Cloning and characterization of profilin (Pru du 4), a cross-reactive almond (Prunus dulcis) allergen.
BACKGROUND
The identity of allergenic almond proteins is incomplete.


OBJECTIVE
Our objective was to characterize patient IgE reactivity to a recombinant and corresponding native almond allergen.


METHODS
An almond cDNA library was screened with sera from patients with allergy for IgE binding proteins. Two reactive clones were sequenced, and 1 was expressed. The expressed recombinant allergen and its native counterpart (purified from unprocessed almond flour) were assayed by 1-dimensional and 2-dimensional gel electrophoresis, dot blot, and ELISA, and screened for cross-reactivity with grass profilin.


RESULTS
The 2 selected clones encoded profilin (designated Pru du 4) sequences that differed by 2 silent mutations. By dot-blot analyses, 6 of 18 patient sera (33%) reacted with the recombinant Pru du 4 protein, and 8 of 18 (44%) reacted with the native form. ELISA results were similar. Almond and ryegrass profilins were mutually inhibitable. Two-dimensional immunoblotting revealed the presence of more than 1 native almond profilin isoform. The strength of reactivity of some patients' serum IgE differed markedly between assays and between native and recombinant profilins.


CONCLUSIONS
Almond nut profilin is an IgE-binding food protein that is cross-reactive with grass pollen profilin and is susceptible to denaturation, resulting in variable reactivity between assay types and between patients.


CONCLUSIONS
Serum IgE of nearly half of the tested patients with almond allergy reacts with almond nut profilin. Because most patients also had pollinosis, the well-known cross-reactivity between pollen and food profilins could account for this pattern of reactivity.
Tawde
Pallavi
P
Department of Biological Science, Florida State University, FL 32306-4370, USA.
Venkatesh
Yeldur P
YP
Wang
Fang
F
Teuber
Suzanne S
SS
Sathe
Shridhar K
SK
Roux
Kenneth H
KH
D000595:Amino Acid Sequence; D052179:Antigens, Plant / Q000235:genetics / Q000276:immunology*; D003001:Cloning, Molecular; D003429:Cross Reactions; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005512:Food Hypersensitivity / Q000276:immunology*; D015723:Gene Library; D006801:Humans; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000276:immunology; D008969:Molecular Sequence Data; D006109:Poaceae / Q000276:immunology; D011058:Pollen / Q000276:immunology; D051304:Profilins / Q000235:genetics / Q000276:immunology*; D027861:Prunus / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology
D052179:Antigens, Plant; D051304:Profilins; D011994:Recombinant Proteins; D007073:Immunoglobulin E