ABSTRACT
BACKGROUND: There is no recommendation for treating pulmonary hypertension (PH) when associated with chronic obstructive pulmonary disease (COPD). OBJECTIVE: To evaluate the effect of PH-specific therapy in patients with COPD. METHODS: All successive patients with severe PH [mean pulmonary arterial pressure (mPAP) ≥35 mm Hg] and COPD, who received specific PH medication and who underwent right heart catheterization at baseline and after 3-12 months of treatment, were analyzed from a prospective database. RESULTS: Twenty-six patients were included with a median follow-up of 14 months. Mean forced expiratory volume in 1 s was 57 ± 20% of predicted, and mean forced expiratory volume in 1 s/forced vital capacity was 47 ± 12%. Dyspnea was New York Health Association classification stage (NYHA) II in 15%, NYHA III in 81% and NYHA IV in 4%. First-line treatments were endothelin receptor antagonists in 11 patients, phosphodiesterase-5 inhibitors in 11 patients, calcium blocker in 1 patient, combination therapy in 3 patients including 2 with a prostanoid. After 6 ± 3 months, pulmonary vascular resistance decreased from 8.5 ± 3 to 6.6 ± 2 Wood units (p < 0.001), with significant improvement of cardiac index from 2.44 ± 0.43 to 2.68 ± 0.63 liters × min × m-2 (p = 0.015) and mPAP from 48 ± 9 to 42 ± 10 mm Hg (p = 0.008). There was no significant difference in dyspnea, 6-min walking distance, echocardiographic parameters or N-terminal pro-brain natriuretic peptide levels. There was no significant difference in arterial oxygen saturation after 3-12 months of treatment. CONCLUSIONS: Specific PH medications may improve hemodynamic parameters in COPD patients with severe PH. Appropriate prospective randomized studies are needed to evaluate the potential long-term clinical benefit of treatment.
Subject(s)
Hypertension, Pulmonary/drug therapy , Hypertension, Pulmonary/epidemiology , Pulmonary Disease, Chronic Obstructive/drug therapy , Pulmonary Disease, Chronic Obstructive/epidemiology , Vascular Resistance/drug effects , Aged , Bosentan , Cohort Studies , Comorbidity , Female , Follow-Up Studies , France , Hemodynamics/physiology , Hospitals, University , Humans , Hypertension, Pulmonary/diagnosis , Male , Middle Aged , Pulmonary Disease, Chronic Obstructive/diagnosis , Retrospective Studies , Severity of Illness Index , Sildenafil Citrate/therapeutic use , Statistics, Nonparametric , Sulfonamides/therapeutic use , Treatment Outcome , Vasodilator Agents/therapeutic useABSTRACT
Airway-centered interstitial fibrosis (ACIF) is a distinct type of lung interstitial fibrosis characterized by lesions centered on the airways. Several cases reported in the literature showed little to no effect of corticosteroids and a high mortality rate in the absence of lung transplantation. No other efficient approach is described for the treatment of this type of fibrosis. We report for the first time the case of a 44-year-old patient diagnosed with ACIF on surgical lung biopsy and stabilized with clarithromycin after failure of systemic corticosteroids. We need to confirm this benefit in other patients to ascertain the anti-inflammatory effect of macrolides, which are far less harmful compared to corticosteroids or immunosuppressant drugs.
Subject(s)
Anti-Bacterial Agents/therapeutic use , Clarithromycin/therapeutic use , Lung Diseases, Interstitial/drug therapy , Pulmonary Fibrosis/drug therapy , Adult , Enzyme Inhibitors , Esomeprazole/adverse effects , Glucocorticoids/adverse effects , Humans , Lung Diseases, Interstitial/diagnostic imaging , Male , Prednisolone/adverse effects , Pulmonary Fibrosis/pathology , Radiography , Respiratory Function Tests , Treatment FailureABSTRACT
OBJECTIVE: To compare the one year survival after discharge from ICU of patients with chronic obstructive pulmonary disease (COPD) admitted for acute hypercapnic respiratory failure and who required mechanical ventilation. METHODS: Retrospective cohort study on 130 patients, 52 patients were treated with non-invasive ventilation (NIV) and 78 patients with conventional mechanical ventilation (CMV). RESULTS: In 73 patients the cause for respiratory failure could not be identified. Long-term survival was significantly better following NIV than with CMV (p=0.02 by log-rank testing), but the better prognosis associated with use of NIV was not found in patients with no documented cause for the respiratory failure. After adjusting for male gender, age>65 years, simplified acute physiology score II>35, prior long-term home oxygen therapy, treatment with steroids, FEV1<30% of predicted value, body-mass index<21 kg/m2, albumin level<30 g/L, right ventricular failure, ventilator-associated pneumonia and cause of respiratory failure, NIV remained independently associated with better outcomes (adjusted hazard ratio 0.55; 95% CI 0.31-0.97; p=0.04). CONCLUSIONS: Our results suggest that in COPD patients requiring mechanical ventilation and who survived after an ICU stay, the use of NIV is an independent factor associated with a better long-term survival, especially in those with a documented cause of respiratory failure.
