PubMed Health⌕ Search

Biomedical subjects

C F Hendriksen

Publications and source records attributed to C F Hendriksen.

At least 19 recordsLinked to original sources
PubMed2001

An in vitro approach in quality control of toxoid vaccines.

For routine immunogenicity testing of traditionally produced vaccines, animal tests are required by regulatory authorities, with potency estimated in International Units. A new concept focuses on assuring immunogenicity by monitoring batch-to-batch consistency in production. This concept is used for well-defined biologicals such as hormones. Through the use of immunochemical and bio- and physiochemical techniques the traditional products can be characterised as completely as possible. Developments in in vitro methodologies offer opportunities for immunogenicity testing in vitro. This study describes the possibilities for applying the consistency concept to the traditional products, tetanus and diphtheria toxoids. The sources of variation in these products were studied by flocculation time, SDS-PAGE, biosensor analysis, gel permeation chromatography and in vitro cytokine production studies. Batch-to-batch variation was shown using these in vitro techniques. Results indicate that it is possible to apply the consistency concept in the quality control of traditional vaccines like tetanus and diphtheria toxoids.

Animals↗
PubMed2000

Mepyramine but not cimetidine or clobenpropit blocks pertussis toxin-induced histamine sensitization in rats.

The effects of pertussis toxin (PT) and the role of histaminergic H(1), H(2) and H(3) receptor blockade on the actions of histamine on blood pressure, heart rate, blood gas values, and mortality were studied in anaesthetized rats. Four days after treatment with PT, histamine dose-dependently decreased mean arterial blood pressure (MAP) and PT enhanced the histamine-induced decrease in MAP. In the PT but not in the inactivated PT (IPT) or saline treated group three out of six animals died after the highest dose of histamine (300 mg kg(-1), i.v.) In order to determine the type of histamine receptor that mediates HS, 4 days after PT the selective antagonists mepyramine (H(1)), cimetidine (H(2)) and clobenpropit (H(3)) were administered 20 min before the challenge with histamine. Mepyramine completely inhibited both the enhanced histamine-induced decrease in MAP and mortality brought about by PT. Cimetidine and clobenpropit had no protective effects, but rather enhanced the histamine-induced mortality elicited by PT. The present study shows that PT caused HS in rats which is primarily mediated via H(1) and secondarily via H(2) and H(3) receptors. These results are considered to be a first step in the elucidation of the mechanism(s) of the HS test used in the quality control of acellular pertussis vaccine.

Animals↗
PubMed1999

Evaluation of toxin neutralisation in test systems for diphtheria antibody assessment.

Over the past years, various authors have reported that the amount of toxin used in toxin neutralisation (TN) assays for diphtheria appears to influence the resulting relative antibody titre. Antibody affinity is thought to be an influencing factor. To confirm this observation and study the underlying mechanism of toxin neutralisation, a panel of sera was generated, differing in species of origin (mouse, guinea pig, and rabbit) and in affinity by using different immunisation schedules. The panel was then tested in relevant TN test systems for diphtheria antibody titration, namely the VERO cell test, the Toxin Binding Inhibition (ToBI) assay and the in vivo skin test in guinea pigs. A hyperimmune equine reference serum was used as the standard. Antibody affinity was measured in two different affinity ELISAs, the ammonium thiocyanate elution ELISA and the diethylamine inhibition ELISA. The VERO cell test clearly demonstrates the phenomenon; the higher the toxin dose used in the assay, the higher the resulting relative potency. The difference in relative antibody titre decreases as antibody affinity increases. This is especially evident when an equine hyperimmune reference serum is used as the standard. When a species homologous reference is used, the phenomenon is less distinct. The ToBI test, however, does not show the phenomenon. This discrepancy between these two test systems is being further investigated, and comparison will be made with the in vivo TN test. The findings confirm and support earlier observations. It is still unclear exactly which mechanisms are involved in the toxin neutralisation process. Antibody subclasses and class switching could play a role and will be further studied.

