Immunologic characterization of natural and recombinant Mal f 1 yeast allergen.
BACKGROUND
Individuals with atopic dermatitis (AD) often have IgE antibodies against protein components of Malassezia furfur. The cDNA encoding one of these proteins (Mal f 1) has recently been cloned and sequenced.


OBJECTIVE
We sought to express recombinant Mal f 1 (rMal f 1) allergen in large quantities by using different expression systems. The primary aim was to characterize the IgE-binding properties of rMal f 1 in comparison with its natural counterpart in M furfur extract.


METHODS
We have expressed and purified Mal f 1 from prokaryotic (Escherichia coli) and eukaryotic cells (baculovirus-infected insect cells). The rMal f 1 produced in both systems has been tested for the ability to be recognized by IgE from patients with specific serum IgE to M furfur by using immunoblotting and the Pharmacia CAP System RAST FEIA.


RESULTS
Sixty-one percent of sera from 95 patients showed positive RAST responses to the rMal f 1 produced in the baculovirus expression system and 43% to the E coli -produced rMal f 1. Both the E coli - and baculovirus-produced proteins can specifically inhibit IgE binding to a 36-kd protein band (Mal f 1) in immunoblotting, indicating that the recombinant proteins contain the majority, if not all, the IgE-binding epitopes of Mal f 1. Recombinant Mal f 1 is able to release histamine from basophils of an atopic individual.


CONCLUSIONS
We have expressed and purified rMal f 1, which can bind IgE in a way resembling natural Mal f 1. The ability to produce recombinant allergens with similar properties to their native counterparts has many potential uses, such as accurately diagnosing causes of IgE-mediated allergy.
D000485:Allergens / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D000917:Antibody Formation; D018076:DNA, Complementary / Q000032:analysis; D003876:Dermatitis, Atopic / Q000097:blood / Q000276:immunology; D005656:Fungal Proteins / Q000276:immunology; D006636:Histamine Release; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D010936:Plant Extracts / Q000276:immunology; D014176:Protein Biosynthesis; D011852:Radioallergosorbent Test; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification