Serum total IgE and specific IgE to Dermatophagoides pteronyssinus, but not eosinophil cationic protein, are more likely to be elevated in elderly asthmatic patients
Serum IgE (total and five specific) and eosinophil cationic protein (ECP) levels were compared in elderly physician-diagnosed patients with asthma with non-asthmatic controls matched by age and gender to ascertain whether elevated levels are indicators of asthma in the elderly. All subjects and controls were non-smokers. The subjects were participants in the Florida Geriatric Research Program (FGRP), a longitudinal aging study that tracks the health status of people 65 years and older. Frozen sera from 33 randomly selected asthmatic patients and 21 controls, none of whom had any other chronic respiratory disease, such as chronic obstructive pulmonary disease (COPD), all between the ages of 65 and 90, were assessed for total IgE; five specific IgE concentrations (for cat, ragweed, German cockroach, Dermatophagoides pteronyssinus (Dp) and live oak); and ECP levels using the Pharmacia Unicap System. The odds of an elderly asthmatic patient having a total IgE of > 100 KU/L were higher than that for a non-asthmatic patient (odds ratio (OR) = 13.0; Mantel-Haenszel (MH) p = 0.005). The odds of elderly asthmatic patients having at least one positive serum specific IgE compared to elderly age-matched non-asthmatic patients were higher (OR = 21.2; MH p = 0.001). Among the five specific IgE concentrations, only IgE for Dp was higher in asthmatic than in non-asthmatic patients (OR = 13.00; MH p = 0.005). The ECP level was not significantly different between elderly asthmatic and non-asthmatic patients (asthmatic mean = 20.7 microg/L, SE = 0.48; control mean = 19.5 microg/L. SE = 0.76) (mean for younger adults 4.4 microg/L, Pharmacia Diagnostics). The serum of elderly asthmatic patients is more likely to have elevated total IgE and a positive specific IgE to Dp. ECP is elevated in elderly subjects but is not an indicator of asthma.