Resposta imune humoral ao extrato da semente de girassol (Helianthus annuus) em indivíduos atópicos e não atópicos: um estudo piloto

Abstract

Allergic diseases constitute a significant public health problem, significantly impacting the quality of life of a considerable portion of the global population. These diseases are characterized by immediate hypersensitivity reactions following exposure to allergens, whether mediated or not by IgE, with the presence of this immunoglobulin being the defining characteristic of atopy. In the context of allergy, the participation of other antibodies, including IgA and IgG, remains poorly understood. Plant-derived allergens commonly originate from pollen, cereals, and seeds. In this context, sunflower (Helianthus annuus) allergy remains poorly described in Brazil, highlighting the need for investigations into the immunopathology triggered by this allergen. This study aimed to detect and quantify specific IgE, IgA, and total IgG antibodies against crude H. annuus extract. Following approval by the Research Ethics Committee of the Federal University of Uberlândia (CEP/UFU), 78 participants (38 atopic and 40 non-atopic) were recruited at the Hospital de Clínicas-UFU through a direct approach. Blood samples were collected from the participants, processed, separated, and stored. The crude H. annuus extract was obtained by cryomaceration, with protein content determined by the Bradford method and electrophoretic profile analyzed by SDS-PAGE. The quantification of specific serum IgE, IgA, and total IgG antibodies against the H. annuus extract was performed using ELISA, with statistical significance set at p < 0.05. Polypeptide bands ranging from 10 to 250 kDa were observed, with a protein concentration of 13 mg/mL. Comparative analysis revealed a significant difference (p < 0.0001; H = 109.3) among the immunoglobulin classes, with a predominance of IgG reactivity (median 0.6470) compared with the other isotypes. The concentrations of IgE and IgA showed no significant difference (p = 0.2117) and shared the same optical density distribution profile. Furthermore, a moderate positive correlation was observed between serum IgE and IgA levels (rs = 0.489; p = 0.0208), whereas IgG was independent of the other variables. These findings suggest a possible involvement of IgA in the IgE-mediated allergic response in atopic individuals, indicating that IgA may exert a modulatory role in allergic reactions to H. annuus antigens. Additional investigations are necessary to elucidate the immunological mechanisms underlying this association.