in experimental tracheal healing. However, they have not been used clinically as their effect on ECM components, which modify tracheal scarring, has not been described. Objective. To evaluate the effect of the application of HA, collagen-PVP, a mixture of HA and collagen-PVP (HA+collagen-PVP), and mitomycin C on the expression of decorin, matrix metalloproteinase 1 (MMP1), and MMP9, as well as the type of collagen and deposits formed in the scar after resection and end-to-end anastomosis (REEA) of the cervical trachea using an experimental model. Materials and Methods. Thirty dogs underwent REEA of the cervical trachea and were treated with different wound healing modulators: group I (n = 6), control; group II (n = 6), HA; group III (n = 6), collagen-PVP; group IV (n = 6), HA+collagen-PVP; and group V (n = 6), mitomycin C. The dogs were evaluated clinically and endoscopically for 4 weeks. Subsequently, macroscopic and microscopic changes, expression of ECM proteins, and collagen deposition in tracheal scars were analysed. Results. Groups II, III, and IV showed reduced endoscopic, macroscopic, and microscopic inflammation, improved neovascularization, high decorin expression (p < 0.01, analysis of variance (ANOVA)), and moderate expression of MMP1 (p < 0.003, ANOVA) and type I and III collagen (p < 0.05, Kruskal-Wallis). Groups IV and V developed fewer collagen deposits (p < 0.001, ANOVA). Conclusion. Treatment with HA and collagen-PVP improved post-REEA healing by increasing neovascularization, stimulating the expression of decorin, and regulating the expression of MMP1, as well as type I and III collagen and their deposition.

Effects of Pirfenidone and Collagen-Polyvinylpyrrolidone on Macroscopic and Microscopic Changes, TGF-ß1 Expression, and Collagen Deposition in an Experimental Model of Tracheal Wound Healing.

Tracheal stenosis (TS) is a fibrosis originated by prolonged inflammation and increased transforming growth factor beta 1 (TGF-ß1) expression and collagen deposition (CD) in the tracheal wound. Several wound-healing modulators (WHMs) have been used to modulate the tracheal healing process and prevent TS, but they have failed, justifying the need to evaluate alternative WHM. The pirfenidone (PFD) and collagen-polyvinylpyrrolidone (Collagen-PVP) decrease inflammation and fibrosis. This study assessed the effect of PFD administration and Collagen-PVP topical application on macroscopic and microscopic changes, TGF-ß1 expression, and CD in an experimental model of tracheal wound healing. Forty Wistar rats underwent cervical tracheoplasty, were divided into 4 groups (n = 10), and were treated with different WHM: group I, saline solution (SS); group II, Collagen-PVP; group III, mitomycin C (MMC); and group IV, 40 mg/kg PFD. Four weeks after surgery, the macroscopic and microscopic changes, in situ TGF-ß1 expression, and CD in posttracheoplasty scars were evaluated. The animals treated with Collagen-PVP and PFD developed less inflammation and fibrosis than animals in the other study groups (p < 0.05, Kruskal-Wallis) and, moreover, showed lower TGF-ß1 expression and CD than animals in group I (p < 0.05, ANOVA and Tukey's test). In conclusion, PFD and Collagen-PVP decrease inflammation, fibrosis, TGFß-1 expression, and CD in the posttracheoplasty rats' scar.

Comparison of lyophilized glutaraldehyde-preserved bovine pericardium with different vascular prostheses for use as vocal cords implants: experimental study.

This study compared the use of lyophilized glutaraldehyde-preserved bovine pericardium (LGPBP), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), and Teflon felt (TF) as implants for vocal cords (VC) medialization and aimed to assess the endoscopic, macroscopic, and microscopic VC changes after medialization in a canine model. In 18 mongrel dogs, the right VC were medialized with LGPBP and the left were implanted as follows: Group I (n = 6): LGPBP and PTFE; Group II (n = 6): LGPBP and PET; Group III (n = 6): LGPBP and TF. Surgical handling of the implants was compared. Three months after surgery, macroscopic and microscopic changes of VC and implants were evaluated. LGPBP offered the best surgical handling (p = 0.005, Kruskal-Wallis). TF implants showed extrusion (p = 0.005, Kruskal-Wallis) and severe inflammation. All VC formed fibrous capsules around the implants; the ones developed by LGPBP implants were thinner (p = 0.001, ANOVA, Tukey). VC implanted with synthetic materials showed eosinophilic infiltration (p = 0.01, Kruskal-Wallis). We concluded that the LGPBP could be used as an implant for VC medialization because it is biocompatible, easy to handle and remove during surgical procedures, and nonabsorbable or extrudable and produces an inflammatory reaction similar to PTFE and PET.

