Am. J. Respir. Crit. Care Med., Vol 151, No. 6, 06 1995, 1794-1798.
Dairy farmers have increased methacholine bronchial responsiveness independent of sensitization to mold antigens
M Amishima, M Munakata, Y Ohtsuka, A Satoh, T Takahashi, H Taguchi, Y Nasuhara, M Ohe, I Doi and Y Homma
First Department of Medicine, School of Medicine, Hokkaido University, Sapporo, Japan.
Patients with farmer's lung disease (FLD) and dairy farmers have
nonspecific bronchial hyperresponsiveness. To examine the factors
determining bronchial hyperresponsiveness among dairy farmers, we studied
airway functions, airway responses to inhaled methacholine, serum total IgE
levels, and antigen-specific IgE levels in 37 dairy farmers and 11 local
control subjects. The 37 dairy farmers consisted of three groups; 12
farmers with episodes of FLD (FLD group), 13 farmers with serum antibody to
Micropolyspora faeni (MF) and/or Thermoactinomyces vulgaris (TV) but
without episodes of FLD (Ab(+) group), and 12 farmers without serum
antibodies to MF and TV and without episodes of FLD (Ab(-) group).
Pulmonary function tests showed small airways disorders among farmers (each
of the three groups versus control subjects; p < 0.05). Methacholine
provocation test, utilizing PD35Grs (a cumulative dose of methacholine that
induces 35% reduction in respiratory conductance [Grs]), showed bronchial
hyperresponsiveness in each group of dairy farmers compared with that in
control subjects (Log PD35Grs, mean +/- SEM: 1.22 +/- 0.18, 1.00 +/- 0.17,
and 1.20 +/- 0.20, respectively, versus 2.10 +/- 0.09; p < 0.001).
However, there was no statistically significant difference in bronchial
responsiveness among the three groups of dairy farmers. In addition, there
was no significant difference in serum total IgE levels and specific IgE
antibodies among the four groups. These results suggest that the bronchial
hyperresponsiveness to methacholine among dairy farmers is not due to past
episodes of FLD or sensitization to MF and/or TV, but is possibly due to
the occupational environment of dairy farming.
