Expression of the American cockroach Per a 1 allergen in mammalian cells.
BACKGROUND
Cockroach allergens are one of the major etiologic risk factors for developing IgE-mediated allergic respiratory illness throughout the world. Per a 1 is a cross-reactive allergen of American and German cockroaches. This study aimed to investigate the expression of a recombinant American cockroach (Periplaneta americana) Per a 1, C42, allergen in mammalian COS-1 cells.


METHODS
The COS-1 cells and Escherichia coli were used to express the P. americana C42 allergen. Recombinant proteins were purified with hydroxylapatite and DE52 chromatography. Biologic reactivities of recombinant proteins were examined by direct IgE binding and IgE inhibition studies with the enzyme-linked immunosorbent assay (ELISA).


RESULTS
C42 was successfully expressed in the mammalian COS-1 cell as a 50-kDa secreted protein, and purified from the culture medium. The specific human IgE antibodies against recombinant C42 from either E. coli (C42-E. coli) or COS-1 (C42-COS-1) were compared by ELISA with 12 sera from Per a 1 and C42 skin-test-positive patients. All atopic sera contained specific IgE antibodies to C42 from either E. coli or COS-1. Moreover, recombinant C42-COS-1 bound higher levels of serum IgE than recombinant C42-E. coli among C42-sensitive atopic patients, and a statistically significant difference (P<0.01) was found between them. In addition, recombinant C42-COS-1 as an inhibitor revealed higher inhibition of IgE binding to natural Per a 1 than recombinant C42-E. coli.


CONCLUSIONS
The biologically highly reactive recombinant C42 produced in the COS-1 cell provides an alternative expression system and will facilitate studies on the immune response of asthma patients to cockroach allergens.
Wu
C H
CH
Department of Education and Research, Taichung Veterans General Hospital, Taiwan, Republic of China.
Lee
M F
MF
Wang
N M
NM
D000485:Allergens / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D000818:Animals; D052179:Antigens, Plant; D019556:COS Cells; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D007073:Immunoglobulin E / Q000276:immunology; D010526:Periplaneta / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism; D014162:Transfection
D000485:Allergens; D052179:Antigens, Plant; D011994:Recombinant Proteins; C091463:allergen Per a I; D007073:Immunoglobulin E