Extrinsic Allergic Alveolitis

Sometimes referred to as Hypersensitivty Pneumonitis, this disease develops in some individuals who are exposed to dusts , the antigenic components of which result in their sensitization Once sensitized, further exposure to antigen provokes an antibody precipitin-mediated response which can then initiate a Type3 Arthus reaction marked by the onset of a pyrexial episode accompanied by a reduction in forced vital capacity and carbon monoxide transfer factor some six to eight hours after exposure. One of the now many microbial agents known to be allergenic when inhaled is Aspergillus clavatus, a fungus capable of colonising cereal grain. The initial identification of cases of maltworkers lung disease due to this fungus was reported by Riddle H.F.V., et al.(1968) where contaminated barley in an open floor malting was the source of high densities of aerial spores(conidia) inhaled by workers as they turned the barley to enable aeration and the release of carbon dioxide. Further work reported by Channel,Sonia et al.(1969) examined three cases of the disease in some detail. Chest radiographs showed the presence of micronodular shadowing and changes in respiratory function followed the inhalation of dry A.clavatus, conidia.
A large scale survey of Extrinsic Allergic Alveolitis throughout the Scottish Malting Industry was then carried out, the results being reported by Grant I.W.B., et al.(1976) who found that 5.2% of the workforce of 711 men was symptomatic. The immunological and mycological findings from the survey were published by Blyth W., et al.(1977), showing that of the 711 men, 57% were serologically positive for 3 genera of fungi but negative for 6 more. Seropositivity was 22% for Aspergillus fumigatus, 20% for Aspergillus clavatus, 10% for Aspergillus niger, 16% for Cladosporium herbarum and 6% for Penicillium cyclopium. Sera from the 5.2% of men with Extrinsic Allergic Alveolitis showed increased reactivity to mycelial antigens of A. clavatus. Work on alveolitis-inducing substances extracted from the fungus was described by Blyth,W.(1978) showing that they were glycoprotein precipitinogens. Spore walls were particularly rich in allergenic fractions extractable by alkaline hydrolysis. An in depth histopathological study of experimental murine disease was recorded. Blyth,W. and Hardy,J.C.(1982) explored the mutagenic and tumourigenic properties of A, clavatus conidia and looked at phagocytosis using electron microscopy. Mycotoxicosis and granuloma formation in mice was examined by Blyth,W, and Lloyd,M.M(1971).

This website presents a record of hitherto unpublished images of:-
1. Open floor malting in relation to the presence of Aspergillus clavatus.
2. Immunological details.
3. Light and electron microscopy of the inflammatory response in murine extrinsic allergic alveolitis.
4. Light and electron microscopy of phagocytosis of conidia by murine alveolar macrophages'in vivo' and by cultured peritoneal macrophages 'in vitro'.
5. Giant cell phagocytosis of conidia.

6. References

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