Total serum IgE and IgG4 levels in allergic and non-allergic West Indian medical students - abstract

ABSTRACT

Despite high prevalence rates of allergic illnesses in the region, the laboratory indices of these disorders have not been documented. This prospective controlled study was undertaken to determine the levels of sensitizing antibodies (IgE and IgG4) and their variation over a one-year period. The subjects, 17 allergic and 7 non-allergic pre-clinical medical students and laboratory technologists, were selected by questionnaire. Blood samples were collected at approximately 3-monthly intervals and a stool sample at the beginning of the study. Routine haematological and microbiological investigations were carried out on blood and stool samples respectively. IgE was measured by enzyme immunoassay and IgG4 by radial immunodiffusion. Haematological and coprological investigations were normal in all subjects. Total serum IgE levels were higher in allergic subjects than in controls (geometric means 192ñ4.5 and 77ñ3.5 Ku/1 respectively) and there were no seasonal fluctuations in either group. Both groups had similar IgG4 levels which also showed no seasonal variation (geometric means 0.88ñ2.18 and 1.01ñ1.89g/L respectively). These IgG4 values were elevated in comparison with those reported for Europeans (mean 0.6g/1). The total IgE levels in our study, which were within the normal range for temperate populations, were much lower than those reported for tropical populations. Total serum IgE levels in isolation were unable to distinguish between allergic and non-allergic individuals. There was no evidence of a seasonal allergen. The elevation in IgG4 levels in control and allergic subjects has not been previously reported. Chronic antigenic stimulation is thought to produce elevated IgG4 levels. It is possible that chronic perennial allergenic stimulation may contribute to the raised IgG4 levels found in this study (AU)