Animals↗
PubMed1999

Validation of tests methods in the quality control of biologicals.

With increasing frequency new methods are being developed for the assessment of the quality of biological products. Before these methods can be considered for regulatory acceptance, their relevance and reliability must be established in a formal validation study. Such a study should be tailor-made, depending on the particular purpose and goal of the new method. However, a set of general principles can be given, according to which a validation study should be conducted. Essential ingredients in a validation study are the three Cs for Common sense, Commitment and Communication. Common sense in the design of the study, Commitment of the participating laboratories and Communication between the parties involved. An overview will be given of the various stages of a validation study, the time period needed (Table 1) and a number of problems that can be encountered will be discussed.

Biological Products↗
PubMed1999

Statistical evaluation of numbers of animals to be used in vaccine potency testing: a practical approach.

Some of the guidelines for potency testing of vaccines issued by regulatory bodies such as the European Pharmacopoeia (EP) and WHO are detailed and stringent (e.g. EP monograph for Newcastle Disease (ND) Vaccine (inactivated)), whereas others only stipulate that the number of animals used should be sufficient to meet the required accuracy (e.g. EP monograph for Hepatitis A vaccine (inactivated)). Simulation studies in our laboratory using historical ND potency test data indicated that the number of animals specified in the monograph is too high; a considerable reduction from 10 to seven animals per group does not substantially influence the precision of the results. Multipoint models (e.g. EP monograph for Tetanus Vaccine (adsorbed)) require at least three dilutions per vaccine for testing for response linearity. However, when historical data clearly show that in the range used the response curves are linear, it is superfluous to verify this in every test. Furthermore, linearity has little priority for a valid parallel line assay calculation. A simulation study using historical Diphtheria potency test data showed that calculations using two dilutions per vaccine in relatively small groups of animals produced results comparable to those obtained from the full assay. This procedure still enables calculation of the relative potency, in contrast to the 1 + 1 method, which gives only a pass or fail result, while the number of animals required is only slightly higher. This method could be applied in cases where the 1 + 1 method fails. In conclusion, by providing guidelines on methods in which proven consistency in production and testing may be taken into account, manufacturers are more stimulated to look for other (cheaper) ways to test the potency of a vaccine using less animals.

Animals↗
PubMed1998

Immune responses and side effects of five different oil-based adjuvants in mice.

In this study, five different oil based adjuvants were compared to assess efficacy and side effects. Mice were injected subcutaneously (s.c.) or intraperitoneally (i.p.) with a weak immunogen (synthetic peptide) emulsified in Freund's adjuvant (FA), Specol, RIBI, TiterMax or Montanide ISA50. Efficacy of adjuvants was evaluated based on their properties to induce peptide specific IgG1, IgG2a and total IgG antibodies, native protein cross-reactive antibodies and cytokine production. Side effects were evaluated based on clinical and behavioural abnormalities, and (histo)pathological changes. Although marked differences in isotype profile and height of titre are observed among the different adjuvants used, we found that FA, Montanide ISA50 and Specol worked equally well in the s.c. and i.p. route, TiterMax functioned only when given i.p. and RIBI also did not perform up to par. The number of cytokine (interferon-gamma and interleukin-4) producing spleen cells was significantly higher after injection of RIBI compared with other adjuvants. Injection of FA or TiterMax resulted in severe pathological changes while after RIBI injection minimal changes were observed. In conclusion, high peptide specific antibody levels with limited side effects can be obtained by s.c. injection of peptide combined with Montanide ISA50 or Specol as alternatives to FA.

Adjuvants, Immunologic↗
PubMed1998

Assessment of side effects induced by injection of different adjuvant/antigen combinations in rabbits and mice.