Respiratory mechanics and plasma levels of tumor necrosis factor alpha and interleukin 6 are affected by gas humidification during mechanical ventilation in dogs.

The use of dry gases during mechanical ventilation has been associated with the risk of serious airway complications. The goal of the present study was to quantify the plasma levels of TNF-alpha and IL-6 and to determine the radiological, hemodynamic, gasometric, and microscopic changes in lung mechanics in dogs subjected to short-term mechanical ventilation with and without humidification of the inhaled gas. The experiment was conducted for 24 hours in 10 dogs divided into two groups: Group I (n = 5), mechanical ventilation with dry oxygen dispensation, and Group II (n = 5), mechanical ventilation with oxygen dispensation using a moisture chamber. Variance analysis was used. No changes in physiological, hemodynamic, or gasometric, and radiographic constants were observed. Plasma TNF-alpha levels increased in group I, reaching a maximum 24 hours after mechanical ventilation was initiated (ANOVA p = 0.77). This increase was correlated to changes in mechanical ventilation. Plasma IL-6 levels decreased at 12 hours and increased again towards the end of the study (ANOVA p>0.05). Both groups exhibited a decrease in lung compliance and functional residual capacity values, but this was more pronounced in group I. Pplat increased in group I (ANOVA p = 0.02). Inhalation of dry gas caused histological lesions in the entire respiratory tract, including pulmonary parenchyma, to a greater extent than humidified gas. Humidification of inspired gases can attenuate damage associated with mechanical ventilation.

[Effects of propofol pretreatment on endothelin in oleic acid-induced acute lung injury]. / Efectos del pretratamiento con propofol sobre la endotelina en daño pulmonar agudo inducido por ácido oleico.

INTRODUCTION: Acute lung injury (ALI) is a pathological condition characterized by injury in the alveolar-capillary membrane that triggers local and systemic inflammation. Endothelin (ET) is a protein that regulates immune response and constricts blood vessels; when it is over-expressed, it may contribute to high blood pressure and lung injury. This work tries to determine if propofol may decrease hemodynamic, gasometric, microscopic, ET-1 plasmatic concentration, and immuno-histochemical alterations in an experimental model of oleic acid-induced acute lung injury. MATERIALS AND METHODS. Animals were classified into three groups (n = 6): group I was the control group; in group II, there was oleic acid-induced ALI with no treatment, and group III with propofol pre-treatment and oleic acid-induced ALI. RESULTS: All animals survived until the end of the study, and 100% of group II and group III developed ALI, with hemodynamic, gasometric and gravimetric alterations. However, group III showed less inflammatory infiltration and lower ET-1 expression in lung tissue. CONCLUSIONS: Pretreatment with propofol in a canine model of OA-induced ALI indicates that the drug has anti-inflammatory action, with a potential therapeutic role against progression of anti-inflammation and lung damage.

[Experimental model of canine oleic acid-induced acute lung injury: establishment of a working model]. / Modelo experimental canino de daño pulmonar agudo producido con ácido oleico: estableciendo un modelo de trabajo.

INTRODUCTION: There are several experimental model of acute lung injury induced by oleic acid (OA); however, there are few studies that show how this injury develops. OBJECTIVE: This study seeks to detail the x-ray, hemodynamic, gasometrical, gravimetrical, macroscopic and microscopic alterations developed in an experimental model of canine OA-induced acute lung injury (ALI). MATERIAL AND METHODS: Twelve dogs were divided in 2 study groups: Group I (n=6): Control group without ALI. Group II (n=6); OA-induced ALI. All dogs were submitted to X-ray, hemodynamic and gasometric evaluation before ALI induction, and later every 15 minutes during 150 minutes. At the end of the study, the animals were euthanatized and were evaluated the changes gravimetric, macroscopic and microscopic in injured lungs. RESULTS: All the animals survived through the study. In group II, 100% of the animals developed x-ray (p < 0.003 Wilcoxon), hemodynamic, gasometrical and gravimetric (p < 0.5 ANOVA, Tukey), macroscopically and microscopically (p < 0.001 Wilcoxon) ALI. CONCLUSIONS: The OA-induced ALI is a model in which dogs develop X-ray, hemodynamic, gasometrical, gravimetrical, macroscopically and microscopically injuries of the exudative phase that lung with ALI injury presents.

