- Cai Y,
- Carty K,
- Henry RL,
- Gibson PG
Purpose of the Study
To describe induced sputum cell counts in healthy nonasthmatic children, and to compare these with asthmatic children whose asthma was controlled to varying degrees.
Seventy-two children, ages 8 to 14 years, who were regarded as normal controls and 42 children, ages 6 to 18 years, who were known asthmatics. The 72 normal children were identified via a meticulous screening process. Of the 72 normals, 32 were considered to be atopic on the basis of a positive skin test to one or more common inhalant allergens. The remainder were nonatopic. When considering the 42 asthmatic children, 41 were on inhaled corticosteroids. Their asthma control was categorized as satisfactory (15), symptomatic (16), and asthmatic exacerbations (11).
With appropriate safety measures in place, sputum production was induced in all subjects using inhaled hypertonic saline. If significant drops in forced expiratory volume in one second (FEV1) took place, reversal was accomplished with inhaled salbutamol. Sputum samples were analyzed for eosinophils, mast cells, neutrophils, and epithelial cells.
In the nonatopic, normal children, the total cell counts were surprisingly higher than the nonasthmatic atopic children, although this latter group did have significantly more eosinophils. In the asthmatic group, eosinophils and epithelial cell numbers were significantly higher than the normals, and this was true regardless of the degree of control. Generally, however, the better the control the fewer eosinophils and epithelial cells noted.
Markers of airway inflammation, such as eosinophils, were present in the sputum of normal atopic children to a greater degree than the nonatopic normals, perhaps indicating that given an appropriate insult, wheezing could follow. The same marker of inflammation, the eosinophil, was noted in all asthmatics along with significant epithelial cell shedding. These findings transcended all degrees of control.
The data tend to support the notion that we appear to be making some positive strides with modern pharmacotherapeutic agents in controlling the overt symptoms of asthma, but we still have a ways to go in finally containing the demon of inflammation. In addition, with statistically increased markers of inflammation, as noted in the sputum of normal atopic children, what threshold needs to be crossed before clinically apparent asthma develops? Hypertonic saline inhalations as a sputum generating agent is most certainly safe and effective. With adequate sputum for analysis, we may be better able to follow and evaluate the atopic and/or asthmatic child in the real world of first-class allergy management.