We evaluated the side effects induced by injection of Freund's adjuvant (FA) and alternative adjuvants combined with different antigens. Rabbits and mice were injected subcutaneously, intramuscularly (rabbits) and intraperitoneally (mice) with different adjuvants (FA, Specol, RIBI, TiterMax, Montanide ISA50) in combination with several types of antigens (synthetic peptides, autoantigen, glycolipid, protein, mycoplasma or viruses). The effects of treatment on the animals' well-being were assessed by clinical and behavioural changes (POT and LABORAS assays) and gross and histopathological changes. In rabbits, treatment did not appear to induce acute or prolonged pain and distress. Mice showed behavioural changes immediately after (predominantly secondary) immunization. Injection of several adjuvant/antigen mixtures resulted in severe pathological changes, depending on adjuvant, type of antigen, animal species used and route of injection. Both rabbits and mice showed pathological changes ranging from marked to severe after injection of FA, and ranging from minimal to marked after Specol and Montanide injections. Pathological changes after RIBI injections were severe in rabbits, though slight in mice. After TiterMax injections, pathological changes were moderate in rabbits, though severe in mice. In conclusion, injection of FA according to present guidelines resulted mostly in severe pathological changes, whereas only very few clinical and behavioural signs indicated prolonged severe pain. Our findings indicate that Montanide ISA50 and Specol induce acceptable antibody titres, and cause fewer pathological changes than FA. Thus they are effective alternatives to FA.

Adjuvants, Immunologic↗
PubMed1997

Collaborative study on test systems to assess toxicity of whole cell pertussis vaccine.

A collaborative study has been carried out to establish the precision and accuracy of five test systems for the assessment of the toxicity of whole cell pertussis vaccine. To this end, six vaccines, including both "normal" and "abnormal" products with respect to arbitrary levels of Pertussis toxin and/or potency were tested. The study included in vivo test systems as the Mouse Weight Gain (MWG) test; the current WHO-recommended bioassay to evaluate overall pertussis toxicity and four specific test systems; the Leukocytosis Promotion (LP) test, the Histamine Sensitization (HS) test and in vitro the Chinese Hamster Ovary (CHO) clustering test to estimate pertussis toxin (PT) levels, and the Limulus Amoebocyte Lysate (LAL) test to evaluate endotoxin levels. In addition, participants were also asked to estimate potency by the Mouse Protection test according to Kendrick (MP). Fourteen laboratories in various countries participated in the study. In almost all participating laboratories, the MWG test was not very accurate in evaluating the overall toxicity of whole cell pertussis vaccines. In addition, statistical significant interlaboratory variation was frequently seen. The specific toxicity tests (LP, HS, CHO and LAL test) appeared to be more accurate, but large interlaboratory variation was seen, statistically significant at P < 0.05 for LP test, CHO test and LAL test. Significant variation in test results also occurred in the potency test. Furthermore, the discriminative power of the MP test between different levels of potency was low. It was concluded that, on the condition of optimization and stringent standardisation, HS and CHO test and in particular LP test might be more appropriate to assess PT activity than the MWG test provided that the tests are optimised and stringently standardized. An inhibition ELISA was used to estimate levels of PT. This test could be of value for prescreening purposes. The LAL test should be used to estimate endotoxin activity. The value of the MP test, as a model to assess potency, is disputed.

Animals↗
PubMed1997

Increased adjuvant efficacy in stimulation of antibody responses after macrophage elimination in vivo.

To investigate whether macrophages influence the efficacy of adjuvants, we locally eliminated lymph node macrophages with dichloromethylene diphosphonate containing-liposomes before primary immunization. After macrophage elimination, animals were immunized with a soluble antigen (TNP-KLH; 2,4,6-trinitrophenyl-keyhole limpet haemocyanin) either in phosphate-buffered saline (PBS), in complete Freund's adjuvant (CFA), or in Specol is a water-in-oil emulsion, considered to be less aggressive than CFA, but equally effective. A secondary immunization followed with TNP-KLH. In vivo macrophage elimination before Specol/TNP-KLH immunization resulted in increased adjuvant efficacy as measured by (primary) antibody responses. This suggests that the activity of Specol is not primarily mediated through macrophages but rather through other antigen-presenting cell types (e.g. dendritic cells, B cells, fibroblasts). The overall quality of produced antibodies, in terms of isotype distribution and affinity maturation, remained the same. After primary injection, CFA/TNP-KLH immunization resulted in significantly higher antibody responses in macrophage-depleted animals and antibody responses did not increase significantly after secondary immunization. However, a booster effect was found when macrophages were not eliminated before CFA/TNP-KLH immunization, suggesting that the presence of macrophages during the first weeks of the primary immune response is essential for the induction of an effective secondary response in CFA immunizations. In conclusion, macrophage depletion before immunization with a soluble T-cell-dependent antigen combined with Specol may enhance specific antibody responses without changing the isotype or affinity of the antibodies.

