A double-blind study of the discontinuation of ragweed immunotherapy.
BACKGROUND
Immunotherapy effectively treats the symptoms of allergic rhinitis and improves its pathophysiology. We studied whether the effects of immunotherapy on the early response to nasal challenge with antigen and seasonal symptoms persist after discontinuation.


METHODS
Twenty subjects with ragweed allergy who were receiving immunotherapy and who had nasal challenges performed before initiation of treatment were selected. The patients had been receiving maintenance therapy with aqueous ragweed extract at a dose of 12 microg of Amb a 1 equivalent for a minimum of 3 years, at which point they were randomized to receive either placebo injections or to continue with the maintenance dose. Nasal challenges were performed before and 1 year after randomization. Nasal challenges were monitored by counting the number of sneezes and measuring histamine, N-alpha-tosyl-L-arginine methyl ester-esterase activity, and kinins in recovered nasal lavages. In the same year symptom diaries were collected during the ragweed season.


RESULTS
The initial immunotherapy significantly reduced responses to nasal challenge in both groups. The group continuing to receive active treatment showed no significant changes from the response before randomization. In contrast, the group randomized to placebo treatment showed a partial return of histamine, kinins, and N-alpha-tosyl-L-arginine methyl ester-esterase in nasal secretions and the numbers of sneezes. IgG antibodies to ragweed declined only in the group switched to placebo treatment. Seasonal rises of IgE antibodies to ragweed did not return during the first season after treatment was stopped. Symptoms reported during the ragweed season were not different between the groups.


CONCLUSIONS
One year after discontinuation of ragweed immunotherapy, nasal challenges showed partial recrudescence of mediator responses even though reports during the season appeared to indicate continued suppression of symptoms.
Naclerio
R M
RM
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, USA.
Proud
D
D
Moylan
B
B
Balcer
S
S
Freidhoff
L
L
Kagey-Sobotka
A
A
Lichtenstein
L M
LM
Creticos
P S
PS
Hamilton
R G
RG
Norman
P S
PS
D000293:Adolescent; D000328:Adult; D000485:Allergens; D052179:Antigens, Plant; D004311:Double-Blind Method; D006632:Histamine / Q000032:analysis; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007705:Kinins / Q000032:analysis; D008875:Middle Aged; D017817:Nasal Lavage Fluid / Q000737:chemistry; D009299:Nasal Provocation Tests; D010447:Peptide Hydrolases / Q000032:analysis; D010940:Plant Proteins / Q000008:administration & dosage / Q000627:therapeutic use*; D011058:Pollen / Q000276:immunology; D012008:Recurrence; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology / Q000628:therapy*; D012621:Seasons; D012912:Sneezing / Q000276:immunology
D000485:Allergens; C026967:Amb a I protein, Ambrosia artemisiifolia; D052179:Antigens, Plant; D007074:Immunoglobulin G; D007705:Kinins; D010940:Plant Proteins; D007073:Immunoglobulin E; D006632:Histamine; D010447:Peptide Hydrolases; C023073:tosylarginine methyl ester hydrolase