For a balanced clinical interpretation of an allergological test result it is of great importance to distinguish between genuine sensitization and cross-reactivity. In pollen-allergic patients, who have, for example, a serological and/or skin reactivity to different allergens, it is important to distinguish between genuine sensitization and cross-reactivity. In pollen-allergic patients with serological and/or skin reactivity to different pollen species (e.g. grasses, birch, mugwort) this constellation may indicate either genuine sensitization or cross-reactivity to so-called cross-reactive panallergens. Such panallergens are for example: profilins (e.g. Bet v 2, Phl p 12, Amb a 8 and others), polcalcins (e.g. Bet v 4, Phl p 12 and others) storage proteins (e.g. Cor a 9, Jug r 1, Ana o 1, Pis v 1 and others) or lipid transfer proteins (e.g. Pru p 3, Cor a 8 and others).
The differentiation between genuine sensitization and cross-reactivity is only possible if the detection of IgE-reactivity to specific marker allergens (main allergens) is successful. Only then is a genuine primary sensitization present. Such a differentiation allows a differentiated verodnugation behaviour during allergen-specific immunotherapy (see SCIT below).