You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Outcome", "Participant", "Intervention"].

Please return the output as a JSON object of the format: {"Participant" : ["patients with COPD", ...], "Intervention" : ["Atenolol", ...], "Outcome" : ["blood pressure", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Double-blind , placebo-controlled , dose-ranging study of new recombinant hypoallergenic Bet v 1 in an environmental exposure chamber . BACKGROUND Recombinant allergens offer a tool for improving specific immunotherapy ( SIT ) . OBJECTIVE To find the optimal dose of a new hypoallergenic folding variant of recombinant Bet v 1 ( rBet v 1-FV ) as SIT for patients with birch pollen allergy . METHODS Before SIT , thirty-seven adult patients were exposed for eight hours in an environmental exposure chamber ( EEC ) to birch pollen at an average concentration of 3500 ± 500 grains/m ( 3 ) , then randomized to four maintenance dose groups of rBet v 1-FV and one placebo group : 20 μg ( n = 7 ) , 80 μg ( n = 8 ) , 160 μg ( n = 7 ) , 320 μg ( n = 8 ) , and placebo ( n = 7 ) . Patients were treated for 10 weeks with weekly injections and then re-exposed in the EEC . The optimal dose for SIT was assessed using efficacy results from the EEC , IgG responses , and tolerability . RESULTS Thirty-six patients were evaluable for efficacy assessment . The total symptom score significantly decreased in all active groups compared with placebo ( -18.8 % for placebo patients ; -71.9 % , P = 0.0022 for 20 μg ; -75.6 % , P = 0.0007 for 80 μg ; -81.8 % , P = 0.0009 for 160 μg ; -78.3 % , P = 0.0003 for 320 μg ) . IgG1 increased significantly in all active groups compared to placebo . All four active doses were well tolerated , no serious adverse event occurred ; two Grade II reactions , according to EAACI classification , were observed , one in each of the 160- and 320-μg groups . CONCLUSIONS Considering efficacy , immunological response , and tolerability , a maintenance dose of 80 μg of rBet v 1-FV appears to be the ideal dose for allergen immunotherapy in birch pollen allergic patients .
{"Intervention": ["recombinant Bet v 1 ( rBet v 1-FV )", "recombinant hypoallergenic Bet v 1", "environmental exposure chamber", "placebo-controlled"], "Outcome": ["symptom score", "Grade II reactions", "well tolerated", "serious adverse"], "Participant": ["birch pollen allergy"]}