Imidacloprid inhibits IgE-mediated RBL-2H3 cell degranulation and passive cutaneous anaphylaxis

BACKGROUND: Imidacloprid has been commonly used as a pesticide for crop protection and acts as nicotinic acetylcholine receptor agonists. Little information about the relationship between imidacloprid and allergy is available. OBJECTIVE: This study aims to examine the effects of imidacoprid on IgE-mediated mast cell activation. METHODS: The rat basophilic leukemia cell line RBL-2H3 (RBL-2H3 cells) were treated with 10⁻³ – 10⁻¹² mol/L imidacloprid, followed by measuring the mediator production, influx of Ca²⁺ in IgE-activated RBL-2H3 cells, and the possible effects of imidacoprid on anti-dinitrophenyl IgE-induced passive cutaneous anaphylaxis (PCA). RESULTS: It was shown that imidacoprid suppressed the production of histamine, β-hexosaminidase, leukotriene C4, interleukin-6, tumor necrosis factor-α, and Ca²⁺ mobilization in IgE-activated RBL-2H3 cells and decreased vascular extravasation in IgE-induced PCA. CONCLUSION: It is the first time to show that imidacloprid suppressed the activation of RBL-2H3 cells.

Identification of conformational antigenic epitopes and dominant amino acids of buffalo ß-lactoglobulin.

Major allergen ß-lactoglobulin exists in many mammalian types of milk except human breast. Buffalo milk also contains this major allergen but the detailed information on its epitopes is not available. The aim of this work was to map and characterize its conformational antigenic epitopes. Sixty mimotopes of buffalo ß-lactoglobulin were produced by biopanning of phage display peptide library and then 2 mimotopes, specific for sera from rabbit 1 and 2, respectively, were predicted to be conformational epitope candidates by the use of DNAStar and web tool of MIMOX. On the basis of bioinformation analysis, 5 conserved amino acid residues PL-ENK were identified in 2 conformational epitope sequences and 7 conformational epitopes were derived from 2 mimotopes by molecular modeling. The result showed that these conformational epitopes were located in the 2 regions on buffalo ß-lactoglobulin and composed of 5 hydrophilic and 2 hydrophobic amino acids.

Epitope mapping and identification of amino acids critical for rabbits IgG-binding to linear epitopes on buffalo beta-lactoglobulin.

Buffalo milk safety was highlighted with the increase in dietary consumption, and a little information is available on buffalo milk allergy except for cross-reactivity between buffalo and cow milk. In this work, linear epitopes and critical amino acids of buffalo ß-lactoglobulin were defined by 4 rabbit's sera using SPOTTM peptide arrays approach based on the defined mimotopes. The eight epitopes on buffalo ß-lactoglobulin were located in the position of A6(21-30), A7(25-34), A8 (29-38), B4 (73-82), B5(77-86), C(87-96), F4(134-143) and F8(150-159), respectively. Among them, four epitopes (A7, A8, F4 and F8) were described as the most major epitopes and peptide (A6, B4, B5 and C) as the second major epitopes. Following single AA substitutions (Alanine or Glycine) at each position of the major epitopes, 2,3,2,3,5 and 3 of critical amino acids were identified on epitopes of A6, A8, B5, C , F4 and F8, respectively, which vary in distribution among the epitopes, such as in C terminal or N terminal and in continuous or discontinuous forms, characteristics including hydrophobicity, polar and charge, and existed frequency.