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Two batches each of diphtheria-tetanus-acellular pertussis vaccine (DTaP) and that combined with inactivated polio vaccine purchased from foreign markets were tested by mouse body weight decreasing (BWD) toxicity test and Limulus amaebocyte lysate (LAL) test. Three out of the four imported vaccine batches showed the levels of BWD toxicity even comparable to that of DT-whole cell pertussis vaccine. BWD toxicity test is based on endotoxin dose-dependent weight loss of mice and has been used for controlling endotoxin in DTaP. Although of the strong BWD toxicity of the imported vaccines, there was no marked difference in LAL test results between the imported vaccines and Japanese DTaP. However, one imported DTaP batch showed very strong interference with LAL activity of spiked lipopolysaccharide (LPS). The batch interfered not only with LAL activity but also with pyrogenicity and prostaglandin E(2) induction activity. However, the pyrogenicity of the spiked LPS could be recovered from the precipitated fraction of the batch by treating with phosphate buffer to suggest the possibility of recovering in vivo toxicity. As an adequate in vitro test method could not be identified for controlling the safety of the interfering batch, an appropriate in vivo test would be required for testing such vaccines., (Copyright © 2011 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.)

Lipopolysaccharide (LPS) is a major component of the outer membrane of Gram-negative bacteria. It has strong toxicity and might cause sepsis or septic shock. Thus early detection of LPS and neutralization of LPS toxicity are required. We obtained several new LPS-binding peptides using a phage display method. We synthesized 3 of these peptides and analyzed their binding affinity and capacity to LPS. One of these peptides, named Li5-001, showed high binding affinity to LPS and lipid A; the K(d) values were 10 and 1 nM, respectively. Li5-001 showed a high binding capacity to LPS, and was estimated to bind 130 ng LPS/mg, which is higher than that of polymyxin B (80 ng LPS/mg); however, its LPS-neutralizing activity was low. Li5-001 coupled with beads will be useful for eliminating endotoxin contamination from pharmaceuticals. Its low LPS-neutralizing activity allows to be used in the Limulus amebocyte lysate test without eluting LPS from the Li5-001 coupled beads., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)

Haemophilus influenzae type b (Hib) is a major cause of bacterial meningitis among children. Hib conjugate vaccines have effectively prevented Hib infection, and routine immunization with Hib conjugate vaccine has diminished the incidence of the disease in the United States and European countries. Introduction of Hib conjugate vaccines is also required in Japan. However, endotoxin that can carry over from Gram-negative H. influenzae with a purified component may contribute to adverse events following Hib vaccination. In the present study, we examined the endotoxin content in Hib conjugate vaccines. The Hib conjugate vaccine batches, which were produced by a European vaccine manufacturer, were shown to have considerably high endotoxin activity and to vary from 13.9 to 173.7 endotoxin units/dose. These results suggest that it is necessary to monitor the endotoxin content of the vaccine batches to ensure the quality and safety of the vaccines.

Enhancing/interfering effect of antibiotics on endotoxin was evaluated using the endotoxin test and the cell line assay in 28SC cells that has a responsiveness consistent with that of human peripheral blood. When a total of 21 products of seven different kinds of antibiotics were tested, none showed any significant effect on the endotoxin test at its therapeutic dose. However, aminoglycosides showed a significant augmenting effect on IL-6 induction of endotoxin in 28SC cells. Detailed examination of the augmenting effect was made on spectinomycin in the in vitro cell line assay and also in the lethal endotoxin challenge assay in D -galactosamine-treated mice. Spectinomycin also enhanced the endotoxin lethality in D -galactosamine-treated mice. A kinetic analysis in endotoxin-sensitized 28SC cells revealed that the augmentation takes place as quickly as 10 min after spectinomycin treatment. Accordingly, a special caution concerning the augmenting effect was assumed necessary for the safety control of antibiotic products as well as for selecting antibiotics for the therapeutic use.