Subject(s)
Pulmonary Disease, Chronic Obstructive/mortality , Pulmonary Disease, Chronic Obstructive/therapy , Respiration, Artificial/methods , Aged , Cohort Studies , Female , France/epidemiology , Humans , Intensive Care Units , Male , Middle Aged , Retrospective StudiesABSTRACT
BACKGROUND: After stopping a 3 to 6 months course of oral anticoagulation for a first episode of idiopathic venous thromboembolism (VTE), the risk of recurrent VTE is high (10% per year). In this setting, international guidelines recommend at least 6 months treatment. However, this recommendation is not satisfactory for the following reasons: (1) no randomized trial has compared 6 months to extended duration (2 years) anticoagulation; and (2), even though the frequency of recurrent VTE is similar after pulmonary embolism (PE) and deep vein thrombosis (DVT), the fatality rate of recurrent VTE after PE is higher than that after DVT. METHODS: A French multicentre double blind randomized trial. The main objective is to demonstrate, after a first episode of symptomatic idiopathic PE treated for 6 months using a vitamin K antagonist, that extended anticoagulation for 18 months (INR between 2 and 3) is associated with an increased benefit / risk ratio (recurrent VTE and severe anticoagulant-related bleeding) compared to placebo. The double blind evaluation is ensured using by active warfarin and placebo, and blinded INR. The protocol was approved by the ethics board of the Brest Hospital on the 7th of March 2006. For an alpha risk of 5% and a beta risk of 20%, the estimated sample size is 374 patients. EXPECTED RESULTS: This study has the potential to: (1) demonstrate that the benefit / risk ratio of extended anticoagulation for 18 months is higher than that observed with placebo in patients with a first episode of idiopathic PE initially treated for 6 months, during and after the treatment period; and (2) to validate or invalidate the contribution of isotope lung scans, lower limb Doppler ultrasound and D-Dimer at 6 months of treatment as predictors of recurrent VTE (medico-economic analysis included).
Subject(s)
Anticoagulants/therapeutic use , Pulmonary Embolism/drug therapy , Venous Thromboembolism/drug therapy , Vitamin K/antagonists & inhibitors , Warfarin/therapeutic use , Anticoagulants/administration & dosage , Anticoagulants/adverse effects , Chi-Square Distribution , Data Interpretation, Statistical , Double-Blind Method , Hemorrhage/chemically induced , Humans , Placebos , Practice Guidelines as Topic , Prognosis , Recurrence , Risk Assessment , Time Factors , Warfarin/administration & dosage , Warfarin/adverse effectsSubject(s)
Gastrointestinal Agents/therapeutic use , Idiopathic Pulmonary Fibrosis/drug therapy , Octreotide/therapeutic use , Aged , Aged, 80 and over , Biomarkers/blood , Female , France , Gastrointestinal Agents/adverse effects , Humans , Idiopathic Pulmonary Fibrosis/physiopathology , Male , Middle Aged , Octreotide/adverse effects , Octreotide/blood , Respiratory Function Tests , Severity of Illness Index , Treatment FailureABSTRACT
The beta-blocker (BB) prescription remains insufficient despite guidelines, especially, for chronic heart failure. Patients suffering chronic obstructive pulmonary disease (COPD) are particularly less treated by BB. The level of evidence for BB prescription is however especially high and as we will focus on, the level of evidence for the safety of BB in the COPD context is convincing enough. We, thus, propose to review the existing literature in regard to this prescription of BB in the chronic heart failure, in the coronary artery disease and for high blood pressure in COPD patients. We then propose our approach to improve the level of prescription of BB in COPD patient really justifying this prescription in cardiology.
