The Presence of Mycotoxin-Associated Fungal Spores Isolated from the Indoor Air of the Damp Domestic Environment and Cytotoxic to Human Cell Lines

One hundred and fifty-two fungal isolates from the air spores of 503 damp, mouldy dwellings in Glasgow and Edinburgh, Scotland, were screened for cytotoxicity against the human embryonic diploid fibroblast lung cell line, MRC-5 (ATTC No. CCL171). At least 37% of the isolates, principally of the genus Penicillium, showed toxicity to the cells when subjected to the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay follow ing a water extraction procedure. When spores of 23 of the isolates were sub jected to extraction with the organic solvent dimethyl sulphoxide, an addition al level of cytotoxicity was observed separate from the water extraction meth ods. Many mycotoxins are known to be sparingly soluble in water. When some of these isolate extracts were exposed to human Chang liver cells (ATCC No. CCL13) and to human normal sternal bone marrow cells, (Detroit 98, ATCC No. CCL18), some additional cytotoxicity was observed. A comparison was also made, in some cases, between results obtained in the MTT and neutral red assays. Organisms exhibiting the greatest cytotoxicity included Penicil lium viridicatum, P. expansum, P. chrysogenum, P. commune and Aspergillus fumigatus.