Some parenteral drugs augment the in vivo action of endotoxin. It is necessary to regulate the overall toxic action of contaminating endotoxin by developing a clinically relevant test method for the safety control of such drugs. Although the responses of human peripheral blood cells (hPBC) to endotoxins to produce tumour necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), and IL-1beta showed considerable variation depending on the endotoxin and also on the individuals used as sources of blood, the responses to each of the endotoxins evaluated relative to that to the Japanese reference standard endotoxin were found to be highly reproducible irrespective of the sources of hPBC. The evaluation procedure based on the relative responsiveness to various endotoxins was shown to be highly effective to detect differences in responsiveness among the endotoxin test, the pyrogen test, and the cytokine induction in hPBC. When eight human monocytoid cell lines were examined, only THP-1 and 28SC cells showed a significant dose-dependent IL-6 production. However, THP-1 failed to show consistency with hPBC in responses to the panel of endotoxins. 28SC cells showed appropriate consistency with hPBC not only in terms of respective responses to the endotoxins but also with regard to detection of the effect of human interferons to augment endotoxin to induce IL-6.

Applicability of the endotoxin test to diphtheria-tetanus-acellular pertussis combined (DTaP) vaccines was examined. We found some DTaP vaccines that strongly interfered with Limulus amoebocyte lysate (LAL) activity of endotoxin without affecting lethal activity of endotoxin in D-galactosamine-treated mice. LAL activity that was interfered in such vaccines increased apparently after the treatment with phosphate buffer at 4 degrees C for a week. The DTaP vaccines that interfered with the endotoxin test showed no significant effect on endotoxin activity in inducing tumor necrosis factor-alpha (TNF-alpha) in rabbit peripheral blood. The in vitro TNF-alpha induction assay was, therefore, suggested to be an appropriate assay method for the quantitative detection of the endotoxin activity in DTaP vaccines.

The pyrogen test and the endotoxin test (the LAL test) have been playing crucial roles in detecting endotoxin in parenteral drugs. The current test methods, however, have disadvantages such as requiring a large number of animals or an inadequacy in evaluation of in vivo endotoxin activity. We attempted to establish a new assay method that can overcome the shortcomings of the current methods. We standardized the in vitro assay method by the use of prostaglandin E2 (PGE2) induction from peripheral blood of rabbits for detecting endotoxin activity. A linear dose-response regression was attained from approximately 0.15 to 5 endotoxin units/ml of Japanese national reference standard endotoxin by the in vitro assay. The assay showed a fine correlation with the pyrogen test but not with the LAL test, when endotoxins from various bacterial sources were tested. The in vitro assay was also shown to have the capability of detecting a synergistic effect of endotoxin and parenteral drugs. The in vitro PGE2 induction test using rabbit blood was, therefore, suggested to be the appropriate test method for guaranteeing the same level of safety of parenteral drugs as the pyrogen test does.

The pyrogen test in rabbits has been replaced by the bacterial endotoxin test. The endotoxin test, however, showed a considerable discrepancy with pyrogenicity and was, therefore, assumed to have an efficacy limitation in directly predicting harmful biological effects of endotoxin. We developed a sensitive in vitro assay method by making use of tumour necrosis factor alpha (TNF-alpha) induction in RAW264.7 cells, which showed a fine correlation with pyrogenicity in rabbits. RAW264.7 cells maintained by serial subculture under an endotoxin-free condition have gained the similar level of sensitivity as the endotoxin test to allow extensive dilutions of a drug for eliminating adverse effects on the cells. The in vitro TNF-alpha induction assay was shown to be capable to detect quantitatively a synergistic effect of a drug and endotoxin. The synergy is assumed necessary to be taken into consideration to define the limit value for the endotoxin test for guaranteeing the similar level of safety as by the pyrogen test., (Copyright 2002 The International Association for Biologicals. Published by Elsevier Science Ltd. All rights reserved.)

To establish the fifth lot (Control 0211) of the Endotoxin 10000 Reference Standard of the National Institute of Health Sciences (the Japanese Pharmacopoeia Endotoxin 10000 Reference Standard), a candidate standard (CS) was prepared and then evaluated. The potency of the CS was assayed against USP Endotoxin Reference Standard (Lot G-1) and defined a s containing approximately 16,000 endotoxin units (EU) per vial by a collaborative study in which 5 laboratories participated. Based on the results, the CS was authorized to be the fifth lot of the Endotoxin 10000 Reference Standard containing 16,000 EU per vial.

To establish the third lot (Control 0201) of the Endotoxin 100 Reference Standard of the National Institute of Health Sciences (the Japanese Pharmacopoeia Endotoxin 100 Reference Standard), a candidate standard (CS) was prepared and then evaluated. The potency of the CS was assayed against USP Endotoxin Reference Standard (Lot G-1) and defined as containing approximately 130 endotoxin units (EU) per vial by a collaborative study in which 5 laboratories participated. Based on the results, the CS was authorized to be the third lot of the Endotoxin 100 Reference Standard containing 130 EU of endotoxin per vial.

