The role of precipitins and complement activation in the etiology of allergic lung disease

Fungal spores: a critical review of the toxicological and epidemiological evidence as a basis for occupational exposure limit setting

Fungal spores are ubiquitous in the environment. However, exposure levels in workplaces where mouldy materials are handled are much higher than in common indoor and outdoor environments. Spores of all tested species induced inflammation in experimental studies. The response to mycotoxin-producing and pathogenic species was much stronger. In animal studies, nonallergic responses dominated after a single dose. Allergic responses also occurred, especially to mycotoxin-producing and pathogenic species, and after repeated exposures. Inhalation of a single spore dose by subjects with sick building syndrome indicated no observed effect levels of 4 x 10(3) Trichoderma harzianum spores/m(3) and 8 x 10(3) Penicillium chrysogenum spores/m(3) for lung function, respiratory symptoms, and inflammatory cells in the blood. In asthmatic patients allergic to Penicillium sp. or Alternaria alternata, lowest observed effect levels (LOELs) for reduced airway conductance were 1 x 10(4) and 2 x 10(4) spores/m(3), respectively. In epidemiological studies of highly exposed working populations lung function decline, respiratory symptoms and airway inflammation began to appear at exposure levels of 10(5) spores/m(3). Thus, human challenge and epidemiological studies support fairly consistent LOELs of approximately 10(5) spores/m(3) for diverse fungal species in nonsensitised populations. Mycotoxin-producing and pathogenic species have to be detected specifically, however, because of their higher toxicity.

Human immune toxicity

This review examines xenobiotic toxicity to the immune system, stressing in particular those aspects of most relevance to humans. Immunotoxicity is examined especially from three points of view: by what immunological component is affected, by classes of foreign agents that adversely affect the human immune system and by critical evaluation of human case reports and epidemics. Mechanisms by which xenobiotics interrupt cytokine networks are emphasized. The concept that microbial agents, both environmental as well as infectious, may act as immunotoxicants, either alone or in synergism with conventional agents is introduced. Instances of human immunotoxicology are critically evaluated in terms of clinical relevance, i.e. whether increased susceptibility to opportunistic infections or tumor emergence takes place in the affected individuals.

Organic dust toxic syndrome: an acute febrile reaction to organic dust exposure distinct from hypersensitivity pneumonitis

Organic dust toxic syndrome is a term recently coined to describe a noninfectious, febrile illness associated with chills, malaise, myalgia, a dry cough, dyspnea, headache and nausea which occurs after heavy organic dust exposure. Organic dust toxic syndrome shares many clinical features with acute farmer's lung and other forms of hypersensitivity pneumonitis, including the presence of increased numbers of neutrophils in bronchoalveolar lavage. However, organic dust toxic syndrome differs from acute hypersensitivity pneumonitis in several respects: the chest X-ray does not show infiltrates, severe hypoxemia does not occur, prior sensitization to antigens in the organic dust is not required and there are no known sequelae of physiological significance, such as the recurrent attacks and the pulmonary fibrosis which may be seen with chronic hypersensitivity pneumonitis. Organic dust toxic syndrome is thought to be much more common than farmer's lung. It is important for clinical and investigational purposes that organic dust toxic syndrome be distinguished from acute farmer's lung.

Allergic broncho-pulmonary aspergillosis: the radiological appearance during long-term follow-up

The radiographs of 100 patients with allergic bronchopulmonary aspergillosis were examined to assess the type and distribution of abnormalities seen during long-term follow-up. Lobar shrinkage occurred almost exclusively in the upper zones but other abnormalities were distributed throughout both lungs. Bronchial wall thickening was the commonest lesion observed and was usually a permanent finding. Consolidation was commonest in the perihilar regions, persisted for up to 20 weeks when transient and was a permanent finding in 10 patients. Dilated bronchi were noted to change in calibre with exacerbations and remissions of the condition. Episodes of transient collapse were segmental, lobar or involved a whole lung. Permanent collapse was always segmental. Massive shadowing, band shadows and 'gloved fingers' were seen less frequently than expected and cavitation was rare. In some patients the chest radiograph was normal between exacerbations of the disease.