Subject(s)
Adrenergic beta-Antagonists/therapeutic use , Coronary Artery Disease/complications , Coronary Artery Disease/drug therapy , Heart Failure/complications , Heart Failure/drug therapy , Hypertension/complications , Hypertension/drug therapy , Pulmonary Disease, Chronic Obstructive/complications , Chronic Disease , HumansABSTRACT
INTRODUCTION: Auto-immune pulmonary alveolar proteinosis is a rare disorder characterized by the accumulation of surfactant proteins in the alveoli. CASE REPORT: We report a case of a 41-year-old smoker, presenting initially with acute respiratory failure. Whole lung lavages were effective initially but only for a few weeks. GM-CSF subcutaneous injections were not effective, and then plasmapheresis were tried. CONCLUSION: This is the fifth report of the use of this treatment in auto-immune pulmonary alveolar proteinosis. Plasmapheresis was not effective in our patient.
Subject(s)
Autoimmune Diseases/therapy , Plasmapheresis , Pulmonary Alveolar Proteinosis/therapy , Adult , Autoimmune Diseases/diagnosis , Autoimmune Diseases/pathology , Humans , Male , Pulmonary Alveolar Proteinosis/diagnosis , Pulmonary Alveolar Proteinosis/pathology , Radiography, Thoracic , Respiratory Distress Syndrome/diagnosis , Respiratory Distress Syndrome/etiology , Respiratory Distress Syndrome/pathology , Respiratory Distress Syndrome/therapy , Treatment FailureSubject(s)
Inflammation/immunology , Threonine-tRNA Ligase/immunology , Adult , Aged , Antibodies , Cell Line , Echocardiography/methods , Female , Humans , Male , Middle Aged , Myositis/blood , Myositis/immunology , Phenotype , Prevalence , Prognosis , Retrospective StudiesABSTRACT
PURPOSE: To evaluate the efficacy and safety of paclitaxel and carboplatin in the treatment of previously untreated patients with metastatic small-cell lung cancer (SCLC). PATIENTS AND METHODS: Eligible patients were aged 18 to 75 years with an Eastern Cooperative Oncology Group (ECOG) score < or = 2 and life expectancy > or = 12 weeks. Paclitaxel (200 mg/m(2)) was infused over 3 hours, before carboplatin (area under the curve [AUC] 6; Calvert formula) infused over 1 hour, once every 3 weeks for six cycles maximum. Prednisolone, dexchlorpheniramine, and ranitidine were standard premedication. Response to treatment was assessed every two cycles, and nonresponding patients were withdrawn from the trial to receive standard chemotherapy. RESULTS: Of the 50 patients entering the study, 48 and 46 patients were assessable for toxicity and response, respectively. The overall response rate was 65%, with complete responses in three patients. Five patients had stable disease (11%) and 11 patients experienced progressive disease (24%). Median survival was 38 weeks, and median duration of response was 20 weeks. One-year survival was 22.5%. For a total of 232 cycles, grade 3 and 4 toxicity was 33% for neutropenia, 3.5% for thrombocytopenia, and 4% for anemia. Four patients had neutropenic fever (one toxic death). Nonhematologic toxicity was mainly grade 1 and 2 paresthesia (21% of patients); grade 3 myalgia/arthralgia was observed in 6.5% of patients. CONCLUSION: First-line chemotherapy with paclitaxel and carboplatin in metastatic SCLC achieved a response rate and survival similar to standard regimens. With 1-day administration and a tolerable toxicity profile, this combination merits further investigation.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Carcinoma, Small Cell/drug therapy , Lung Neoplasms/drug therapy , Adult , Aged , Anemia/chemically induced , Carboplatin/administration & dosage , Carboplatin/adverse effects , Carcinoma, Small Cell/secondary , Female , Humans , Lung Neoplasms/pathology , Male , Middle Aged , Neoplasm Metastasis , Neutropenia/chemically induced , Paclitaxel/administration & dosage , Paclitaxel/adverse effects , Survival Analysis , Thrombocytopenia/chemically induced , Treatment OutcomeABSTRACT
OBJECTIVES: To study the frequency of a factor of immunodepression in patients with tuberculosis, the differences in presentation, and the diagnosis and therapeutic management according to the immune status. METHODS: Retrospective study of the files of patients hospitalised in the University Hospital Centre of Rennes in 1998 for a Mycobacterium tuberculosis infection. Comparison of two populations, immunodepressed versus non immunodepressed. RESULTS: 75 patients aged 20 to 91 were included, 41 patients were considered immunodepressed and 34 non immunodepressed. The causes of immunodepression were: HIV infection (n = 2), diabetes (n = 4), chronic alcoholism (n = 12), chronic respiratory diseases treated with corticosteroids (n = 6), neoplasia (n = 9), and inflammatory diseases (n = 7). Comparison between the 2 populations revealed more a frequent history of tuberculosis in the immunodepressed (p = 0.04), shorter delay before diagnosis (p = 0.04), greater frequency of disseminated forms (p = 0.02) and enhanced mortality (p = 0.01). There was no difference in the 2 groups with regard to the clinical signs having evoked tuberculosis, the diagnostic method, the bacteriological results or the modalities of treatment. CONCLUSION: The frequent reactivation of tuberculosis in immunodepressed patients and the severity of the infection in these patients should evoke tuberculosis and the rapid initiation of an efficient treatment in such patients. In the case of alteration in immune defences, prophylactic treatment should help to reduce the number of such reactivations.