The pyrogen test or the endotoxin test has been playing a crucial role in detecting endotoxin in parenteral drugs. The current test methods, however, have disadvantages such as requiring a relatively high number of animals or an inadequacy in direct evaluation of in vivo activity. We made an attempt to establish a new in vitro assay method that can overcome the shortcomings of the current assay methods. We standardized the system of tumor necrosis factor-alpha (TNF-alpha) induction from the peripheral blood of rabbits for assaying endotoxin activity. This in vitro assay showed a linear dose-response regression between 0.1 and 5.0 endotoxin units per milliliter of endotoxin and a definite homogeneity of variance by logarithmically transforming the endotoxin and TNF-alpha concentrations in the reaction mixtures at 5 h of incubation at 37 degrees C. The assay showed a definite correlation with the pyrogen test but not with the endotoxin test when endotoxins from various bacteria were tested.

To establish the second lot (Control 0101) of the Endotoxin 100 Reference Standard of the National Institute of Health Sciences (the Japanese Pharmacopoeia Endotoxin 100 Reference Standard), a candidate standard (CS) was prepared and then evaluated. The potency of the CS was assayed against USP Endotoxin Reference Standard (Lot G-1) and defined as containing approximately 100 endotoxin units (EU) per vial by a collaborative study in which 5 laboratories participated. Based on the results, the CS was authorized to be the second lot of the Endotoxin 100 Reference Standard containing 100 EU of endotoxin per vial.

Fundamental conditions for applying the bacterial endotoxin test to antibiotic products were investigated so as not to affect the level of regulation by the rabbit pyrogen test. According to accuracy evaluation of test methods, the kinetic-turbidimetric and kinetic-colourimetric assays were shown to allow more accurate measurement and, therefore, more sensitive detection of interference to the bacterial endotoxin test than the gel-clot method. In total, 102 antibiotic products were evaluated on their interfering effect to show that the antibiotics could be categorized into three groups depending on intensity of the interference. Although the test was shown to be applicable even to the group showing the strongest interference, it was assumed to be crucial to use appropriate reagents and an accurate test method for avoiding approval of a pyrogenic product. Accordingly, lists of antibiotics are presented to provide limits of concentration for eliminating interference and endotoxin limits for approval to facilitate effective bacterial endotoxin tests., (Copyright 2000 The International Association for Biologicals.)

To establish the fourth lot (Control 0001) of the Endotoxin 10,000 Reference Standard of the National Institute of Health Sciences (the Japanese Pharmacopoeia Endotoxin 10,000 Reference Standard), a candidate standard (CS) was prepared and then evaluated. The potency of the CS was assayed against USP Endotoxin Reference Standard (Lot G-1) and defined as containing approximately 20,000 endotoxin units (EU) per vial by a collaborative study in which 5 laboratories participated. Based on the results, the CS was authorized to be the fourth lot of the Endotoxin 10,000 Reference Standard containing 20,000 EU per vial.

The application of the endotoxin test for globulin and other blood products were investigated by two different limulus amebocyte lysate (LAL) test methods, colorimetric and kinetic turbidimetric methods, using two endotoxin-specific reagents. By the dilution of the blood products in 40 times or more, spiked endotoxin in the products was recovered accurately showing neither inhibition nor enhancement. The definite difference was not shown between the results obtained by the two LAL test methods. According to the method of the endotoxin test described under General Tests of The Japanese Pharmacopeia (thirteenth edition), JPXIII, the maximum valid dilution (MVD) for these products will be calculated to be 40 or more, so it is capable to measure the endotoxin limit for each product. This study indicates that the endotoxin test is applicable to measure the endotoxin content in globulin and other blood products as an alternative method for the rabbit pyrogen test.

The third lot (Control 971) of the Endotoxin Reference Standard of the National Institute of Health Sciences (the Japanese Pharmacopoeia Endotoxin Reference Standard) was prepared. The potency of the new lot was assayed against USP Endotoxin Reference Standard (EC-6) and defined as containing 13,000 endotoxin units (EU) per vial by a collaborative study of 7 laboratories.