Der f 21, a novel allergen from dermatophagoides farina

Abstract

The Dermatophagoides farina (D. farina) allergens are an important factor contributing to allergic disease. To identify new allergens is important for diagnosis and treatment of allergic diseases. In this study, we sought to characterize the biological activity of Der f 21 of D. farina. The recombinant Der f 21 protein was characterized by western-blot, ELISA and Skin prick test using clinic patient's serum.An allergic asthma mouse model was established with the rDer f 21 as a specific antigen. The results showed that the sera from 28.9% in 38 dust mite allergic children displayed positive results in response to rDer f 21, and 42% in 98 dust mite allergic patients displayed positive response in skin prick test. In addition, Immune inhibition assays showed there was IgE cross-reactivity between rDer f 21 and rDer f 5. Moreover, an allergic asthma mouse model was established. Airway hyperresponsiveness, serum specific IgE, IgG1, eosinophil infiltration in the allergic mice, interleukin-4(IL-4) and interferon-γ (INF-γ) from spleen cells were markedly increased in the allergic mice. The results demonstrate that Der f 21 is a novel allergen.

Keywords: Allergen; Der f 21; airway; biological activity; dust mite.

Figure 1

The allergic activity of rDer f 21. A. Immunoblotting analysis of specific IgE reactivity to allergen rDer f 21 in the serum from dust mite allergic children. B. The specific IgE reactivity to allergen rDer f 21 by ELISA. P1-P11, the serum from rDer f 21 positive allergic children; C1-C3, the serum from healthy children. C. IgE binding inhibition to extracts, rDer f 21, and rDer f 5. rDer f 21 (▲) , rDer f 5 (●) and extracts (■).

Figure 2

The allergic activity of rDer f 21 in allergic patients. A. Skin reactivity and severity of DME and rDer f 21 on mite allergic patients. The number of patients with severity of skin reactivity. B. Skin reactivity and severity of rDer f 21 on mite allergic patients. AR: Allergic rhinitis, BA: Bronchial asthma.

Figure 3

Immunostaining of Der f 21 in paraffin-embedded sections of D. farina. A, B. Probe with anti-Der f 21 monoclonal antibody in longitudinal and sagittal mite sections.

Figure 4

Establishment of a mouse model of allergic asthma by rDer f 21. A. Protocol of mouse model of allergic asthma. B. Airway hyper-responsiveness was measured with the unrestrained whole-body plethysmography. The Penh values were recorded when the mice were stimulated with increasing concentration of methacholine after the challenge. C, D. The level of IgE and IgG1 were detected by ELISA.

Figure 5

Effect of rDer f 21 on inducing mouse lung tissue inflammation. A. Light microscopy revealed the inflammatory cell infiltration (arrows) in the lung tissue. B. The number of eosinophil cell was counted in the BLAF.

Figure 6

Specific peripheral immune response induced by rDer f 21. A. The proliferation of splenocytes isolated from the immunized mice was assessed by MTT. B, C. The levels of specific splenocyte IL-4 and IFN-γ were measured by ELISA.