Feed-associated respiratory illness in farmers

A variety of respiratory hazards are present in the farm environment. Disorders such as Silo Filler's Disease and Farmer's Lung Disease have been detailed in the literature. A retrospective study of hospital visits for farm-associated lung injury in rural Otsego County, New York during an 11-yr period is reported herein. Twenty-two males and 1 female experienced a total of 26 episodes of illness. Eighty-four percent of the episodes occurred between July 1 and October 31. Four of the 23 individuals died, 2 acutely and 2 after a slowly progressive, debilitating disease. One patient died of suffocation in a silo; 2 patients had Silo Filler's Disease, 1 dying acutely. Of 6 patients with Farmer's Lung Disease, 2 died of progressive fibrosis. The remaining 14 patients suffered an acute febrile illness typified by short duration, clear chest radiograph, and negative serologies. We refer to this as "Silo Unloader's Syndrome" and conclude that it is a more common occurrence in the farm environment than some of the more known disorders. This study demonstrates that occupational lung injury is a problem affecting a young (average age 36 yr) vigorous population with potentially fatal consequences.

Streptomyces albus: a new cause of hypersensitivity pneumonitis

Hypersensitivity pneumonitis is an immunologic lung disease known to be induced by the inhalation of either organic or inorganic antigens, and it may thus be associated with a variety of occupations and microorganisms. To identify an inciting allergen, environmental, bacteriologic, immunologic, and bronchial challenge studies must be employed. These techniques were used to demonstrate that a bacterium uniformly present in processed dirt, Streptomyces albus, was responsible for a biopsy-proven case of hypersensitivity pneumonitis.

Levels of complement factors in human serum during immediate and late asthmatic reactions and during acute hypersensitivity pneumonitis

In 16 asthmatic patients and in four subjects suspected of having hypersensitivity pneumonitis, serum levels of CH50, C3, C4, C5 and factor B were measured before, between 10 and 20 min, between 5 and 7 h and, in the latter group, also 24 h after allergen challenges provoking type I bronchial reactions or acute hypersensitivity pneumonitis. There was a significant decrease in one of the complement factors in two patients during the immediate asthmatic phase, but in no patient during the late asthmatic phase and in no patient with hypersensitivity pneumonitis. On the other hand, significant increases of C3, C4, and/or CH50 were seen in five patients during immediate asthmatic reactions, in seven patients during late asthmatic reactions and in all cases with hypersensitivity pneumonitis. However, with respect to the particular complement factors the vast majority of the patients showed no appreciable change. Investigations of C3 split products, which were done in seven patients gave negative results. No correlations existed between the changes in the levels of complement factors to increases of Raw, decreases of DLCO, size of skin test reactions or RAST scores. The cause and pathophysiological role of the non-uniform behaviour of serum complement levels after inhalation challenges is not yet clear; obviously both consumption and formation of complement factors take place during allergen-induced asthmatic reactions and hypersensitivity pneumonitis.

Acute experimental pulmonary responses to cardroom cotton dust

Laboratory rabbits were exposed for 60 min to aerosols of dry cardroom cotton dust 4 days/wk (Tuesday through Friday) for 15 consecutive weeks. As a parameter of pulmonary pathophysiology, arterial blood gases were monitored with time after challenge. Post-exposure blood gas analyses at 1 hr showed progressive decreases in arterial oxygen tension, with concommitant increases in arterial carbon dioxide tension and the alveolar-arterial oxygen gradient. These responses appeared to result from acute reversible airway obstruction which caused unequal gas distribution and ventilation-perfusion inequalities. When a group of proven responder rabbits was challenged with cardroom cotton dust which was first treated in a manner which paralleled the preparation of medical grade cotton, only minor decreases in arterial oxygen tension were observed. The data suggest that some, as yet undefined, agent(s) which was removed by the treatment was responsible for inciting the observed pathophysiology.

Immunopatholgenesis of hypersensitivity pneumonitis

This review describes antigenic and host factors of possible significance in the immunopathogenesis of hypersensitivity pneumonitis (HP). Although certain immunologic studies suggest immune complex mechanisms in HP, recent experimental and clinical data accumulated support a role for cell-mediated immunity. In addition, some data support roles for anaphylactic and cytotoxic antibody-mediated reactivity as well. One type of reactivity alone may not be sufficient for production of HP, and local pulmonary immune responses may be most relevant to the pathogensis. Whether immune damage will be produced in an exposed individual or not may depend on the characteristics of the antigenic exposure as well as inherited and acquired individual differences in immunologic reactivity and possibly target organ sensitivity.