BACKGROUND: Sputum induction is a tool recommended for the assessment of airway inflammation and disease management. Currently, its use is limited because samples need to be processed within 3 h of induction (ie, while cells are viable); therefore, this procedure is unavailable to most clinicians. OBJECTIVE: To develop a fixation method for induced sputum samples that allows for a delay in processing while maintaining sample integrity and not altering the standard processing method. METHODS: Sputum samples were collected and split into three portions: a fresh sample processed using the routine method (within 3 h, using dithiothreitol); fixation in alcohol followed by delayed processing using the routine method (within 48 h to 72 h, using dithiothreitol); and fixation in formaldehyde followed by delayed processing using an alternative method (within 48 h to 72 h, using proteolysis). For each method, cytospins were prepared and differential cell counts were performed. RESULTS: Fixation in alcohol provides accurate measures of eosinophils and macrophages, but not neutrophils. Formaldehyde fixation provides accurate measures of neutrophils and macrophages, but not eosinophils. DISCUSSION: Alcohol fixation is a superior method for eosinophil quantification. It requires alteration of standardized methods for sputum sample processing and should be recommended for monitoring eosinophilic airway disease in settings where immediate processing of a sputum sample is not possible.
BACKGROUND: Sputum induction is a tool recommended for the assessment of airway inflammation and disease management. Currently, its use is limited because samples need to be processed within 3 h of induction (ie, while cells are viable); therefore, this procedure is unavailable to most clinicians. OBJECTIVE: To develop a fixation method for induced sputum samples that allows for a delay in processing while maintaining sample integrity and not altering the standard processing method. METHODS: Sputum samples were collected and split into three portions: a fresh sample processed using the routine method (within 3 h, using dithiothreitol); fixation in alcohol followed by delayed processing using the routine method (within 48 h to 72 h, using dithiothreitol); and fixation in formaldehyde followed by delayed processing using an alternative method (within 48 h to 72 h, using proteolysis). For each method, cytospins were prepared and differential cell counts were performed. RESULTS: Fixation in alcohol provides accurate measures of eosinophils and macrophages, but not neutrophils. Formaldehyde fixation provides accurate measures of neutrophils and macrophages, but not eosinophils. DISCUSSION: Alcohol fixation is a superior method for eosinophil quantification. It requires alteration of standardized methods for sputum sample processing and should be recommended for monitoring eosinophilic airway disease in settings where immediate processing of a sputum sample is not possible.
Authors: Ruth H Green; Christopher E Brightling; Susan McKenna; Beverley Hargadon; Debbie Parker; Peter Bradding; Andrew J Wardlaw; Ian D Pavord Journal: Lancet Date: 2002-11-30 Impact factor: 79.321
Authors: E Pizzichini; M M Pizzichini; A Efthimiadis; S Evans; M M Morris; D Squillace; G J Gleich; J Dolovich; F E Hargreave Journal: Am J Respir Crit Care Med Date: 1996-08 Impact factor: 21.405
Authors: M M Pizzichini; E Pizzichini; A Efthimiadis; A J Chauhan; S L Johnston; P Hussack; J Mahony; J Dolovich; F E Hargreave Journal: Am J Respir Crit Care Med Date: 1998-10 Impact factor: 21.405