Reference values of total serum IgE and their significance in the diagnosis of allergy among the young adult Kuwaiti population.

BACKGROUND: The reference total serum immunoglobulin (IgE) values and the usefulness of total IgE values in the diagnosis of allergy have not been established for the Kuwaiti population. The literature reference values may not be applicable since such values often vary among ethnic nationalities. OBJECTIVE: The aim of this study was to establish the reference IgE values for the young adult Kuwaiti population and to determine the usefulness of such values in the diagnosis of allergic diseases in the community. METHODS: A total of 1057 randomly selected young adults were screened for atopy using the Pharmacia CAP-PhadiatopR method. Atopy was detected in 423 individuals (40.0%). Total serum IgE was then measured in 542 randomly selected Phadiatop-negative (non-atopic) cases in the age range 18-50 years (mean 28.9 years) and male:female ratio of 1.3. RESULTS: Serum total IgE values in non-atopics covered a very wide range (< 2-1993 kU/L) with a geometric mean (GM) value of 43.7 kU/L. The reference range, calculated as the 95% confidence interval of the log IgE (95% CI) was 3.2-602.5 kU/L. The 90% CI was 11.7-162 kU/L. The GM was significantly higher for males than females, (53.7 vs. 35.5 kU/L, P < 0.001) and for smokers than non-smokers, (64.6 vs. 40.7 kU/L, P < 0.01), but was independent of age. Although the GM for the non-atopics (43.7 kU/L) was significantly lower than those of the asymptomatic atopics (213.8 kU/L) and allergic asthmatics (626.6 kU/L), the 95% CI for the three groups showed considerable overlap. CONCLUSIONS: These results show that the normal total IgE values in the young adult Kuwaiti population are generally high and that the distribution of the values is so wide that the diagnostic value of total serum IgE in this community is likely to be very limited.

High frequency of IgE receptor Fc epsilonRIbeta variant (Leu181/Leu183) in Kuwaiti Arabs and its association with asthma.

The presence of IgE receptor Fc epsilonRIbeta polymorphism (181/183) was investigated in Kuwaiti asthmatic patients and controls using an allele refractory mutation screening (ARMS) test. The variant sequence (Leu181/Leu183) was detected in 72% (320/442) chromosomes analysed. Homozygous LL genotype was detected in 48% (46/96) asthmatic subjects compared to 31% (39/125) in non-asthmatics. In 11/52 families mothers of the asthmatic children were themselves asthmatic and 3/11 asthmatic mothers had homozygous LL genotype. 80% of the homozygous LL asthmatics showed a positive skin prick test (SPT) compared with 28% of non-asthmatics with the same genotype. In heterozygous NL asthmatics a positive SPT was found in 60% cases compared to 17% in non asthmatics with the same genotype. The incidence of hay fever (HF) and eczema (E) was also found to be higher in homozygous LL asthmatics compared with the non-asthmatics with the same genotype. This study reports a high prevalence of IgE receptor Fc epsilonRIbeta variants in Kuwaiti Arabs compared with British, Australian and Austrian populations studied before. The association of Leu181/Leu183 variant with asthma in Kuwaitis underlines its significance as a risk factor in manifesting the clinical phenotype in this population.