Fig. 1.

Relationship between the titre of allergen-specific IgE and asthma. Serum obtained from children with asthma (open circles) and without asthma (closed circles) attending the urban affluent, urban poor or suburban/rural schools were assayed for specific IgE to mite (a), cockroach (b) or Ascaris (c). The limit of detection for IgE antibodies, represented by the dashed line across the graph, is 0.35 IU/mL. Horizontal lines for each condition indicate the geometric mean of the positive results and values in parenthesis represent the number of samples with negative results. Statistical significance was assessed by a Mann–Whitney U-test.