New roles for mast cells in pathogen defense and allergic disease.

Mast cells (MC) are specialized exocytic cells that lie beneath the external surfaces of the body. For many decades, MCs were thought to primarily function as effector cells for IgE mediated allergic diseases. However, recent evidence indicates that MCs also function as important cells in immune surveillance. When activated by pathogens, MCs initiate innate and adaptive immune responses thereby resulting in protection against pathogens. The question remains if MC activation may also function in establishing immune responses against allergens and hence allergic disease. New studies suggest that MCs are not only the effector cell of allergy but may also be the initiator of allergy.

New roles for mast cells in modulating allergic reactions and immunity against pathogens.

Mast cells (MCs) have primarily been associated with mediating the pathological secondary responses to allergens in sensitized hosts. In view of the recent evidence for a MC role in modulating primary immune responses to pathogens, the likelihood for a role of MCs in influencing primary immune response to allergens has grown. New evidence suggests that MCs drive the development of Th2 responses to allergens, particularly when allergen exposure occurs concomitantly with exposure to pathogen products present in the environment. These new roles for MCs in allergy and infection suggest additional drug targets to prevent the development of allergic disease and allergic exacerbations of established disease.

Safety of a peanut oral immunotherapy protocol in children with peanut allergy.

BACKGROUND: Oral immunotherapy (OIT) offers a promising therapeutic option for peanut allergy. Given that during OIT an allergic patient ingests an allergen that could potentially cause a serious reaction, the safety of OIT is of particular concern. OBJECTIVE: The purpose of this study was to examine safety during the initial escalation day, buildup phase, and home dosing phase in subjects enrolled in a peanut OIT study. METHODS: Skin, upper respiratory tract, chest, and abdominal symptoms were recorded with initial escalation day and buildup phase dosings. Subjects also maintained daily diaries detailing symptoms after each home dosing. A statistical analysis of these data was performed. RESULTS: Twenty of 28 patients completed all phases of the study. During the initial escalation day, upper respiratory tract (79%) and abdominal (68%) symptoms were the most likely symptoms experienced. The risk of mild wheezing during the initial escalation day was 18%. The probability of having any symptoms after a buildup phase dose was 46%, with a risk of 29% for upper respiratory tract symptoms and 24% for skin symptoms. The risk of reaction with any home dose was 3.5%. Upper respiratory tract (1.2%) and skin (1.1%) symptoms were the most likely after home doses. Treatment was given with 0.7% of home doses. Two subjects received epinephrine after 1 home dose each. CONCLUSIONS: Subjects were more likely to have significant allergic symptoms during the initial escalation day when they were in a closely monitored setting than during other phases of the study. Allergic reactions with home doses were rare.