Adjuvants, Immunologic↗
PubMed1996

A short history of the use of animals in vaccine development and quality control.

Man has been using animals since early times to gain an insight into health, illness and death. The oldest known medical standard work, the Corpus Hippocraticum (circa 350 BC), contains descriptions of experiments on pigs. Although the first attempt at immunoprophylaxis dates as far back as the 6th century (variolation was practised in China to protect people against smallpox), it was not until the middle of the 19th century that animal experimentation acquired full scientific status in the development and quality control of immunobiological products. It was Louis Pasteur and Robert Koch who, through studies on animals, succeeded in underpinning the causal relationship between infectious diseases and micro-organisms, thus opening the way to the discovery of effective therapeutic and prophylactic agents for a number of these diseases. In several respects, the experimental animal work carried out in the last decade of the 19th century to find an effective and reliable way of treating and preventing diphtheria determined the use of animals. Many common routine animal tests in the quality control of immunobiologicals arose from diphtheria research. Conversely, diphtheria was one of the first diseases where experimental animal research laid the foundation for effectively reducing child mortality. This had a very profound impact on the attitude of society towards animal experiments in those days and almost completely eliminated the growing influence of the antivivisection movement. The interest in the possibilities of replacement, reduction and refinement (the Three-Rs concept) of the use of laboratory animals is increasing for several reasons, including concern about animal welfare. The root of animal welfare can be traced back to the 18th century with the formulation of utilitarian ethics. One characteristic feature of these ethics was that the interests of any creature which is submitted to any procedure should be taken into consideration. This presentation sets out some major historical contributions of animal experiments to the development and quality control of immunobiologicals. Attention is also paid to the changing attitude of society towards animal experiments and its impact on the development of alternative methods. It is concluded that, although animal experiments have played an important part, a new area is now beginning in which increasing emphasis will be placed on in vitro methods.

Animal Testing Alternatives↗
PubMed1995

Comparison of adjuvants for immune potentiating properties and side effects in mice.

Four types of adjuvants were evaluated as alternatives to the use of Freund's complete adjuvant in mice. The adjuvants evaluated included a water-in-oil emulsion (Specol), a microorganism (Lactobacillus), performed immune-stimulating complexes (ISCOM) containing rabies virus glycoprotein and a saponin, Quil A. The adjuvants and saline were combined with three weak immunogens (a synthetic peptide, a self antigen and a particulate antigen) and given by three different routes (intraperitoneal, subcutaneous and dorsal in the foot). The evaluation was based on clinical observations, behavioural studies, pathological lesions and capacity to support immunological responses to weak immunogens. Lesions were most severe after injection of antigen combined with Freund's adjuvant or Quil A, mild to moderate with Specol and minimal with Lactobacillus, iscom conjugates or saline. Despite pathological changes, no signs of prolonged pain or distress could be demonstrated based on clinical observations and behavioural studies. Minimal immunological responses were found after injection of antigen in combination with saline or Lactobacillus. T-cell activation and high antibody responses were found after injection of antigen-iscom conjugates or antigen in Freund's adjuvant emulsions. After Specol/antigen immunisations T-cell activation was demonstrated and high antibody titres were found except for Specol/self antigen immunisations. Presented data suggest that Specol is a possible alternative to Freund's complete adjuvant for the induction of an immune response against weak immunogens except possibly self antigens, for which performed iscoms seem very suitable.

