| Abstrakt: |
To determine whether combined allergen exposure is competitive, additive or synergistic in its effect on lung function, inhalation challenges were performed in 5 asthmatic boys, 12 to 16 years old, with known sensitivity to 2 environmental antigens. Challenges were conducted according to the standards of the American Academy of Allergy on 3 occasions at least 1 week apart, first with each allergen separately then with both simultaneously. Forced Expiratory Volume in 1 sec (FEV1) before study was at least 60% of predicted value. The response to challenge was monitored by serial measurements of FEV1. Challenge ended either when a given provocative dose (PD) produced a 20-35% fall of FEV1(PD20- PD35) or when a concentration of 10,000 PNU/ml produced no effect. Three subjects reacted to the single antigens with a marked fall of FEV1, allowing measurement of PD35for each antigen. In the dual challenge, these subjects reacted to a mean PD of 19% (range: 7 - 32%) of the respective PD35of each antigen. The other 2 subjects reacted to one antigen only and the fall of FEV1was small, only allowing measurement of PD20for that antigen. In the dual challenge these subjects reacted with a 20% fall of FEV1to a PD containing 32 and 47%, respectively, of their single-antigen PD20. These findings support the hypothesis that two antigens inhaled simultaneously exert synergistic effects. (Supported by NIH grant # HL-10436) |