Subject(s)
Immunocompromised Host , Tuberculosis, Pulmonary/complications , Tuberculosis, Pulmonary/immunology , Adult , Aged , Aged, 80 and over , Female , HIV Infections/complications , Humans , Male , Middle Aged , Retrospective StudiesABSTRACT
INTRODUCTION: Alpha-1 antitrypsin, secreted by the liver, inhibits neutrophil elastase. Its deficiency favours the development of emphysema. Restoring a "protective" serum level in deficient patients should make it possible to inhibit the development of emphysema. STATE OF THE ART: Human plasma-derived alpha-1 antitrypsin is a blood-derived drug sold in France under the name Alfalastin(®). The recommended posology is an I.V. administration of 60 mg/kg once a week. Human plasma-derived alpha-1 antitrypsin restores anti-elastase protection in the lower lung and prevents experimental emphysema induced by the elastasis of human neutrophils in hamster. The low number of patients with alpha-1 antitrypsin deficiency is one of the difficulties to perform sufficiently powerful randomised studies. However, randomised studies have reported the efficacy of human plasma-derived alpha-1 antitrypsin perfusions on mortality, FEV1 decline and the frequency of exacerbations. Randomised control trials have demonstrated the efficacy of human plasma-derived alpha-1 antitrypsin perfusions on the loss of lung density assessed by CT scan. CONCLUSION: Augmentation therapy is simple in its conception and implementation, but it is expensive. However, there are currently no other solutions.
Subject(s)
Pulmonary Emphysema/drug therapy , alpha 1-Antitrypsin Deficiency/drug therapy , alpha 1-Antitrypsin/therapeutic use , Animals , Drug Synergism , Humans , Lung/drug effects , Lung/pathologyABSTRACT
Antisynthetase syndrome is an inflammatory myopathy frequently associated with pulmonary manifestations, especially interstitial lung diseases, and uncommonly pulmonary hypertension. In the context of a suggestive clinical and radiological picture, positive anti-RNA synthetase antibodies confirm the diagnosis. Anti-Jo1, anti-PL7, and anti-PL12 antibodies are the more commonly encountered. The presence of a number of extra-thoracic manifestations in association with pulmonary disease may suggest the diagnosis. These include: myalgia or muscular deficit, Raynaud's phenomenon, polyarthritis, fever, mechanics hands. Serum creatine kinase levels are usually increased. Electromyogram, muscular magnetic resonance imaging or muscle pathology are not mandatory to make the diagnosis. There is a high variability in symptoms and severity, between patients but also during the course of the disease in the same patient. The presence of an interstitial lung disease is a major prognostic factor and an indication for more intensive treatment, principally with systemic corticosteroids with or without immunosuppressive drugs. Improving respiratory physicians' knowledge of this disease, which is often revealed by its pulmonary manifestations, should help diagnosis, therapeutic management, and possibly prognosis.
Subject(s)
Hypertension, Pulmonary/etiology , Lung Diseases, Interstitial/etiology , Myositis/complications , Disease Progression , Humans , Hypertension, Pulmonary/diagnosis , Hypertension, Pulmonary/epidemiology , Lung Diseases, Interstitial/diagnosis , Lung Diseases, Interstitial/epidemiology , Myositis/diagnosis , Myositis/epidemiology , Prognosis , Radiography, Thoracic , Raynaud Disease/diagnosis , Raynaud Disease/epidemiology , Raynaud Disease/etiologyABSTRACT
A method of direct quantitation of 67Ga uptake in the lung is described. The attenuation coefficient requires calculation and is obtained simply for each patient by transmission using a planar radionuclide source. The validity of the method was tested with a phantom (error less than 10%). Forty-three patients with pulmonary and/or mediastinal sarcoidosis were classified. The different groups of patients as defined clinically and radiographically (controls, nonactive, and active sarcoidosis) were well-differentiated (p less than 0.001).
