Specific IgE and IgG Responses and Cytokine Profile in Subjects with Allergic Reactions to Biting Midge <i>Forcipomyia taiwana</i>

Abstract

Background:Forcipomyia taiwana is a tiny blood-sucking midge whose habitat covers large parts of Taiwan and southern China. Female midges bite during the day, causing intense pruritis and swelling in allergic individuals. In this study, we investigated the immune responses of different allergic reactions to midge bites. Methods:F. taiwana (midge)-specific IgE, -IgG and -IgG subclasses were examined by ELISA in 62 human subjects. Peripheral blood mononuclear cells (PBMC) from 6 subjects with solely delayed reactions (SDR) to midge bites and 6 nonallergic controls (NAC) were cultured with midge extract at various time points and assayed. Proliferation of PBMC was measured by MTT assay. Expression of cytokine mRNA was measured by real-time PCR and protein levels by cytometric bead immunoassay or ELISA. Protease activity in midge extract was determined by the Azocoll method. Results: Midge-specific IgE among subjects with an immediate reaction were significantly elevated compared to SDR and NAC subjects. There were no differences in the level of midge-specific-IgG, -IgG₁, -IgG₂, -IgG₃ and -IgG₄ among subjects with different biting reactions. Midge extract elicited significantly more PBMC proliferation, higher expression of IFN-γ, IL-10, IL-6 and TNF-α in SDR subjects than in NAC. Protease activity was detected in midge extract. Protease inhibitors E64 and pepstatin suppressed midge-extract-induced IL-8 production. Conclusions: Our results suggest that an immediate reaction to midge bites is IgE-mediated. IFN-γ, IL-6 and TNF-α are involved in delayed reactions to midge bites. A protease-activated pathway may also be involved in the intense, itchy reactions to midge bites.

The Development of a Murine Model for Forcipomyia taiwana (Biting Midge) Allergy

“…From previous studies, immediate reactions to midge bites are IgE-mediated, while patients with delayed type reactions have lympho-histiocytes and eosinophil infiltration at biting sites and their peripheral mononuclear cells proliferate and secret significantly more interferon-gamma (IFN-γ), interleukin-6 (IL-6), and tumour necrosis factor-alpha (TNF-α) in response to midge extracts than the midge non-allergic subjects [5]. However, the mechanisms involved in the development of the midge allergy or induction of tolerance to midge bites are not fully understood.…”

Therapeutic DNA vaccine attenuates itching and allergic inflammation in mice with established biting midge allergy

“…The biting midge, Forcipomyia taiwana, is a very small (1-1.5 mm) blood-sucking insect, which is widely distributed throughout Taiwan and southern China [1]. It is the most prevalent biting insect allergy in Taiwan, and as many as 60% of exposed individuals develop intense itchy reactions to the bites; 58-64% of individuals are sensitized to its major allergen, For t 2 [2][3][4]. The hematophagous genus of Forcipomyia has been reported around the world, including Singapore, Poland, Italy, North India and Mexico [5][6][7][8][9].…”

A Pilot Study for the Establishment of a Bloodsucking Model for Forcipomyia taiwana (Biting Midge)

“…There are currently no reports that F. taiwana acts as a disease vector, but their bites do pose a risk of hypersensitivity and anaphylaxis [10]. A murine model of F. taiwana bite allergy has recently been established, using a two-step sensitization protocol that involved the intraperitoneal injection of mice with F. taiwana whole body extract to study the immunopathologic features of midge allergy [9].…”

“…Female F. taiwana were collected by the human bait method, as previously described [10]. At least 20 female midges were kept in a 1.5 cm (diameter) × 4.5 cm (height) glass vial with a volume of 10 ml, and the vial was covered with tulle to prevent midges from escaping, but which allowed midges to feed on the ears of study rabbits.…”