Repeated latex aeroallergen challenges employing a hooded exposure chamber: safety and reproducibility.
BACKGROUND
Bronchial, nasal, and conjunctival challenges are useful for clarifying discordant clinical history (Hx) and skin and/or serologic tests and in assessing semiquantitative changes in biologic sensitivity over time. The objective of this study was to determine the safety and reproducibility of repeated latex-allergen challenges with a hooded exposure chamber (HEC).


METHODS
The HEC system comprises a powered forced-air respirator with a fitted face shield and hood that uses glove-derived latex-allergen associated cornstarch particles (LAC) to expose simultaneously the conjunctiva, nose, and lungs. Serial control and incremental LAC challenges are conducted until an endpoint based on upper and/or lower respiratory tract symptoms and peak expiratory flow rates is reached. Six latex-allergic (Hx and puncture skin test [PST]- and 5/6 radioallergosorbent test [RAST]-positive) subjects were challenged on three separate occasions at least 2 weeks apart. Serial latex PST midpoints and serum anti-latex IgE by RAST were monitored at each visit and at a fourth follow-up visit.


RESULTS
All subjects responded to LAC, but not to air or control cornstarch administered as controls. All responses were confined to mild symptoms of allergic rhinoconjunctivitis and/or asthma that either resolved spontaneously or were reversed with inhaled albuterol. No subject experienced a systemic or delayed reaction. There were no significant changes in the endpoint LAC doses over the three challenge visits (P>0.2). The mean coefficient of variation for log2 endpoints within-subjects was 17.3+/-17.2% (SD). The serum latex-specific IgE was not significantly boosted by the three challenges (P>0.2). The concentration of latex extract necessary to produce an 8-mm wheal by PST was not significantly changed during the study (P>0.1), indicating that latex sensitivity was not affected by the repeated LAC exposures.


CONCLUSIONS
The results of this study indicate that repeated HEC latex-allergen challenges are both reproducible and safe, and do not increase latex sensitivity.
Kurtz
K M
KM
Department of Medicine, Division of Allergy and Clinical Immunology, Johns Hopkins Asthma and Allergy Center, Baltimore, Maryland 21224, USA.
Hamilton
R G
RG
Schaefer
J A
JA
Primeau
M N
MN
Adkinson
N F
NF
D000280:Administration, Inhalation; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage; D001273:Atmosphere Exposure Chambers; D001985:Bronchial Provocation Tests / Q000009:adverse effects* / Q000295:instrumentation*; D001993:Bronchodilator Agents / Q000008:administration & dosage; D023381:Endpoint Determination; D004869:Equipment Safety; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007840:Latex / Q000009:adverse effects*; D020315:Latex Hypersensitivity / Q000097:blood / Q000139:chemically induced / Q000188:drug therapy; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate / Q000502:physiology; D011237:Predictive Value of Tests; D011852:Radioallergosorbent Test; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012882:Skin Tests; D016387:Women's Health
D001993:Bronchodilator Agents; D007840:Latex; D007073:Immunoglobulin E; D000420:Albuterol