Contribution of Ara h 2 to peanut-specific, immunoglobulin E-mediated, cell activation.


Journal Article

BACKGROUND: Ara h 2 is a potent peanut allergen but its contribution to the ability of a crude peanut extract (CPE) to cross-link IgE and activate mast cells has not been rigorously evaluated. OBJECTIVE: To measure the contribution that Ara h 2 makes to the effector function of a CPE. METHODS: Ara h 2 was specifically removed from a CPE as demonstrated by immunoblots, 2D gels, and an inhibitory ELISA. Functional assays of sham-treated and Ara h 2-depleted CPEs were performed with RBL SX-38 cells sensitized with IgE from highly peanut-allergic subjects and with naturally sensitized basophils. RESULTS: Depletion of approximately 99% of the Ara h 2 from the CPE led to an increase in the concentration of the CPE necessary to give 50% of maximal degranulation (EC50) of the SX-38 cells following sensitization with sera that contain anti-Ara h 2 IgE. Assays with a pool of 10 sera showed a small but significant increase in the EC50 following depletion of Ara h 2 (1.65+/-0.15-fold; P<0.05) and assays of seven individual sera showed a similar increase in the average EC50 (1.7+/-0.2-fold; P<0.02). The percent of the anti-peanut IgE that binds Ara h 2 correlated with an increase in the EC50 of the CPE following depletion of Ara h 2 (r=0.83; P<0.02). On the other hand, data from three of these patients studied with a basophil histamine release assay did not show a significant effect of depletion of Ara h 2. CONCLUSION: Based on its ability to cross-link IgE effectively, Ara h 2 is clearly an important peanut allergen. Its ability to cross-link IgE effectively from a specific serum is related to the proportion of anti-Ara h 2 in that serum but Ara h 2 does not account for a majority of the effector activity of the CPE for any of the sera studied.

Full Text

Cited Authors

  • McDermott, RA; Porterfield, HS; El Mezayen, R; Burks, AW; Pons, L; Schlichting, DG; Solomon, B; Redzic, JS; Harbeck, RJ; Duncan, MW; Hansen, KC; Dreskin, SC

Published Date

  • May 2007

Published In

Volume / Issue

  • 37 / 5

Start / End Page

  • 752 - 763

PubMed ID

  • 17456223

Pubmed Central ID

  • 17456223

Electronic International Standard Serial Number (EISSN)

  • 1365-2222

International Standard Serial Number (ISSN)

  • 0954-7894

Digital Object Identifier (DOI)

  • 10.1111/j.1365-2222.2007.02701.x


  • eng