VOLUME 87 NUMBER 1, PART 2

Abstracts 169

121 The level of Fel d 1 in school dust is suffk%ntfy high to induce symptoms in asthmatics! m mMD.nk6ping. Sweden.

About 50 % of Swedish school chikfren keep pets at home. Thus. there is a possibility that &Men carry cat dander to schools by their clothes. School children with asthma sensitized to animal allergens often get worse when returning to school after vacations. Parents of asthmatic children ascribe worsening of the asthma of their children to exposure to schookfust. Therefore, we decided to investigate whether the levels of Fel d 1 found in schooldust were sufficiently high to be able induce symptoms in asthmatic children sensitized to cat.

Dust was collected by means of a special device with a filter (ALK) connected to a vacuum cleaner, 1100 kW. In 8 classrooms in each of 4 schools, i.e. 32 rooms, dust from the horizontal surfaces of chairs, tables and floors was collected. Fiie m2 of each type of surface was sucked for 5 min.

The amount of fine dust collected was detenined. After mini-extraction. the amount of Fel d 1 was determined by the mabELISA method of M. Chapman et al.

About 0.5 pg of Fel d i/g of fine dust was found in classrooms. This is about 1 /20 of the amount reported from houses with cats. That level induces symptoms in most cat-sensitive patients. However, the skin, conjunc- tival and bronchial sensitivity varies 10s times bet- ween patients with clinical allergy to cat. Thus, if the most sensitive child reacts 1 min after entering a home with cat, then the least sensitive child would react after 70 days. Theoretically, the lower level of Fel d 1 in school dust as compared to homes with cats, means that the most sensitive child would react after 20 minutes and probably all cat sensitive patients would react e.g. with exercise induced asthma after prolonged exposure. Thus, the level of Fel d 1 seems to be suffiiiently high to induce symptoms after prolonged exposure.

122 mvvlRo=AL CCIvrROL AIRBORNE CA-i

A-EN (Fe1 d I-I. F. de Blav. M.D. Cham. T.&E. Platte-Milb, Charlottesville-Vi

To - th; different factor8 which influence airborne cat allergen. we have carried out airborne expewimenta uatng a cascade impactor in two different experimental coax. Cat allergen Fe1 d I was measured using a 2 site monoclonal antibody baaed inwnunaqric assay. Within 30 minures of entering a 3Chn clean roan the cat itself WY found to increase airborne Fe1 d I by 30-90 rig/m’ . Following aerial weekly washing 05 the cat. this increase VMJ reduced to c 7nglm . In order to study the influence of thsrwn: design we kept rhe cat in a mom of SSm far 20 hours/day and modified the roan. Thin roo~.i pan studied with or without fur&hinge and with ni:* exchange reten of 0.2 or 2.4 air ehnngea per hour. Both low ventilation rate and fumi&tngo inomaaed the level of oat allergen when &borne !zvrb were measured 1 hour eher the cat wee r.~.%xed. However. the moot l trtking riding ~8d that the carpet eccmnulatea cat allergen et -we hundred times the level for e poliehed floor, i.r 1OOp.g Fe1 d I/day canpared to -0.u Feld d :. i;,l. In keeping with thta air filtration WM onl. Z;rctive et cleaning the air if : (a) there WM ..J carpet & ; (b) the floor was cleaned first. ‘I%,; resulta ahow that airborne oat allergen can !** .%amattenlly reduced by a unnbtnatioa of w-1 u:d the cat, reducing fumtahtnp. vacutm~ oleantn$ qnd air filtration. Compnriaon with previous raw>& W2B.D. 141, 361) euggertd that the reductiona achieved might be uuffkient to allow a cat wneitive patient to live safely in the e.mne house as a cat.

123 DETERMINANTS OF UPPER AND LOWER AIRWAY RESPOKSES TO CAT EXPOSURE. P.A Wood, M.D., PA Trent, M.A.S., KE Mudd, B.S., SM Bowes, Ph.D. PA Eggleston, M.D. Baltimore, Maryland

In an effort to better characterize the upper and lower airway responses to cat allergen, five volunteers with asthma and cat sensitivity under- went 1 hour environmental challenges in a room containing 2 cats designed to simulate a home environment. Airborne Fe1 d I was collected using a personal monitor, fractionated with a cascade impactor, and quantitated by a monoclonal ELISA. Upper and lower airway responses were assessed using symptom scores, nasal mediator release, and spirometry. Airborne Fe1 d I levels ranged from

13.2 to 107.6 ng/m3 (median 82.1) with a prepond- erance of Fe1 d I on relatively large particles (>60% on particles >17 microns, <IO% on particles (4.1 microns). All subjects complained of lower respiratory symptoms and FEVl changes ranged from 1% to 37% (med 15%). Two of the 5 had late phase responses (&PEFR 24% and 73% at 7 and Y hours, respectively). Asthmatic responses depended on methacholine sensitivity with each subject with a fall in FEVl 115% having a PD20 ‘5 B.U. They were somewhat less dependent on skin test reactivity and airborne allergen concentration and were not at all dependent on the degree of nasal response or the particle size distribution. All subjects also experienced upper respiratory symptoms and 3 of the 5 had significant increases in histamine and/or ‘TAME esterase in nasal lavage fluid.

We conclude that methacholine reactivity is the best predictor of a lower airway response to cat exposure and that acute asthmatic responses can he induced in the virtual absence of small respirahle allergen particles.

124 UETOP-

During operation, devices like the rotorod progressively acquire particle loads which may reduce their adhesive properties. To assess any impact of this process, we compared recoveries by intermittent samplers operatmg for 7.5, l&30 and 60 seconds per repetitive cycle. Imtial24-hour, side-by-side, comparisons of 4 rotobar samplers (12 min. cycle), on 78 days, yielded lower estimates using long vs short interval units prepared with Lubriseal grease. Thereafter, we compared 4 intermittent rotorod units (10 min cycle), coated with silicone grease, and operatin for 24 hours. All samplers achieved 2380- 2400 RPL in less than 3.5 seconds (checked stroboscopically) throughout and had positive brakes. Date were based ~JJ days with mean specific particle levels over 100/M Usin

(from a nearby Burkard trap).

L30* means of like pairs, particle levels (L7 5. Ll

f-6.0 ) were calculated from rods exposed for t i? e respective intervals. A ratio, RL (reflectin was derived: RL= 0.5 (L7 5 + LI5)&0.

loading),

results for three particle &es were: hical

Aerosol Ra eed Altemaria Ganoderma Davdn) K 49 51

Ri‘ 1.86 1.93 1.69

On given days, RL did not vary with specific or total blo enic particle levels. However, surfaces preexpose cf. m winter, and then reused, lost collection capability as a function of total particulate levels (hi-vol.) during initial (winter) exposures. These data imply that surface loading can markedly impair rotorod collection and suggest shorter operating intervals to minimize this tendency.