Alérgenos de pólen de Lolium multiflorum (Lam. 1779): determinação da reatividade cruzada de anticorpos IgE aos componentes alergênicos de extratos comerciais de gramíneas

Abstract

Background: Lolium multiflorum (Lm) grass pollen, Poaceae family, is the major cause of pollinosis in South Brazil. There are no studies evaluating the cross-reactivity between allergenic fractions from L. multiflorum and other pollen grass species. Objective: To evaluate the sensitization to Lm pollen allergens in patients with pollinosis through the detection of specific IgE by skin prick test (SPT) and immunoassays (ELISA). To characterize immunodominant fractions from L. multiflorum pollen allergens, and crossreactivity with other allergens from commercial grass pollen extracts. Methods: Thirty eight serum samples from patients with seasonal allergic rhinitis (SAR group), 35 serum samples from patients with perennial allergic rhinitis (PAR group) and 30 serum samples from non atopic patients (NA group) were tested for IgE reactivity. The sensitization was evaluated using SPT and IgE specific levels against L. multiflorum pollen extract were determined by ELISA. Inhibition ELISA and Immunoblotting were used to evaluate the cross-reactivity between allergens from L. multiflorum and commercial grass pollen extracts. Results: Serum specific IgE antibodies against Lm were detected in 100% of patients from SAR group and in 8.6% of patients from PAR group. Inhibitions observed in specific IgE ELISA demonstrated Lm cross-reactivity between homologous (Lm) and heterologous (L. perenne [Lp] or Gramíneas II [GII]) grass pollen extracts, but not for Gramíneas I (GI). Fourteen IgE binding fractions were observed and the fractions of 26, 28 and 32 kDa were the most frequent (> 90%). For IgE Immunoblotting inhibition Lm, Lp and GII inhibited significantly IgE binding to the most Immunodominant fractions of Lm, particularly the 55kDa fraction. The 26 kDa fraction were not inhibited by the Lp extract, but it was inhibited by Lm and, GII in lower proportion. Conclusion: Lm pollen extract is more appropriate instead of other phylogenetic related grass pollens for determining quantitative sensitization in diagnostic and therapeutic purposes to pollinosis due to L. multiflorum pollen.