Lyophilized glutaraldehyde-preserved bovine pericardium for experimental atrial septal defect closure.

A variety of patch materials has been used to close large atrial septal defects (ASD). Autologous pericardium and glutaraldehyde-preserved bovine pericardium are the most used. Lyophilized bovine pericardium has not been tested inside the cardiovascular system. The aim of this work was to study the behaviour and effectiveness of lyophilized glutaraldehyde-preserved bovine pericardium in ASD closure. Sixteen mongrel dogs were operated on. A 3 cm diameter atrial septal defect was created, and closed with: Group I (n=8): Lyophilized glutaraldehyde preserved bovine pericardium (LGPBP). Group II (n=8): Vascular Dacron patch. The animals were evaluated clinically, by echocardiography, macroscopically, and microscopically. Statistical analysis was done with analysis of variance (ANOVA) and Student's t-test. All the animals survived the surgical procedure and study time (6 months). Clinically all the animals displayed normal physical activity, with normal cardiac sounds. Echocardiography showed that both groups had a normal heart without intracardiac shunts, no thrombus formation, and no vegetations. Macroscopically all the animals showed good integration of the lyophilized bioprosthesis and Dacron patch. All group I animals presented a decrease of the area of the ASD in the left atrium (p<0.001 by ANOVA and Student's t-test). Microscopically, group I presented dense and well-organized collagenous tissue, areas of cartilaginous metaplasia and remnants of the lyophilized bioprosthesis (p<0.001 by ANOVA and Student's t-test). Group II showed encapsulated Dacron patch covered with collagenous tissue and cartilaginous metaplasia. In conclusion, the new lyophilized bioprosthesis is well integrated into the atrial septum, without complications and is effective for ASD closure.

Wound healing modulators in a tracheoplasty canine model.

Postsurgical tracheal stenosis results from fibrosis formation due to ischemia. There are healing modulators, hyaluronic acid (HA) and collagen polyvinylpyrrolidone (CPVP), which reduce collagen fibers formation. Thus we can hypothesize that the topical application of one of these modulators can diminish postsurgical tracheal scarring and stenosis. The aim of this work was to evaluate the macroscopic, microscopic, and biochemical changes of tracheal healing after the application of HA or CPVP in a canine tracheoplasty model. The study design was prospective experimental investigation in a canine model. Eighteen mongrel dogs underwent three cervical tracheal rings resection and end-to-end anastomosis. They were randomized into three groups according to treatment: group I (control group) (n = 6), topical application of saline solution on tracheal anastomosis; group II (n = 6), topical application of 15 microg HA on tracheal anastomosis; and group III (n = 6), topical application of 2.5 mg CPVP on tracheal anastomosis. They were evaluated clinical, radiological and tracheoscopically during 4 weeks. They were euthanized at the end of the study time. Macroscopic, microscopic, and biochemical changes of tracheal anastomosis healing were analyzed. Collagen formation was quantified by the Woessner method. All the animals survived the surgical procedure and study period. Macroscopic, radiologic, and endoscopic studies showed that animals in group I developed tracheal stenosis, inflammation, and firm fibrous tissue formation, and histological studies also showed severe inflammatory reaction and fibrosis formation. Groups II (HA) and III (CPVP) showed well-organized thin collagen fibers with minimal inflammatory response. Biochemical evaluation revealed a higher collagen concentration in group I animals (analysis of variance [ANOVA] p < .05 and Tukey p < .01). Thus, hyaluronic acid or collagen polyvinylpyrrolidone administered after tracheal anastomosis diminished the degree of stenosis and inflammatory reaction. Both modulators improved tracheal healing.

