Allergy Panel 11, Mold Group

Alternaria alternata is one of the most clinically important allergenic moulds, ubiquitous both outdoors (on decaying vegetation) and indoors where moisture is present. Its major allergen Alt a 1 is a unique fungal protein that drives IgE-mediated sensitisation in atopic individuals. Exposure occurs primarily via inhalation of airborne spores, which peak in warm, dry weather and can trigger immediate hypersensitivity reactions in sensitised patients.

Alternaria sensitisation is strongly associated with allergic rhinitis and asthma; it is an independent risk factor for asthma severity and has been linked to life-threatening exacerbations. Detection of specific IgE confirms sensitisation and supports clinical correlation with exposure history and symptoms. The degree of sensitisation (class grade) provides some indication of reactivity, though clinical response is not strictly dose-dependent.

Aspergillus fumigatus is a thermotolerant saprophytic mould found in soil, compost, and indoor environments. Its spores are small enough to reach the lower airways, where they can provoke IgE-mediated allergy, colonise damaged airways, or trigger allergic bronchopulmonary aspergillosis (ABPA) in susceptible hosts. IgE directed against Asp f allergens reflects Type I sensitisation.

Aspergillus-specific IgE is central to the diagnosis of ABPA, where elevated total IgE and Aspergillus-specific IgE occur alongside asthma and radiological findings. Isolated sensitisation without ABPA can contribute to allergic rhinitis, asthma exacerbations, and occupational allergy. The result must be interpreted with total IgE, eosinophil count, imaging, and lung function.

Cladosporium species are among the most abundant airborne moulds worldwide, thriving both outdoors on plant material and indoors in damp environments. Cladosporium herbarum produces a range of allergenic proteins; spore counts peak in late summer and autumn. IgE sensitisation develops in genetically susceptible individuals following repeated inhalation.

Cladosporium is a common trigger of seasonal allergic rhinitis and can exacerbate asthma. Cross-reactivity with other fungi is limited, so specific IgE helps pinpoint the relevant allergen in polysensitised patients. Clinical relevance is confirmed by symptom timing aligned with outdoor spore seasons or indoor mould exposure.

Penicillium chrysogenum (formerly Penicillium notatum) is a cosmopolitan mould found on decaying food, damp walls, and in poorly ventilated indoor spaces. Its spores are readily aerosolised and inhaled. The genus produces multiple allergens, some shared across Penicillium species, that elicit IgE responses in atopic individuals.

Penicillium sensitisation contributes to perennial allergic rhinitis, asthma, and exacerbations in damp indoor environments. It is less strongly associated with severe asthma than Alternaria or Aspergillus but remains clinically relevant in patients with mould-rich exposures. Specific IgE confirms sensitisation and guides environmental control measures.

Candida albicans is a commensal yeast of human mucosa (gut, oropharynx, vagina) and a facultative pathogen. Unlike environmental moulds, exposure is primarily endogenous. IgE to Candida allergens can develop in atopic individuals, though its clinical relevance in respiratory allergy is less clear than for dermatological or mucosal disease. Cross-reactivity with other fungi has been described.

Candida-specific IgE is occasionally positive in polysensitised atopic patients but does not typically drive isolated respiratory allergy. Elevated IgE may correlate with chronic mucocutaneous candidiasis or atopic dermatitis in some patients. Interpretation requires clinical context; many positive results reflect cross-reactivity or asymptomatic sensitisation rather than causative allergy.

Fusarium species are soilborne moulds and plant pathogens, also found indoors in water-damaged buildings and on shower curtains. Fusarium proliferatum is a representative allergen source within the genus. Spores become airborne and can be inhaled; allergen proteins provoke IgE production in susceptible individuals.

Fusarium sensitisation is less prevalent than Alternaria or Cladosporium but is relevant in patients with water-damage exposure or occupational agricultural contact. Specific IgE supports the diagnosis of mould-induced allergic rhinitis or asthma when symptoms correlate with exposure. Clinical significance increases when multiple mould IgE are elevated.