Sensitization to cockroach in Italy: a multicentric study.

The prevalence of sensitization to cockroach (CR) was evaluated by skin prick test (SPT) in 1299 patients consecutively referred for rhinitis and asthma to five allergy centers in northern, central, and southern Italy. In patients with positive SPT to CR, an SPT with D. pteronyssinus extract was made. RAST inhibition was performed with pooled sera of subjects with positive SPT and RAST of at least Class 3 for CR and D. Pteronyssinus, to assess the cross-reactivity between these two allergenic sources. The protein content of allergen extracts was assayed by isoelectric focusing (IEF). A total of 170 patients (13%) had a positive SPT with CR extract, and 133 of them (78.2%) were also positive for D. pteronyssinus. RAST inhibition showed a cross-reactivity between CR and D. pteronyssinus, and IEF detected in the extracts employed a series of bands focusing at the same pI of CR and D. pteronyssinus relevant allergens. Therefore, the prevalence of sensitization to CR in the population studied, corresponding to 13%, suggests that CR extract might be added to standard SPT panels for respiratory allergy. However, the cross-reactivity with D. pteronyssinus calls for careful evaluation of the clinical importance of this sensitization.