Anaphylactic bronchoconstriction in immunized guinea pigs provoked by inhalation and intravenous administration of hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride

Dose-response and time course of specific IgE and IgG after single and repeated topical skin exposure to dry trimellitic anhydride powder in a Brown Norway rat model

BACKGROUND

Trimellitic anhydride (TMA)-induced occupational asthma is thought to be associated with its ability to acylate proteins and to induce production of TMA-specific immunoglobulin (Ig)E. Though the respiratory tract is considered to be a major exposure route leading to airway sensitization, the potential role of dermal exposure producing asthmatic sensitization is not known. The present study examines the ability of dry TMA powder to sensitize Brown Norway rats when applied, topically, to the skin.

METHODS

A patch of hair was carefully clipped with scissors on the rat's back. Dry TMA powder (0.3, 1.25, 5 and 20 mg) was administered on days 0, 7, 14 and 21, and the area occluded with surgical tape overnight after each application. Residual powder recovered from the occluded skin was analyzed by proton nuclear magnetic resonance and was still predominantly TMA. Circulating anti-TMA IgE and IgG were measured by ELISA.

RESULTS

TMA elicited dose-dependent production of specific IgE and IgG. Specific antibodies were detectable 2 weeks after the first TMA exposure and peaked between 3 and 4 weeks.

CONCLUSION

The data suggest that topical skin exposure to dry TMA powder can induce allergic/immunological sensitization as demonstrated by the production of specific antibodies.

Expression of platelet-derived endothelial cell growth factor and vascularity in the nasal mucosa from allergic rhinitis

BACKGROUND

Angiogenesis plays critical roles in various pathological mechanisms. It has been hypothesized that the vascularity in allergic nasal mucosa is different from that in normal mucosa, and that changes in the vascular network contributes the pathogenesis of allergic rhinitis.

OBJECTIVE

To determine whether hypervascularity and overexpression of the platelet-derived endothelial cell growth factor (PD-ECGF), an angiogenic factor, are found in allergic nasal mucosa and whether these two factors are associated with the allergic reaction.

METHODS

We investigated the expression of PD-ECGF and counted microvessels in 51 nasal mucosae (30 samples from patients with allergic rhinitis and 21 samples as control from normal subjects) using an immunohistochemical technique.

RESULTS

PD-ECGF expression in allergic nasal mucosae was significantly higher than that in control mucosae at the interstitium of the lamina propria (P = 0.0024) and nasal gland (P = 0.024). PD-ECGF positive areas were coincident with areas of high vascularity in the sections. The microvessel count in the lamina propria of allergic mucosae was higher than that of control mucosae (P = 0.050). Regarding the correlation with various clinical factors, the total nasal symptom score was significantly associated with both the PD-ECGF expression in the interstitium of the lamina propria (P < 0.05) and in the nasal gland (P < 0.005), as well as with the number of vessels (P < 0.05).

CONCLUSION

PD-ECGF and hypervascularity in the nasal mucosa may be involved in the pathogenesis of allergic rhinitis.

Relationship between IgG1 levels and airway responses in guinea pigs actively and passively sensitized to hexahydrophthalic anhydride

Organic acid anhydrides (OAAs) are industrial chemicals that may cause induction of specific IgE and airway symptoms in exposed workers. They are a good model for studies of relationships between chemical structure and the sensitizing potential of reactive low-molecular-weight compounds. Hexahydrophthalic anhydride (HHPA) is such a compound. This study aimed to evaluate the relationship between specific IgG1 levels and airway responses in a model to predict the sensitizing potential of OAAs. Guinea pigs were either actively or passively sensitized to HHPA. For active sensitization, guinea pigs were injected i.d. with 0.1 ml of olive oil (vehicle) or 0.05, 0.5, or 5% HHPA in olive oil. Passive sensitization was performed by i.p. injection of different volumes of antisera (0.75-6 ml, either unheated to keep IgE or heated to destroy IgE) taken from HHPA-sensitized guinea pigs. Specific antibody levels were evaluated with ELISA and passive cutaneous anaphylaxis. Animals were challenged 16-18 days after active sensitization, or 2 days after passive sensitization, by intratracheal instillation with HHPA conjugated to guinea pig serum albumin (HHPA-GPSA; 0.05% in saline), and the immediate effects on lung resistance (RL), and plasma extravasation, measured as Evans blue dye extravasation, for up to 6 min were recorded. Active sensitization caused production of specific IgG1. Provocation with HHPA-GPSA caused an increase of both RL and Evans blue dye extravasation, which was dependent upon the active sensitization dose. Challenge with HHPA-GPSA in passively sensitized guinea pigs also produced an increase in both RL and Evans blue dye extravasation which was related to the IgG1 level. In the guinea pig model of HHPA-induced airway allergy, the airway responses are closely related to the serum levels of specific IgG1. Thus, the IgG1 levels induced by the immunization may reflect the sensitizing potential of HHPA.