Perfil de proteínas antigênicas derivadas do extrato total de polens de lolium multiflorum e de sua fração reconhecidas por anticorpos das classes ige e igg4 de pacientes atópicos com potencial diagnóstico e terapêutico

Abstract

Lolium multiflorum (Lm) has been an important source for sensitizing individuals in the southern region of Brazil but despite its importance, there is no information in the literature that characterizes its allergens, making it difficult for specific diagnosis and treatment of patients. The aim was to characterize novel immunodominant antigens derived from Lm total extract (S1) and a fraction isolated (S2) in this study with potential application for allergy diagnosis by evaluating the frequency of IgE and IgG4 reactivity. An ion-exchange chromatography protocol was used to isolate -expansins from the S1 and the eluted aliquot was named S2. After that, both extracts were submitted to SDS-PAGE to obtain the electrophoretic profile. For evaluating the reactivity of specific antibodies, 46 atopic (AT) patients and 16 non–atopic (NAT) individuals were selected. The levels of specific IgE and IgG4 antibodies against S1 or S2 were determined by ELISA and Immunoblotting. The electrophoretic profile of S1 total extract showed more intensity with 12, 32, and 58 kDa bands while the 32 kDa was the main component in the S2 fraction. Specific IgE antibody levels measured by ELISA were significantly greater in AT compared to NAT subjects, using either S1 extract or S2 fraction, showing a similar degree of IgE reactivity in all individuals when using S1 or S2 in the coating phase. Specific IgG4 antibody levels measured by ELISA were significantly greater in AT compared to NAT subjects, using either S1 extract or S2 fraction, showing a similar degree of IgG4 reactivity in all individuals when using S1 or S2 in the coating phase. Thus, this study demonstrated that S2 is as effective as S1 allergen extract for diagnosing atopic individuals, particularly, the 32 kDa band was the most immunodominant component and it may be a major allergen in triggering the allergic response induced by Lm. The frequency of serum reactivity from AT patients against S1 and S2 extracts determined that the 32 kDa band was the component with the highest reactivity in both extracts, recognized by 100% of the serum pools of AT patients. Thus, this study demonstrated that the S2 fraction is as effective as the S1 allergenic extract for the diagnosis of atopic individuals, especially the 32 kDa band that was the most immunodominant component and could therefore be the main allergen in triggering the allergic response induced by Lm. In addition, IgG4 results are also promising and further studies are needed to be performed to better understand whether S2 may be useful in specific immunotherapy.