Subject(s)
Gallium Radioisotopes , Lung Diseases/diagnostic imaging , Sarcoidosis/diagnostic imaging , Adult , Female , Humans , Male , Methods , Radionuclide ImagingABSTRACT
A case is presented of sarcoid myopathy in which radiogallium was seen to accumulate in the sites of muscle involvement. Uptake of the radiotracer disappeared following institution of corticosteroid therapy. The exceptional nature of this case contrasts with the high frequency of biopsy evidence of sarcoid muscle disease but is consistent with the rarity of clinical evidence of sarcoid granulomas in muscle. Gallium-67 imaging can be used to determine the extent of muscle involvement and, through evaluation of uptake intensity, the degree of disease activity before and after treatment.
Subject(s)
Gallium Radioisotopes , Muscular Diseases/diagnostic imaging , Sarcoidosis/diagnostic imaging , Adult , Humans , Male , Radionuclide ImagingABSTRACT
We report a fatal case of acute interstitial pneumonitis in a patient treated with carmustine (BCNU) for a brain tumor. Bronchoalveolar lavage (BAL) revealed lymphocyte alveolitis with a low CD4/CD8 ratio (0.36), consistent with an immunoallergic phenomenon, rather than the most often evoked toxic hypothesis.
Subject(s)
Carmustine/adverse effects , Lung Diseases, Interstitial/chemically induced , Acute Disease , Adult , Brain Neoplasms/drug therapy , Fatal Outcome , Humans , Lung Diseases, Interstitial/diagnostic imaging , Male , RadiographyABSTRACT
PURPOSE: to compare standard and alternating administration of chemotherapy combinations in small cell lung cancer (SCLC) patients. MATERIAL AND METHODS: in a multicenter clinical trial, 394 previously untreated SCLC patients were randomised to receive, every 4 weeks, eight courses of either a standard regimen with CCNU, cyclophosphamide, adriamycin (CCA) and VP16 or an alternating regimen (CCA regimen alternating with cisplatin-vindesine-VP16). RESULTS: overall response rate was higher in the standard group (78%) than in the alternating group (64%) (P = 0.0001). Complete response rate was also higher in the standard group (32%) than in the alternating group (18%) (P = 0.004). The median survival in the overall SCLC population was 306 days in the standard group and 272 days in the alternating group (P = 0.08). In limited SCLC patients, median survival was higher in the standard group (421 days) than in the alternating group (328 days) (P = 0.01). Grade III/IV haematological toxicity was lower in patients in the alternating group (25 versus 47%) (P < 0.001). CONCLUSION: the standard regimen was better than the alternating regimen for patients with limited forms of SCLC. The alternating regimen, associated with better haematological safety and ensuring a fairly similar survival, may be considered in patients with extensive SCLC. Pleiomorphic resistance mechanisms to chemotherapy make it difficult to define a non-cross-resistant chemotherapy regimen.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/administration & dosage , Carcinoma, Small Cell/drug therapy , Lung Neoplasms/drug therapy , Adult , Aged , Aged, 80 and over , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Carcinoma, Small Cell/mortality , Cyclophosphamide/administration & dosage , Doxorubicin/administration & dosage , Drug Administration Schedule , Drug Resistance, Neoplasm , Etoposide/administration & dosage , Female , Heparin/therapeutic use , Humans , Lomustine/administration & dosage , Lung Neoplasms/mortality , Male , Middle Aged , Prospective Studies , Survival RateABSTRACT
We report the case of a recurrent right pneumothorax, revealing metastasis of an osteosarcoma, 40 months after complete remission. Seven years after surgical excision, the patient is still considered in complete remission. Pneumothorax is rarely the first manifestation of lung metastasis. Osteosarcoma is the most frequent primary tumor. Chest computed tomography detects excavated or subpleural lung metastasis. Differential diagnosis between benign and malignant bullous lesions is important because surgical excision affects survival in some malignancies.
