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Cotton grown in Stoneville, Mississippi and harvested by three different methods was examined for anticomplementary activity in human serum in vivo. Subjects exposed to cotton dust in a model cardroom for six hours showed changes in C3c and CH50 after exposure to closed boll harvested, bract removed cotton dust when compared with a group of normal, unexposed controls. Decreases in C3c, :C4, and C3A were associated with decreases in FEV1 after exposure to closed boll harvested bract intact cotton dust. The data from this preliminary study suggest in vivo associations between inhalation of cotton dusts and complement which appear to be independent of endotoxin contamination. These findings suggest a relationship between cotton dust inhalation and complement-mediated respiratory impairment.

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.

The pathogenesis of byssinosis has been attributed to several different immunopathologic mechanisms, including a type III (immune complex) pulmonary injury. To further examine this type III theory, sera (Monday preshift) from 59 cotton textile workers were examined by gel diffusion and counterimmunoelectrophoresis for precipitating antibodies to aqueous extracts of cotton bract, carpels, stems, leaves, immature cotton bract, carpels, stems, leaves, immature cotton lint, and cardroom cotton dust. Sera were also collected from 35 nonexposed normal volunteers and examined similarly. No true precipitating antibodies to these extracts could be detected in any of the control or worker serum samples. The aqueous extracts of cardroom cotton dust and cotton stems were found to contain naturally occurring components that precipitated (in agarose gel) beta-lipoprotein and gamma-globulins (mostly IgG) in a nonimmunologic manner. Sera from normal human controls and cotton textile workers all produced identical patterns of reaction with these two extracts. Treatment of these extracts with polyvinylpolypyrrolidone, a specific insoluble adsorbent for polyphenolic tannins, eliminated this pseudoimmune reaction. Although the role this pseudoimmune reaction may play in the pathogenesis of byssinosis is still unknown, it demonstrates the problems associated with laboratory-based investigations of the immunologic aspects of byssinosis.