TITLE: The effect of cat removal on allergen content in household-dust samples.
AUTHORS: Wood RA; Chapman MD; Adkinson NF Jr; Eggleston PA
AUTHOR AFFILIATION: Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD.
SOURCE: J Allergy Clin Immunol 1989 Apr; 83(4): 730-4
CITATION IDS: PMID: 2708734 UI: 89215042
ABSTRACT:To evaluate the effect of cat removal on cat-allergen content in the home, serial house dust samples were collected from 15 homes during a 9- to 43-week period after cat removal. Samples were obtained with a hand-held vacuum cleaner, and allergen content was quantitated by a radioimmunoassay specific for the major cat allergen, Fel d 1. Baseline Fel d 1 content ranged from 7.8 Food and Drug Administration units per gram of dust to 436.7 U/gm (median 61.2 U/gm), consistent with levels found in homes with a pet cat. Fel d 1 levels declined gradually in most homes, and by 20 to 24 weeks after cat removal, eight of 15 reached levels consistent with levels found in control homes without cats. In two of those homes, allergen levels fell much more rapidly after aggressive environmental control measures were undertaken. In the other seven homes, however, the decline occurred at a much slower rate, with three homes demonstrating persistent elevations in Fel d 1 content for more than 20 or more weeks. These data demonstrate that the task of allergen elimination from an indoor environment is extremely difficult, even when the source of a specific allergen can be identified and removed.

TITLE: Airborne concentrations and particle size distribution of allergen derived from domestic cats (Felis domesticus). Measurements using cascade impactor, liquid impinger, and a two-site monoclonal antibody assay for Fel d 1.
AUTHORS: Luczynska CM; Li Y; Chapman MD; Platts-Mills TA
AUTHOR AFFILIATION: Department of Medicine, University of Virginia, Charlottesville 22908.
SOURCE: Am Rev Respir Dis 1990 Feb; 141(2): 361-7
CITATION IDS: PMID: 2301854 UI: 90145833
ABSTRACT:The recent development of a sensitive two-site monoclonal antibody immunoassay for the major cat allergen (Fel d 1) has made it possible to make accurate measurements of airborne cat allergen using low volume samplers that do not disturb the room. Houses with cats had from 2 to 20 ng Fel d 1/m³ air compared with less than 0.2 ng/m³ in houses without cats. Using a cascade impactor and a multistage liquid impinger, the particle size distribution of airborne Fel d 1 in nine houses was 75% on particle greater than or equal to 5 microns in diameter and 25% (range, 10 to 62%) on particles less than or equal to 2.5 microns. In a cat vivarium with 12 cats, the air contained 40 ng Fel d 1/m³, but less than 2% was detected on particles less than or equal to 2.5 microns. The air exchange rate in the vivarium (approximately 15 changes/h) appears to be the major difference from domestic houses (less than 0.5 change/h). Repeated studies in one house confirmed a very high proportion (approximately 60%) of Fel d 1 on small particles. During domestic cleaning, the levels of small particle allergen in this house approached those produced by a nebulizer for bronchial provocation, i.e., 40 ng/m³. These results show unequivocally that sufficient airborne Fel d 1 is associated with small particles, which remain airborne for long periods. These findings are strikingly different from previous results obtained with airborne dust mite allergen. The results provide an explanation for the distinctive rapid onset of asthma or rhinitis in patients allergic to cats and a basis for designing a policy to reduce airborne allergen in houses with cats.