Serum total IgE in normal subjects and the influence of a family history of allergy.

The purpose of this study was to establish the range of serum total immunoglobulin E (IgE) in a healthy population free of personal and family history of allergy, and to determine whether a family history of allergy influenced serum IgE levels. Using commercially available Phadebas reagents, the mean serum IgE in eighty-four adults aged 17-30 years with no personal or family history of allergy was found to be 38.8 iu/ml. Seventy-five percent of subjects had a serum IgE below 50 iu/ml and in only one subject was serum IgE in excess of 150 iu/ml, which we suggest be taken as the upper limit of normal. When healthy subjects with no personal history but with a family history of allergy were included with this normal population, the mean serum IgE in 207 subjects was 95.4 iu/ml and the upper limit of the distribution curve over 200 iu/ml, suggesting an influence of genetic factors on IgE production.