Endotoxin reactions

Endotoxin is a term often used synonymously with lipopolysaccharide (LPS), a major component of the Gram-negative bacterial cell wall. Endotoxin has been estimated to make up between 3 and 4% of the dry weight of Escherichia coli K12. The LPS molecule consists of a Lipid A component anchored in the outer membrane. This is attached to a series of saccharide units specific for different strains of Gram-negative bacteria. LPS is extremely heat stable and needs to be heated to 180 °C for three hours to ensure inactivation. When injected into the bloodstream, it activates the alternative complement pathway and produces a pyrogenic reaction. Studies on laboratory animals have shown that it can produce severe reactions when inhaled in microgram quantities.  

Many diseases in many industries have been linked to inhalation of endotoxin. Some are shown in Table 7.3. A chronic respiratory disease of textile workers called byssinosis has recently been linked to exposure to endotoxin in dirty cotton. Castallen et al. and Kennedy et al. have shown linear relationships between airborne endotoxin concentration and decrease in lung function. However, there was no relationship between decrease in lung function and the dust levels in the cotton works. The organism most commonly found in cotton and linked for these symptoms is Enterobacter agglomerans. 

Enterobacter agglomerans Flavobacterium sp. Methylophilus methylotrophus Methylomonas methanolica Pseudomonas aeruginosa Serratia marcescens 

Single cell protein production Single cell protein production Downstream processing Military research 

Although endotoxin seems to be the main cause of these symptoms, it has to be recognised that other material apart from the endotoxin, including intracellular products, is being aerosolised by the downstream processing. These other by-products may cause allergic symptoms over and above those caused by endotoxin. 

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P. Stutz, H. Aschauer, J. Hildebrandt, C. Lam, H. Loibner, I. Macher, D. Scholz, E. Schiltze, and H. Vyplel, in A. Nowotny (Ed.), Endotoxin Research Series, Vol. 1, Cellular and Molecular Aspects of Endotoxin Reactions Chemical Synthesis of Endotoxin Analogs and Some Structure Activity Relationships, p. 129. Elsevier, Amsterdam, 1990. 

Myers, K., Truchot, A., Ward, J., Hudson, Y., Ulrich, J. A critical determinant of lipid A endo-toxic activity. In Nowotny, A., Spitzler, J., Ziegler, E. (eds), Cellular and Molecular Aspects of Endotoxin Reactions. Elsevier, Amsterdam (1990), pp. 145-156. 

During the LAL-endotoxin reaction, the solution mixture becomes increasingly turbid. The kinetic... 

Contact urticaria, angioedema, and anaphylaxis Penetration of irritants through gloves Others endotoxin reactions, ethylene oxide, chemical leukoderma... 

Nowotny, a. Molecular aspects of endotoxin reactions. Bact. Rev. 30, 72-98... 

For enzymes intended for parenteral use, the manufacturer must assure that the enzyme preparation is essentially pure and free of endotoxins. Electrophoretic and immunologic tests provide the requisite evidence of purity and homogeneity. Most importandy, the manufacturer must remove toxic impurities, eg, bacterial hpopolysacchati.de (endotoxins) which might cause severe toxic reactions such as anaphylactic shock, fever, and vascular coUapse. 

Pyrogens the endotoxins responsible forfebrile reaction on injection, determined either by the rabbit test or the LAL test. Units are Endotoxin unit/ml (EU/ml). 

Endotoxins are the lipopolysaccharides (LPS) of the outer membrane of Gram-negative bacteria. They trigger inflammatory reactions in the infected organism, activate complement and cause fever or even a septic shock. They act on toll-like receptors. 

Adverse medical reactions caused by endotoxin are witnessed in humans at dosage rates as low as 0.5 ng per kilogram body weight. 

Where the test is conducted as a limit test, the specimen is determined to be positive or negative to the test judged against the endotoxin concentration specified in the individual monograph. Where the test is conducted as an assay of the concentration of endotoxin, with calculation of confidence limits of the result obtained, the specimen is judged to comply with the requirements if the result does not exceed (1) the concentration limit specified in the individual monograph and (2) the specified confidence limits for the assay. In either case the determination of the reaction endpoint is made with parallel dilutions of redefined endotoxin units. 

Limulus Amebocyte Eysate (EAE) Test This test is used to detect the presence of endotoxins in the drug substance. It relies on the coagulation reaction between the endotoxin and the blood of a horseshoe crab. 

There are other ways in which endotoxins may act to produce cotton dust induced airway disease. These include 1) an instrinsic toxicity due to lipid A, responsible for both pyro-genicity and tissue damage 2) a hypersensitivity reaction involving anti-lipid A antibodies. Further, changes in mechanical properties of the lung could be explained by the release of histamine or serotonin caused by endotoxins. 

Provocative Inhalation challenge has been used in an attempt to identify byssinogenic agents (52-54, 83-86). Results of these studies have been Inconclusive, but most positive reactions appear to be due to endotoxin contamination of the dust, or to a toxic or irritant factor (52,53). 

Small airway constriction and recruitment of leukocytes on pulmonary surfaces are prominent, documented responses to the inhalation of cotton dust. Currently, one or both of these effects are generally ascribed to endotoxin (8-10), to antigen-antibody reactions (11), to lacinilene C-7 methyl ether (1, 13), to a low molecular weight ( 1000 daltons), neutral, highly water soluble substance that is stable in boiling water and found in cotton bracts (14), to chemotaxins present in cotton mill dust extracts (15, 16) or to histamine releasing substances (17). 

Endotoxin inhalation has been proposed to explain symptoms of the acute byssinotic reaction ( ) and implicated as the causative... 

Involvement of complement activation in the etiology of the acute byssinotic reaction could explain the pathogenic mechanism of histamine release, non-histamine-mediated bronchoconstriction, chemotaxis, endotoxin and bacterial proteolytic enzyme action. Bronchoconstriction experienced in the acute byssinotic reaction might be attributed to the combined action of C3a and C5a mediated histamine release and non-histamine mediated kinin activity. The presence of PMN in the nasal airways of byssinotics might be explained by the chemotactic action of C5a and the C567 complex. 

Next was the observation that histamine is liberated in tissues by an antigen-antibody reaction and is responsible for a large share of the symptoms of anaphylaxis and the allergic state. Histamine plays an important role in physiological functions of animals and man for example, histamine levels change in certain pathological conditions. Histamine levels or its formation are affected also by various stress situations, such as exposure to chemical compounds, endotoxins, hyper- or hypothermic conditions. 

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