Prospective observations on stopping prolonged venom immunotherapy.

Area of Science:

• Allergy and Immunology
• Clinical Medicine

Background:

• Venom immunotherapy (VIT) has established safety and efficacy over a decade.
• Previous studies indicated a risk of systemic reactions upon discontinuation of VIT after 1-2 years.

Purpose of the Study:

• To investigate the duration required for venom immunotherapy.
• To assess clinical reactivity and immunological markers after stopping long-term VIT.

Main Methods:

• A prospective study involving 30 patients who stopped VIT after at least 5 years of therapy.
• Monitoring of skin test sensitivity, serum venom-specific IgE and IgG antibody levels.
• Live sting challenge after 12 months of therapy cessation.

Main Results:

• Significant decrease in skin test sensitivity in 18/30 patients; 23/30 remained positive.
• Serum venom-specific IgE levels were low in 11/30 patients.
• No systemic reactions observed in 29/30 patients after live sting challenge at 12 months off therapy.
• Mean venom IgG levels declined post-therapy but rose after sting challenge without IgE increase.

Conclusions:

• Prolonged VIT may induce isotype-specific suppression of venom IgE antibody response.
• Sustained clinical protection might occur through mechanisms beyond IgG blocking antibodies.
• Further research is needed to confirm these findings and explore underlying mechanisms.