Der p 2 isoallergens have different allergenicity, and quantification with 2-site ELISA using monoclonal antibodies is influenced by the isoallergens.
BACKGROUND
Der p 2 isoallergens have been reported and the possibility of different allergenicity has also been suggested. In addition, the quantification with 2-site ELISA may be affected by the isoallergens.


OBJECTIVE
Two different recombinant Der p 2 (rDer p 2) isoallergens were compared in terms of human IgE responses and the reliability of quantification of them with two-site ELISA kits which use monoclonal antibodies (mAbs) as capture and detection of Der p 2.


METHODS
Seven different Der p 2 cDNA from the cultured Dermatophagoides pteronyssinus (DP) were cloned and polymorphism in nine amino acid residues was found. Two different recombinant isoallergens (rDer p 2A and rDer p 2B) were expressed and compared to their human IgE immune responses by ELISA and the ELISA inhibition test with 23 sera of DP-allergic patients. The reliability of quantification of two different available 2-site ELISA kits, which used mAbs for capture and detection of Der p 2, was evaluated.


RESULTS
The ELISA optical density of rDer p 2B-specific IgE (sIgE) was higher than that of rDer p 2A (P < 0.001). The ELISA inhibition curve of rDer p 2B sIgE in pool I sera (n = 5; high sIgE both to rDer p 2A and rDer p 2B) did not show any differences in the 50% inhibition concentration and maximum inhibitory percentage of rDer p 2A and rDer p 2B sIgE. However, with pool II sera (n = 5; markedly higher sIgE to rDer p 2B than rDer p 2A), the 50% inhibitory concentrations (10 microg/mL vs. 40 ng/mL) and maximum inhibitory percentage (61% vs. 99%) of rDer p 2B sIgE with the two recombinant isoallergens were quite different. rDer p 2B could be quantified with two different 2-site ELISA kits, but rDer p 2A was detected by only one kit.


CONCLUSIONS
We conclude that isoallergens of Der p 2 may have different IgE immune responses. Quantification of Der p 2 with 2-site ELISA kits that adopted mAbs, might be affected by the prevalent form of the isoallergens in reservoir dust.
Park
J W
JW
Department of Internal Medicine, Institute of Allergy, Yonsei University College of Medicine, Seoul, Korea.
Kim
K S
KS
Jin
H S
HS
Kim
C W
CW
Kang
D B
DB
Choi
S Y
SY
Yong
T-S
TS
Oh
S H
SH
Hong
C-S
CS
D000328:Adult; D000911:Antibodies, Monoclonal / Q000276:immunology*; D039741:Antigens, Dermatophagoides / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D060829:Arthropod Proteins; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D011110:Polymorphism, Genetic; D020033:Protein Isoforms; D012882:Skin Tests
D000911:Antibodies, Monoclonal; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; C451163:Dermatophagoides pteronyssinus antigen p 2; D020033:Protein Isoforms; D007073:Immunoglobulin E