Rapid desensitization induces internalization of antigen-specific IgE on mouse mast cells.

BACKGROUND: Rapid desensitization transiently prevents severe allergic reactions, allowing administration of life-saving therapies in previously sensitized patients. However, the mechanisms underlying successful rapid desensitization are not fully understood. OBJECTIVES: We sought to investigate whether the mast cell (MC) is an important target of rapid desensitization in mice sensitized to exhibit IgE-dependent passive systemic anaphylaxis in vivo and to investigate the antigen specificity and underlying mechanisms of rapid desensitization in our mouse model. METHODS: C57BL/6 mice (in vivo) or primary isolated C57BL/6 mouse peritoneal mast cells (PMCs; in vitro) were passively sensitized with antigen-specific anti-2,4-dinitrophenyl IgE, anti-ovalbumin IgE, or both. MCs were exposed over a short period of time to increasing amounts of antigen (2,4-dinitrophenyl-human serum albumin or ovalbumin) in the presence of extracellular calcium in vitro or by means of intravenous administration to sensitized mice in vivo before challenging the mice with or exposing the PMCs to optimal amounts of specific or irrelevant antigen. RESULTS: Rapidly exposing mice or PMCs to progressively increasing amounts of specific antigen inhibited the development of antigen-induced hypothermia in sensitized mice in vivo and inhibited antigen-induced PMC degranulation and prostaglandin D2 synthesis in vitro. Such MC hyporesponsiveness was induced antigen-specifically and was associated with a significant reduction in antigen-specific IgE levels on MC surfaces. CONCLUSIONS: Rapidly exposing MCs to progressively increasing amounts of antigen can both enhance the internalization of antigen-specific IgE on the MC surface and also desensitize these cells in an antigen-specific manner in vivo and in vitro.

[Oral rush desensitization for cow milk allergy: Clinical and immunological follow-up]. / Eficacia y seguridad de una pauta rush de inducción de tolerancia oral en pacientes con alergia a proteínas de leche de vaca: evolución clínica e inmunológica.

OBJECTIVE: The aim of this study was to evaluate the safety and efficacy of oral rush desensitization in children with cow milk allergy. MATERIAL AND METHODS: Prospective study. We included IgE-mediated cow milk allergy children over 3 years in 3 Spanish hospitals. Increasing doses of cow milk for 5 days from 1 cc of 1% to 200 cc of pure milk were administered. Clinical follow-up was conducted and we compared specific IgE levels at onset, 6, 12 and 24 months after desensitization. RESULTS: We included 18 children (13 males) between 3 and 14 years (mean 5.96). A total of 271 doses were administered; there were 55 adverse reactions (84% mild). At the end of the protocol, 100% showed some degree of tolerance (39% total). Full tolerance was achieved in 72% of patients after two years. Two children failed to achieve tolerance. There was a significant decrease in the levels of specific IgE to cow milk and alpha-lactalbumin at 24 months, and to casein at 6, 12 and 24 months, compared to baseline. CONCLUSIONS: Oral rush desensitization is a safe and effective therapeutic option for patients with persistent cow milk allergy to medium term.