The efficiency of sputum cell counts in cystic fibrosis.

BACKGROUND: Technical factors relating to processing viscid sputum in cystic fibrosis (CF) and their influence on the reproducibility and validity of cell counts need to be evaluated. In addition, the methods need to be standardized so that they can be applied clinically and in research. OBJECTIVE: To examine the efficiency, reliability and validity of processing small volumes of spontaneously expectorated sputum from subjects with CF. METHODS: Sputum was collected from adults with CF (n=35) and compared with sputum from adults with infective bronchitis or bronchiectasis (IB/B) (n=16), or with asthma or chronic obstructive pulmonary disease (AS/COPD) (n=25). Selected sputum (100 mg to 200 mg) was processed with dithiothreitol (0.1%) and filtered. Total cell count (TCC) and viability were obtained in a counting chamber and cytospins were prepared and stained with Wright's for a differential cell count. Sputum and filter remnant were processed for TCC, viability and differential cell count, and the efficiency was determined by comparing the mean loss in cell yield to the filter. Two different portions from the same sputum sample were processed for cell counts to determine reproducibility. Results were compared with those from IB/B and AS/COPD groups. RESULTS: Efficiency of cell dispersal was excellent and similar to that in AS/COPD and IB/B groups. Reproducibility of cell counts from two portions of a sputum sample was high (>or=0.80). CF sputum demonstrated a raised TCC and neutrophilia similar to IB/B but significantly higher than AS/COPD. CONCLUSION: The selection method of evaluating cell counts in viscid CF sputum is efficient, reproducible and valid.

Uptake of 18fluorodeoxyglucose in the cystic fibrosis lung: a measure of lung inflammation?

Positron emission tomography is a three-dimensional imaging technique that measures physiological effects, including metabolism. 18Fluorodeoxyglucose has been extensively used as a tracer of cellular energy metabolism in the brain and in tumour detection. As neutrophils utilise glucose as an energy source during their respiratory burst, it was hypothesised that 18fluorodeoxyglucose uptake, by these cells, could be interpreted as a measure of neutrophil activation in cystic fibrosis (CF). Ten adult CF patients were given a bolus intravenous injection of 18fluorodeoxyglucose, followed by a 90-min dynamic mid-lung acquisition scan. Right-lung 18fluorodeoxyglucose uptake was assessed using a Patlak plot and values were converted to glucose utilisation. Three clinically inactive pulmonary sarcoidosis patients served as controls. From the 10 CF patients with baseline sputum neutrophils of 14 x 10(6) cells x mL(-1) who were investigated, seven were found to have sputum at a normal or slightly depressed glucose utilisation rate (mean 1.33 micromol x g(-1) x h(-1)) compared with a mean of 2.82 micromol x g(-1) x h(-1) for the sarcoidosis patients. In eight patients, receiving inhaled tobramycin therapy, no change in lung glucose utilisation or sputum neutrophil counts were found. Despite high-sputum neutrophil levels, lung glucose utilisation was not elevated in patients with cystic fibrosis.

Changes in the cellular profile of induced sputum after allergen-induced asthmatic responses.

Allergen inhalation causes airway inflammation and an increase in histamine airway responsiveness. We have used cell counts in sputum induced by hypertonic saline aerosol to assess airway inflammation before and 32 h after asthmatic responses to allergen. Twelve asthmatic subjects (mean age, 27.4 yr; range, 20-38 yr) had an inhalation test with D. farinae, ragweed pollen, or cat extract. All of them developed an early response with a fall in FEV1, of 24.8% (SD, 6.3%); nine of 12 had a definite late response (fall in FEV1 greater than or equal to 15%), and 10 of 12 had an increase in airway responsiveness to histamine at 32 h (PC20 reduced by greater than twofold). Sputum was induced by hypertonic saline after the histamine test, before and 32 h after the allergen challenge, at the same time of day. The quality of the sample was scored according to visual inspection and inverted microscopy and by salivary contamination. Plugs arising from the lower respiratory tract were selected for further evaluation. Differential cell counts of eosinophils (Eo) and metachromatic cells (MCC) (mast cell and basophils) were obtained from direct smears, blind to the clinical procedures. The mean fall in FEV1 after hypertonic saline was 6.4% (range, zero to 28%). The sputum samples were adequate in 79.5% of attempts. Eo and MCC increased significantly from 3.8 (4.4) to 18.2 (22.8)% (p = 0.01) and from 0.05 (0.17) to 0.25 (0.76)% (p = 0.04), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)