Trasplante experimental de tráquea cervical combinado con la aplicación de factor de crecimiento de fibroblastos / Experimental cervical trachea transplant combined with application of basic fibroblast growth factor

Antecedentes: El trasplante traqueal de longitudes mayores a 6 cm de longitud ha fallado por complicaciones isquémicas del injerto. Experimenta/mente se han utilizado factores de crecimiento y diferentes técnicas quirúrgicas, como la de trasplante traqueal dividido para favorecer la neoformación de vasos sanguíneos. Objetivo: Evaluar la viabilidad, cambios tráquea cervical, macroscópicos y microscópicos del trasplante de tráquea cervical en perros al utilizar la técnica quirúrgica de trasplante traqueal dividido, combinando la aplicación del factor básico de crecimiento para fibroblastos en los sitios de las anastomosis. Material y métodos: Se operaron 24 perros que fueron divididos en 4 grupos de estudio: Grupo I (n = 6): Trasplante de 9 anillos de tráquea cervical con la técnica convencional (TTCC); Grupo II (n = 6): TTCC e instilación tópica de factor básico de crecimiento de fibroblastos (bFGF) en los sitios de anastomosis; Grupo III (n = 6): Trasplante con la técnica de trasplante dividido (TTCD) y Grupo IV (n = 6): TTCD y aplicación de bFGF. Los animales recibieron triple inmunosupresión (azatioprina, metilprednisolona, ciclos-porína). Se planearon evaluaciones clínica, radiológica y traqueoscópica durante 4 semanas. Al final del estudio los injertos trasplantados se evaluaron macroscópica y microscópicamente. Resultados: Ningún animal concluyó su tiempo de estudio por disnea grave durante la primera semana del estudio. Macroscópicamente todos los injertos desarrollaron fístulas y necrosis. Microscópicamente mostraron necrosis, inflamación, vasculitis, hemorragia y destrucción del cartílago. Conclusión: En este estudio encontramos que el trasplante de tráquea cervical mayor a 6 cm, tiene malos resultados con la técnica quirúrgica convencional o dividida e inmunosupresión, así como con y sin la aplicación de bFGF en los sitios de anastomosis.

Background: Tracheal transplantation of lesions larger than 6 cm fails due to ischemic complications. Growth factors and different surgical techniques, including the divided tracheal graft technique, have been used experimentally to stimulate the neoformation of blood vessels. Objective: Assessment of the viability and macroscopic and microscopic changes of the cervical transplanted trachea in dogs, using the divided tracheal graft technique, combined with the application of basic fibroblast growth factor (bFGF) on the anastomotic site. Material and methods: Twenty four mongrel dogs were divided in 4 study groups: Group I (n = 6): Transplantation of 9 cervical tracheal rings with the conventional surgical technique (TCTC). Group II (n = 6): TCTC combined with topical instillation of bFGF at on the anastomotic line. Group III (n = 6): Transplantation of cervical trachea using the divided tracheal graft technique (TCTD), and Group IV (n = 6): TCTD with topical application of bFGF. The animals received triple immunotherapy (azathioprine, methylprednisolone, cyclosporine) and were to have clinical, radiological and endoscopical evaluation during 4 weeks. At the end of the study, macroscopic and microscopic evaluations of the transplanted grafts were done. Results: No animal completed the study time due to severe dyspnea during the first postoperative week. Macroscopically all grafts showed necrosis and fistulae formation. Microscopically we observed necrosis, inflammation, vasculitis, hemorrhage and destruction of cartilage in all the grafts. Conclusion: In this study, tracheal allotransplanta-tion longer than 6 cm with either surgical technique, with immunosuppression, with or without bFGF, is unsuccessful.

Cryopreserved tracheal grafts: a review of the literature.

Cryopreserved tracheal grafts have been used in several experimental models of long segment replacement. The clinical application of the procedure has been limited due to the fact that contradictory results have been reported. The purpose of this article is to present a review of the literature on tracheal cryopreservation. Despite the fact that most authors indicate that cryopreserved tracheal allografts retain viability and have a low immunological response, though they continue to function after transplantation with good epithelialization and patency, cryopreservation leads to significant damage to cartilage, the degree of which is based on the freezing-storage methods that affect the function and durability of a graft. The long-term storage of cartilage must therefore be investigated in more detail in basic research models of cartilage viability: the evaluation of chondrocyte apoptosis, and the use of different solutions for tracheal cryopreservation other than RPMI-1640, Dulbecco's modified Eagle's, Eurocollins, and TC-199. Furthermore, problems that involve improving the blood supply to the graft after extensive resection and immunosuppression must be resolved before tracheal cryopreservation can become a clinically established method for tracheal grafts.

