No abstract

Enzymes in flour improver, in particular fungal alpha-amylase, are known to be a significant cause of respiratory allergy in the baking industry. This study measured total inhalable dust and fungal alpha-amylase exposures in U.K. bakeries, mills, and a flour improver production and packing facility and determined whether assignment of job description could identify individuals with the highest exposures to fungal alpha-amylase and inhalable dust. A total of 117 personal samples were taken for workers in 19 bakeries, 2 mills, and a flour improver production and packing facility and were analyzed using a monoclonal based immunoassay. Occupational hygiene surveys were undertaken for each site to assign job description and identify individuals who worked directly with flour improvers. Analysis of exposure data identified that mixers and weighers from large bakeries had the highest exposures to both inhalable dust and fungal alpha-amylase among the different categories of bakery workers (p<.01). Currently, the maximum exposure limit for flour dust in the United Kingdom is 10 mg/m(3) (8-hour time-weighted average reference period). In this study 25% of the total dust results for bakers exceeded 10 mg/m(3), and interestingly, 63% of the individuals with exposure levels exceeding 10 mg/m(3) were weighers and mixers. Individuals who worked directly with flour improvers were exposed to higher levels of both inhalable dust and fungal alpha-amylase (p<.01) than those who were not directly handling these products. Before sensitive immunoassays were utilized for the detection of specific inhalable allergens, gravimetric analysis was often used as a surrogate. There was a weak relationship between inhalable dust and fungal alpha-amylase exposures; however, inhalable dust levels could not be used to predict amylase exposures, which highlights the importance of measuring both inhalable dust and fungal alpha-amylase exposures.

Acid anhydrides are a group of highly reactive chemicals used widely in the formulation of paints and plastics. Exposure to acid anhydrides causes several occupational lung diseases such as pneumonititis and asthma. Whilst anhydrides, specifically trimellitic anhydride (TMA), have been shown to bind to lung tissue in an animal model, further investigation has been hampered by the lack of a reagent which would enable the identification of primary target proteins for the binding of TMA. Our objective was to develop an antibody to TMA which would enable in vitro studies of TMA interactions with lung epithelial proteins. We developed a monoclonal antibody which binds solely to TMA. We have demonstrated that the antibody can be used to detect TMA bound to different human proteins with little non-specific binding to unconjugated proteins. We then exposed cells of the A549 lung epithelial cell line to TMA in vitro and have shown by western blotting that binding occurs in the 20-35 Kd weight range. We have developed a specific and sensitive reagent to detect TMA bound to proteins. We have used this to show that when TMA is incubated with a lung epithelial cell line, that the TMA binds to proteins with a restricted molecular weight range. These results suggest that the current paradigm for the detection of IgE to small molecular weight reactive chemicals, which presupposes that the chemical binds to serum albumin, may need further investigation.

Endotoxin is common in workplaces such as farms, grain processing plants and cotton mills, and exposure can lead to a wide variety of respiratory symptoms including organic toxic dust syndrome and chronic bronchitis. We developed an in vitro model to enable us to determine the use of lipopolysaccharide receptor (CD14) expression to act as a biomarker of endotoxin exposure. Whole blood was incubated with endotoxin, human serum albumin (HSA) or phosphate buffered saline (PBS) at 37 C to determine the time course of CD14 expression following in vitro stimulus. Fluorescent-labelled antibodies were used to label CD14 on monocytes, and CD45 on monocytes and lymphocytes. Levels of CD14 and CD45 expression were measured by flow cytometry. Levels of expression were determined on eight different samples at the optimum time point and concentration of endotoxin. CD14 expression on monocytes was upregulated in response to endotoxin exposure (p< 0 0001) and could be measured easily in whole blood samples using flow cytometry 4 h afterexposure. CD45 upregulation in response to endotoxin was monocytespecific (p < 0 0001), there was no significant difference in expression of CD45 on lymphocytes between the PBS and HSA controls and endotoxin-exposed cells (p= 0 6). We have shown that the expression of cell surface CD14 and CD45 was significantly increased following in vitro exposure to endotoxin, and that this response was specific for monocytes. We suggest that the measurement of CD14 on monocytes by flow cytometry may be a useful biomarkerof endotoxin exposure.

We propose that CD14 expression on monocytes may help to determine the mechanism of action of lipopolysaccharide in producing respiratory ill health, and may ultimately play a role in monitoring the health effect associated with LPS exposure in the workplace.