Subject(s)
Femoral Neoplasms/surgery , Lung Neoplasms/secondary , Osteosarcoma/secondary , Pneumothorax/etiology , Adult , Diagnosis, Differential , Femoral Neoplasms/diagnosis , Follow-Up Studies , Humans , Lung Neoplasms/diagnosis , Lung Neoplasms/surgery , Male , Osteosarcoma/diagnosis , Osteosarcoma/surgery , Pneumothorax/surgery , Recurrence , Tomography, X-Ray ComputedABSTRACT
We report a case of idiopathic aneurysm of the azygos vein associated with lung cancer. This abnormality is exceptional because we could find only 8 previous published cases. Computed tomographic scan and especially transesophageal echography were of major importance in identifying the vascular nature of the radiographic abnormality and thus excluding extension of lung cancer.
Subject(s)
Aneurysm/diagnostic imaging , Azygos Vein/diagnostic imaging , Echocardiography, Transesophageal , Aged , Carcinoma, Squamous Cell/diagnosis , Diagnosis, Differential , Hematoma/diagnosis , Humans , Lung Neoplasms/diagnosis , Male , Muscular Diseases/diagnosis , Pectoralis MusclesABSTRACT
Matrix metalloproteinases are particularly potent in degrading basement membrane collagen and other extracellular matrix components. We have investigated the effects of a selective phosphodiesterase 4 inhibitor, RP 73-401 [N-(3, 5-dichloropyrid-4-yl)-3-cyclopentyloxy-4-methoxybenzamide], on gelatinase (matrix metalloproteinase-2 and matrix metalloproteinase-9) activity in ovalbumin-sensitized and -challenged mice. Twenty-four hours after the last challenge, matrix metalloproteinase activity was evaluated in the bronchoalveolar lavage fluids by a zymography technique, and a significant increase in matrix metalloproteinase-9, but not matrix metalloproteinase-2, activity was noted. When administered orally (0.3-3 mg/kg) 1 h before each ovalbumin challenge, the selective phosphodiesterase 4 inhibitor, RP 73-401, significantly reduced this increased matrix metalloproteinase-9 activity in bronchoalveolar lavage fluids. Our data suggest that RP 73-401 may modulate tissue remodelling associated with lung inflammatory processes including asthma.
Subject(s)
3',5'-Cyclic-AMP Phosphodiesterases/antagonists & inhibitors , Benzamides/pharmacology , Bronchoalveolar Lavage Fluid , Matrix Metalloproteinase 9/drug effects , Phosphodiesterase Inhibitors/pharmacology , Pyridines/pharmacology , 3',5'-Cyclic-AMP Phosphodiesterases/metabolism , Animals , Cyclic Nucleotide Phosphodiesterases, Type 4 , Male , Matrix Metalloproteinase 2/drug effects , Matrix Metalloproteinase 2/metabolism , Matrix Metalloproteinase 9/metabolism , Mice , Mice, Inbred BALB CABSTRACT
We report a method designed to improve the specificity of tumour uptake after intravenous injection of an anti-tumour monoclonal antibody (MAb). It consists in increasing the blood clearance of the MAb injected in order to diminish its tissue activity, without altering tumour binding. Po66, an MAb directed against lung squamous cell carcinoma, was radiolabelled with 125I and injected i.v. into tumour-bearing nude mice. Radioactivity uptake by the tumour reached a plateau on days 3-5 which persisted up to day 14 after antibody injection. The radiolabelled Po66 remaining in the circulation on day 5 after injection was removed by means of exsanguination and blood transfusion. This blood exchange technique depleted circulating radiolabelled MAb by 60%, whenever mice had been injected with Po66 or an unrelated control IgG1. The proportion of radiolabelled Po66 taken up by the tumour 5 days after blood exchange did not differ substantially from that of non-exsanguinated controls (96.1% of controls). In contrast, there was a significant decrease in blood radioactivity (46% of control values on day 5). Blood exchange provoked a 1.8 fold increase in the tumour/blood and a 1.5-1.8 fold increase of the tumour/organ radioactivity ratios. After injection of unrelated radiolabelled IgG1, blood exchange reduced by 50% both blood and tumour radioactivity, and did not increase the tumour/blood or tumour/organ ratios. Hence, removal of 60% of circulating Po66, 5 days after its injection, did not affect the binding or retention of the antibody by the tumour, but would probably constitute a marked improvement if the antibody is used for two-phase radioimmunotherapy.