LONGITUDINAL OBSERVATIONS OF SERUM IGE AND SKIN PRICK TEST RESPONSE

The objective of the study was to assess skin prick test and IgE chang es in a working population surveyed 5 yr apart and to determine whethe r age and smoking habits modify these changes. SPTs were performed on 223 subjects by the same method and common allergens (a mixture of gra ss pollens and a mixture of 95% house dust and 5% house dust mite). Ig E measurements were done in duplicate by the same technique at each su rvey. A SPT-positive response at the first survey was highly predictiv e of a positive value at the second survey. The prevalence of positive SPT significantly increased in 5 yr (from 17.5 to 24.7%). A strong co rrelation was observed between IgE levels 5 yr apart (r = 0.92), and t he IgE level appeared very stable. The initial IgE level was significa ntly greater among the converters than in consistently negative subjec ts (92.3 versus 30.1 IU/ml). Conversely, the initial IgE level was low er for the reverters than in consistently positive subjects (36.8 vers us 97.0 IU/ml). In SPT negatives, non- and exsmokers had a greater dec rease in IgE than current smokers (p = 0.06). IgE level appears to be a good predictor of SPT changes for both conversion and reversion. The IgE level appears very stable in midadulthood, which suggests that th e adult environment may play a small effect in IgE level.