Molecular IgE sensitization profiles of urban and rural children in South Africa

Abstract

Background Allergens can act as disease‐triggering factors in atopic dermatitis (AD) patients. The aim of the study was to elucidate the molecular IgE sensitization profile in children with and without AD living in urban and rural areas of South Africa. Methods Specific IgE reactivity was assessed in 166 Black South African children aged 9‐38 months using a comprehensive panel of microarrayed allergens. According to clinical characterization children fell in four groups, urban AD cases (n = 32), urban controls (non‐AD, n = 40), rural cases (n = 49) and rural controls (non‐AD, n = 45). Results IgE reactivity to at least one of the allergens was detected in 94% of urban and 86% of rural AD children. House dust mite (HDM; 81% urban, 74% rural AD) and animal‐derived allergens (50% urban, 31% rural AD) were the most frequently recognized respiratory allergens, whereas IgE to pollen allergens was almost absent. Urban AD children showed significantly higher frequency of IgE reactivity (50%) to mouse lipocalin, Mus m 1, than rural AD children (12%). The most frequently recognized food allergens were from egg (63% urban, 43% rural AD), peanut (31% vs 41%), and soybean (22% vs 27%), whereas milk sensitization was rare. α‐gal‐specific IgE almost exclusively occurred in rural children (AD: 14%, non‐AD: 49%). Conclusion Molecular allergy diagnosis detects frequent IgE sensitization to HDM, animal but not pollen allergens and to egg, peanut, and soy, but not milk allergens in African AD children. Urban AD children reacted more often to Mus m 1, whereas α‐gal sensitization is more common in rural children likely due to parasite exposure.

The Meat of the Matter: Understanding and Managing Alpha-Gal Syndrome

“…Studies from Germany, Italy, South Africa, Kenya, Ecuador, and the United States have demonstrated higher rates of sensitization to alpha-gal in those living in rural versus urban areas. 3,15,45,[49][50][51] The alpha-gal sensitization rates among rural children in lower-and middle-income countries may be due to increased exposures to alpha-gal-containing endo-and ectoparasites. 15,43 In the southeastern United States, initial sensitization rates ranged from 15% to 25% based on cohorts of approximately 50-250 patients.…”

Editorial comments on: “Der p 23‐specific IgE response throughout childhood and its association with allergic disease: A birth cohort study”

“…The relationship between IgE to other specific house dust mite molecules and asthma, allergic rhinitis, and atopic dermatitis in the same subjects can shed light on the relative importance of Der p 23 compared with the other allergen molecules, the patterns of sensitization, and the roles of each molecule in this process. For instance, Der p 1, Der p 2, and Der p 23 from the so-called group A seemed to be initiators with IgE responses progressing to other allergens designated groups B and C. 4 In the same study, early (<5 years) onset of sensitization to house dust mite was associated with broader polysensitization, which in turn was associated with a higher risk of mite-related allergic rhinitis and asthma. Sensitization to house dust mite is common worldwide 3 ; thus, these data can potentially be useful to support clinical decision-making more broadly.…”

From Allergen Molecules to Molecular Immunotherapy of Nut Allergy: A Hard Nut to Crack

“…Table 1 provides an overview of nut allergy prevalence studies, in particular from Europe, Northern America, Asia, Australia and Africa ( 38 , 48 – 50 , 52 – 84 ).…”

“…Peanut allergens are the most frequently recognized nut allergens in South Africa ( 84 ) as determined in allergic children whereas IgE recognition of peanut allergens seems to be often asymptomatic as reported for Zimbabwe ( 52 ) but data regarding the prevalence of nut allergies in Africa are rare.…”