الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
 |  | from | 144 |  |  |
| | | from | 144 | | |
Abstract
There has been some debate about the causative agent(s) of byssinosis in cotton and flax dusts. Several hypotheses were put to explain the aetiology of the disease; one of them is the endotoxim hypothes is. While some investigators presented evidences suggesting a role of bacterial and/or mycological endotoxin in the development of the disease? others presented evidences devaluating such role. This study was, consequently, conducted to clarify this obscurity; its specific aims were to study the effects of endotoxinsprepared from microorganisms encountered in cotton and flax dusts on the appearance of respiratory symptoms in sensitized animals, and to assay their antigenicity against the sera. of sensitized animals and of subjects chronically exposed to cotton and flax dusts with different diagnosis. Endotoxins were prepared from the most prevalent twelve bacterial and four mycological strains in air-borne samples collected from the different cotton and flax operat ions. Guinea-pigs were sensitized at four different levels of dosages by repeated (triple) intramuscular injections and further challenged by either intraperitoneal injections or aerosol inhalation of each of the prepared endotoxins. Sera of the sensitized and challenged animals were titered against the endotoxins 1n vitro, using the radial diffusion technique, and .ID vivo, using the ,assi\re outanebus ana.~hylaxis test in rabbits.;’Sera of workers exposed to cotton and . flax dusts and diagnosed as qyssinotics (Grade 11), asthmatic bronchitics, chronic bronchi tics, and free from any respiratory signs and symptoms (25 subjects in each group) were titered against the prepared endotoxins In Litro, and the sera of the byssinotic subjects, only, in vivo. ”J’.ere further tested Data presented in the study showed that the challeng ing of the sensitized animals by either injection or inhalation of the prepared endotoxins did not give riSe to any respiratory symptoms. I~munological testing of the sera of these animals, in vitro and in y_t~, revealed a complete absence of any antigen-antibody reaction. Sera of the workers exposed to cotton and flax dusts did not show any immunological activity towards the tested endotoxinsby the radial diffusion assay, and no positive reaction was obtained between the sera of byssinotic subjects and the endotoxins by passive cutaneous anaphylaxis test. These data indicate that: Ca) the prepared endotoxins may be of different type from the endotoxins in the dusts investigated in -’ some of the previous studies or from the endotox ins that might be formed during the storage of raw cotton, and Cb) ,the absence of circulating antibodies to the pre pared endotoxins in sensitized animals and subjects exposed to cotton and flax dustsCincluding byssinotics ) . The data, however, do not exclude any role of the prepared endotoxins under different experimental conditions, or of other toxins present in air-borne cotton or flax dust (whether endotoxins or exotoxins),in the aetiology of byssi nos is . It is concluded that the results of the present study, generally, devaluate the role of endotoxins as a causative agent to byssinosis. The absence of fever in byssinosis and the fact that years of exposure to cotton dust appear necessary for byssinosis to occur support these results.