In:
The Journal of Immunology, The American Association of Immunologists, Vol. 161, No. 12 ( 1998-12-15), p. 7031-7039
Abstract:
Serum IgE was used to isolate a cDNA coding for a 9.4-kDa two EF-hand calcium-binding allergen, Aln g 4, from a λgt11 expression cDNA library constructed from alder (Alnus glutinosa) pollen. rAln g 4 was overexpressed in Escherichia coliand purified to homogeneity. It reacted with serum IgE from 18% of pollen-allergic patients (n = 122); shared IgE epitopes with homologous allergens present in tree, grass, and weed pollens; and thus belongs to a family of highly cross-reactive pollen allergens. Exposure of two E. coli-expressed rAln g 4 fragments comprising amino acids 1–41 and 42–85 to patients’ IgE Abs, as well as to a rabbit antiserum raised against purified rAln g 4, indicated that most of the B cell epitopes reside in the N-terminal portion of the protein. IgE recognition of Aln g 4 was strongly modulated by the presence or absence of calcium. Circular dichroism analysis of rAln g 4 revealed that the protein consisted mostly of α helical secondary structure and possessed a remarkable thermal stability and refolding capacity, a property that was greatly reduced after calcium depletion. Circular dichroism analysis of the calcium-bound and apo form of rAln g 4 indicated that calcium-induced modulation of IgE binding could be due to changes in the protein conformation. Purified rAln g 4 elicited dose-dependent basophil histamine release and immediate type skin reactions in sensitized patients. It may hence be useful for allergy diagnosis and for specific immunotherapy.
Type of Medium:
Online Resource
ISSN:
0022-1767
,
1550-6606
DOI:
10.4049/jimmunol.161.12.7031
Language:
English
Publisher:
The American Association of Immunologists
Publication Date:
1998
detail.hit.zdb_id:
1475085-5