Journal of Applied Physiology, Vol 62, Issue 1 253-258, Copyright © 1987 by American Physiological Society
Histamine release and circulating cells after antigen inhalation in allergic dogs
K. F. Chung, M. L. Osborne, R. J. Corrales, T. W. Evans, L. McCabe, O. L. Frick, J. A. Nadel and W. M. Gold
Histamine can be recovered from the blood of ragweed-sensitized dogs after
aerosol antigen challenge, although its source is unknown. Neutrophils and
eosinophils have been recovered from bronchoalveolar lavage fluid (BALF)
obtained under identical conditions. We investigated the time course of
changes in histamine levels in plasma and BALF taken from
ragweed-sensitized dogs after aerosol challenge. Changes in the numbers of
circulating neutrophils, eosinophils, lymphocytes, monocytes, and platelets
were also studied. After 3 min, total pulmonary resistance (RL) was
maximally increased and systolic blood pressure was maximally decreased.
Histamine levels in plasma and BALF were increased and circulating
eosinophils and neutrophils were decreased. After 15 min, platelet numbers
were reduced. By 90 min, changes in RL, blood pressure, plasma and BALF
histamine concentrations, and circulating neutrophils and eosinophils had
returned to base-line values, but platelet numbers remained significantly
decreased. Sham challenge caused no significant changes in any of these
variables. Intravenous administration of histamine in doses large enough to
attain plasma levels comparable with those achieved after aerosol antigen
challenge resulted in no concomitant rise in BALF histamine levels. We
conclude that antigen challenge in sensitized dogs causes increases in BALF
and plasma histamine levels and is associated with a reduction in
circulating neutrophils, eosinophils, and platelets. It is likely that
antigen causes airway mast cells to release mediators that move down a
concentration gradient from the airways to the pulmonary circulation.
