Epidermal cells enhance interleukin 4 and immunoglobulin E production after stimulation with protein allergen

Cluster-Immuntherapie bei allergischer Rhinokonjunktivitis

Apart from allergen avoidance, specific immunotherapy (SIT) represents the only potentially curative treatment available to patients with allergic rhinoconjunctivitis. Evidence for its clinical efficacy has been clearly demonstrated in several controlled clinical trials and depends on the allergen to which the patient is sensitive, the quality and total amount of allergen administered, and the SIT schedule. In classic SIT, gradually ascending dosages of the allergen extract are injected subcutaneously (dose-increase period) until the individual maximum dose is reached (dose-maintenance period). Several dosage schedules have been worked out. In cluster immunotherapy, 2-3 injections per day of treatment are given once a week to rapidly reach the maintenance dose. Several cluster schedules have been described. Recent data demonstrate that the frequency and severity of adverse effects in cluster immunotherapy correspond to those in other dosage schedules. As far as safety goes, cluster immunotherapy is an interesting alternative for the dose-increase period. In addition, recent studies reveal that clinical benefits appear sooner with cluster immunotherapy.

A mouse model of the atopic eczema/dermatitis syndrome by repeated application of a crude extract of house-dust mite Dermatophagoides farinae

BACKGROUND

We cultured Dermatophagoides farinae (Df), one of the most common mites in house dust and the most important allergen among natural allergens. With this material, we attempted to produce an animal model of the atopic eczema/dermatitis syndrome (AEDS).

METHODS

We cultured Df mites in high density and prepared a crude extract of Df (DfE) together with the culture medium. We applied the extract to the back skin of NC/Nga and BALB/c mice three times per week for 8 weeks.

RESULTS

In the NC/Nga group, dryness or scaling appeared on the skin, and scratching behavior increased at the second week in the DfE-treated group. Skin erosion and hemorrhage occurred at the fourth week. The epidermis thickened and deepened into the upper dermis, in which mast cells were highly accumulated, corresponding with the skin lesion of AEDS patients. Specific IgE and IgG to DfE and total IgE were elevated in the sera. Mice treated with an extract of mite culture medium did not develop skin lesions. In the BALB/c group, mice developed specific IgE and IgG to DfE, however, no typical skin lesions appeared. Mast cells in the upper dermis did not increase.

CONCLUSIONS

Repeated painting of Dermatophagoides extract produced IgE-associated AEDS-like lesions on the skin of NC mice.

Signals involved in the early TH1/TH2 polarization of an immune response depending on the type of antigen

BACKGROUND

The early production of distinct cytokines by epidermal cells (ECs) in response to antigen exposure may govern the development of TH1 -like immune responses, such as contact sensitivity, or TH2 -like immune responses, such as IgE-dependent allergies of the immediate type, depending on the type of antigen.

OBJECTIVE

The aim of this study was to compare the signals induced by protein allergens with those induced by haptens in ECs and subsequently in local draining lymph node cells (LNCs) or splenocytes.

METHODS

BALB/c mice were primed in vivo with the protein allergens ovalbumin or birch pollen or the haptens 2, 4-dinitrofluorobenzene or trinitrochlorbenzene, respectively, and cytokine and immunoglobulin secretions of responding splenocytes were measured by ELISA after in vitro coculture with ECs. Induction of cytokine mRNA expression in ECs and LNCs was analyzed by reverse transcriptase-PCR.

RESULTS

In the presence of protein allergens, ECs enhance the induction of a TH2 immune response (IL-4 and IgE production of splenocytes), whereas a TH1 immune response (IFN-gamma and IgG2a production) was only induced in the context of haptens. Heat inactivation of ovalbumin did not diminish the development of a TH2 immune response. One direct effect of antigen on ECs was the earlier expression of IL-10 mRNA after stimulation with protein allergens (30 minutes) than with haptens (2 hours) in vitro. By using an in vivo approach, sensitization of the skin with trinitrochlorbenzene, but not with ovalbumin, resulted in an early induction of IL-1beta, IL-12p40, and IFN-gamma mRNA in LNCs, whereas IL-18 was induced by both.

CONCLUSION

These data indicate that the type of antigen strongly influences the type of immune response by eliciting distinct signals already in the epithelium.