Gj. Jakab et al., RESPIRATORY AFLATOXICOSIS - SUPPRESSION OF PULMONARY AND SYSTEMIC HOST DEFENSES IN RATS AND MICE, Toxicology and applied pharmacology, 125(2), 1994, pp. 198-205
Dietary aflatoxin B-1 (AFB(1)) exposure impairs innate and acquired ho
st defenses resulting in increased susceptibility to infections in dom
esticated animals. Experimental studies have confirmed this observatio
n by demonstrating the immunosuppressive effects of AFB(1) ingestion.
In addition to being present in dietary components, AFB(1) is also fou
nd in significant amounts in respirable particles of grain dust. To de
termine the effect of respiratory tract exposure to AFB(1) on host def
enses, rats and mice were exposed either by aerosol inhalation or intr
atracheal instillation to AFB(1). Nose-only inhalation exposure of rat
s to AFB(1) aerosols suppressed alveolar macrophage (AM) phagocytosis
at an estimated dose of 16.8 mu g/kg with the effect persisting for ap
proximately 2 weeks. To determine whether another mode of respiratory
tract exposure, intratracheal instillation, reflected inhalation expos
ure, animals were treated with increasing concentrations of AFB(1) whi
ch also suppressed AM phagocytosis in a dose-related manner albeit at
doses at least an order of magnitude more than that obtained by aeroso
l inhalation. Intratracheal administration of AFB(1) also suppressed t
he release of tumor necrosis factor-alpha from AMs and impaired system
ic innate and acquired immune defenses as shown, respectively, by supp
ression of peritoneal macrophage phagocytosis and the primary splenic
antibody response. These findings demonstrate that experimental respir
atory tract exposure to AFB(1) suppresses pulmonary and systemic host
defenses and indicates that inhalation exposure to AFB(1) is an occupa
tional hazard where exposure to AFB(1)-laden dust is common. (C) 1994
Academic Press, Inc.