Potentiation of allergic bronchoconstriction by repeated exposure to formaldehyde in guinea-pigs in vivo.
BACKGROUND
Indoor formaldehyde (FA) might worsen allergies and be an underlying factor for the increasing incidence and severity of asthma; the exact mechanism, however, remains unclear.


OBJECTIVE
The present study examined the effects of repeated exposure to FA on methacholine- and antigen-induced bronchoconstriction in guinea-pigs in vivo.


METHODS
First, non-sensitized guinea-pigs were transnasally treated with 0.1 or 1.0% FA or saline three times a week for 6 weeks, and increasing concentrations of methacholine (50, 100, and 200 microg/mL) were inhaled at 5-min intervals. Second, guinea-pigs pre-treated with transnasal administration of FA or saline using the same protocol were passively sensitized with anti-ovalbumin (OA) serum 7 days before antigen challenge. Third, guinea-pigs were actively sensitized with OA and pre-treated with transnasal administration of FA or saline using the same protocol. The lateral pressure of the tracheal tube (Pao) was measured under anesthesia and artificial ventilation.


RESULTS
The antigen-induced increase in Pao in actively sensitized guinea-pigs was significantly potentiated by FA exposure in a dose-dependent manner. The dose-response curve of the methacholine-induced increase in Pao in non-sensitized guinea-pigs or of the antigen-induced increase in Pao in passively sensitized guinea-pigs was not altered by FA exposure. Transnasal administration of FA significantly increased the serum anti-OA homocytotropic antibody titre (IgG) as measured by the passive cutaneous anaphylaxis reaction in actively sensitized guinea-pigs.


CONCLUSIONS
The results suggest that repeated exposure to FA worsens allergic bronchoconstriction through enhancing antigen sensitization.
Kita
T
T
Respiratory Medicine, Cellular Transplantation Biology, Kanazawa University Postgraduate School of Medicine, Kanazawa 920-8640, Japan. kitatoshi@med3.m.kanazawa-u.ac.jp
Fujimura
M
M
Myou
S
S
Ishiura
Y
Y
Abo
M
M
Katayama
N
N
Nishitsuji
M
M
Yoshimi
Y
Y
Nomura
S
S
Oribe
Y
Y
Nakao
S
S
D000485:Allergens; D000818:Animals; D000906:Antibodies / Q000097:blood; D016535:Bronchial Hyperreactivity / Q000139:chemically induced; D016085:Bronchoconstrictor Agents; D005404:Fixatives / Q000633:toxicity*; D005557:Formaldehyde / Q000633:toxicity*; D006168:Guinea Pigs; D006967:Hypersensitivity / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D016210:Methacholine Chloride; D010047:Ovalbumin / Q000276:immunology; D010323:Passive Cutaneous Anaphylaxis
D000485:Allergens; D000906:Antibodies; D016085:Bronchoconstrictor Agents; D005404:Fixatives; D007074:Immunoglobulin G; D016210:Methacholine Chloride; D005557:Formaldehyde; D007073:Immunoglobulin E; D010047:Ovalbumin