Sistema endotelina / Endothelin system

La familia de las endotelinas (ET), está constituida por tres isoformas de 21 aminoácidos: endotelina-1 (ET-1), endotelina-2 (ET-2) y endotelina-3 (ET-3). Las ET son potentes agentes presores endógenos, secretadas por diferentes tejidos y células del organismo. De las tres isoformas, la ET-1 es sintetizada predominantemente por el endotelio vascular. La ET- 1 induce vasoconstricción, es proinflamatoria, profibrosis y tiene acción potencialmente mitógena. Es un importante factor en la regulación del tono vascular y participa en la remodelación vascular. Estos efectos son mediados a través de dos tipos de receptores, ET A y ET B. Los receptores ET A están localizados principalmente en el músculo liso vascular y son responsables de inducir la proliferación celular y vasoconstricción. Los receptores ET B están presentes en las células endoteliales y son mediadores de la relajación vascular por activación de la producción de óxido nítrico y prostaciclina, además, intervienen en la depuración de la ET-1. El sistema endotelina está involucrado esencialmente con la hipertensión arterial sistémica, hipertensión pulmonar, aterosclerosis, reestenosis coronaria, falla cardíaca, cardiomiopatías e insuficiencia renal.

The endothelins (ET S) family consists of three 21 aminoacid isoforms: endothelin-1 (ET-1), endothelin-2 (ET-2) and endothelin-3 (ET-3). ET S are very potent endogenous pressor agents, secreted by various cells and tissues in the human body. Of the three, endothelin-1 is the predominant isoform produced by the vascular endothelium. ET-1 induces vasoconstriction, is proinflammatory, profibrosis, and has mitogenic potential; it is also an important factor in the regulation of vascular tone and arterial vascular remodeling. These effects are mediated via two receptor types, ET A and ET B. ET A receptor is located mainly on vascular smooth muscle and is responsible for mediating vasoconstriction and proliferation. The ET B receptor is present predominantly on endothelial cells and mediates vasorelaxation for NO and prostacyclin release and also ET-1 clearance. The ET system is activated in essential hypertension, pulmonary hypertension, atherosclerosis, coronary restenosis, heart failure, idiopathic cardiomyopathy and renal failure.

Correlación adenosindesaminasa/linfocitos en el líquido pleural de origen tuberculoso / Adenosindeaminase/lymphocyte correlation in pleural liquid of tuberculosis

El presente estudio fue llevado a cabo para evaluar prospectivamente la correlación entre la actividad de la adenosindesaminasa, (ADA) y la proporción de linfocitos en líquido pleural en una región de alta prevalancia de tuberculosis. Durante el periodo de 1991 a 1996 se estudiaron 222 pacientes que ingresaron al Instituto Nacional de Enfermedades Respiratorias con diagnóstico de derrame pleural tuberculoso (TB) y secundario a cáncer (Ca). Hubo 133 TB y 89 Ca, (146 hombres y 76 mujeres). Todos los pacientes fueron diagnosticados con los métodos convencionales. La edad promedio de los pacientes con TB fue 42 ñ 17 y los Ca 61 ñ 13, (-x ñ D.E.). El nivel medio de la actividad de la ADA en el grupo TB (101.6 ñ 41.3 U/L) fue significativamente más alto (p< 0.0001) que en Ca (24.3 ñ 19.1). El porcentaje de linfocitos en el líquido pleural de los pacientes con TB fue 75.5 ñ 16.6 contra 66.8 ñ 17.1 de los Ca (p < 0.0001). La relación entre los niveles de ADA y el porcentaje de linfocitos en líquido pleural de los dos grupos estudiados produjo una significativa curva de regresión (r = 0.750, p< 0.0001), la cual mostró una correlación positiva entre estos dos parámetros. Estos resultados nos sugieren: 1) que la ADA puede ser un buen marcador de inmunidad mediada por células y 2) que existe una buena correlación entre los niveles de ADA y la proporción de linfocitos en líquido pleural tuberculoso