Background: Blomia tropicalis sensitization is associated with asthma in different tropical and sub-tropical countries; however, information about the specific molecular components associated with this disease is scarce.
Objective: Using molecular diagnosis, we sought to identify B. tropicalis allergens associated with asthma in Colombia.
Methods: Specific IgE (sIgE) to eight B. tropicalis recombinant allergens (Blo t 2/5/7/8/10/12/13 and 21) was determined using an in-house developed ELISA system in asthmatic patients (n=272) and control subjects (n=298) recruited in a national prevalencestudy performed in Colombian cities (Barranquilla, Bogotá, Medellín, Cali and San Andrés). Sample study included children and adults (mean age: 28±SD 17 years old). Cross-reactivity between Blot 5 and Blo t 21 was evaluated by ELISA-inhibition.
Results: Sensitization to Blo t 21 (aOR: 1.9; 95% CI: 1.2 – 2.9) and Blo t 5 (aOR: 1.6; 95%CI: 1.1 – 2.5), but not Blo t 2, was associated with asthma. sIgE levels to Blo t 21 and to Blo t 5 were significantly higher in the disease group. Cross-reactivity between Blo t 21 and Blo t 5 is on average moderate; however, individual analysis indicates that may be high (>50%) in some cases.
Conclusions: Although Blo t 5 and Blo t 21 has been described as common sensitizers, this is the first report of their association with asthma. Both components should be included in molecular panels for allergy diagnosis in the tropics.

Key words: Asthma, Molecular diagnosis, Component-resolved diagnostics, Allergy, Blomia tropicalis, IgE, Recombinant allergens, Multiplex platform, House dust mites, Case-control study, Precision medicine