Adjuvants, Immunologic↗
PubMed1995

Change in locomotor activity pattern in mice: a model for recognition of distress?

Recognition and assessment of pain and distress is made by observing common clinical and behavioural signs. Observation usually occurs during a limited period of time and results can be biased by interpretation of an individual observer. To improve objective assessment of distress we studied the locomotor activity pattern of mice during a 24-h interval. As a reference compound, Freund's complete adjuvant (FCA) was used. Mice were injected intraperitoneally with different doses FCA (0, 0.1, 0.2 and 0.5 ml) and observed for 5 to 7 days. Animals did not appear to be in pain and seemed to have a normal activity and behaviour pattern at first sight, however FCA induced a dose-dependent decrease of body weight. Open field activity (total distance run) measured during a limited period of time was not altered as a result of FCA. However, nocturnal activity was dose dependently decreased during the first 3 to 4 nights after treatment with FCA. The data presented indicate that using locomotor activity patterns over 24 h might be a useful adjunct and an objective approach to assess distress.

Animals↗
PubMed1994

Interlaboratory validation of in vitro serological assay systems to assess the potency of tetanus toxoid in vaccines for veterinary use.

An interlaboratory validation study was carried out in seven laboratories to evaluate the suitability of in vitro serological assay systems for the assessment of the potency of tetanus toxoid in single and multicomponent vaccines for veterinary use. Nine commercial vaccines and one experimental tetanus toxoid preparation were selected for immunization purposes according to Method A of the European Pharmacopoeia. Levels of tetanus antibodies in guinea-pig and rabbit serum samples were estimated by indirect ELISA, toxin binding inhibition (ToBI) test, passive haemagglutination (HA) test and by the prescribed standard toxin neutralization (TN) test in mice. Estimates of potency obtained by in vitro tests and by TN test were in good agreement for the various vaccines tested and for antibody levels of individual serum samples in the range 2.6 IU/ml to 266 IU/ml. Significant (P < 0.05) intralaboratory variation occurred less frequently for ELISA and ToBI test than for HA test. The frequency of significant (P < 0.05) interlaboratory variation was acceptable for the ELISA and the ToBI test but greater variation was observed for the HA test. It is concluded that the ELISA and ToBI tests are suitable in vitro assay systems for assessing the potency of tetanus toxoid in batches of single and multicomponent vaccines for veterinary use. Rigid standardization of the HA test is essential before this test can be used for the same quality control purpose.

Animals↗
PubMed1994

Evaluation of several adjuvants as alternatives to the use of Freund's adjuvant in rabbits.

In three experiments we evaluated several types of adjuvants as an alternative to Freund's adjuvant (FA). In the first experiment three adjuvant preparations (a water-in-oil emulsion (Specol), a combination preparation of monophosphoryl lipid A + trehalose dimycolate + cell wall skeleton and a non-ionic block polymer surfactant (TiterMax)) were evaluated. The adjuvants were combined with three different types of weak immunogenic antigens (synthetic peptide, glycolipid and particulate antigen) and administered following the intramuscular and subcutaneous route. The evaluation was based on clinical, pathological and immunological parameters. The animals did not appear to be severely or chronically impaired by the experiment. After injection of the RIBI adjuvant, side effects of the same severity as with FA were induced, while low antibody titers were produced. TiterMax caused few side effects, while antibody responses were very low. In comparing Specol and FA, Specol had far fewer adverse effects than FA. However, Specol had immunostimulating properties of the same level as FA. In the second experiment, the effect of injected volume of FA on side effects and antibody titer was studied. Immunization of rabbits with a total of 0.5 ml FA at different sites does not seem to increase the immune response when compared with the immune response seen after injection of 0.5 ml FA at one site. However side effects were seen in all the animals. In the third experiment, the side effects following intradermal (i.d.) injection of the adjuvants were studied. After i.d. injection of FA or RIBI, undesirable effects were found. No side effects occurred after i.d. injection of Specol or TiterMax. From the studies it is concluded that Specol is an alternative to FA for hyperactivation of the immune response in rabbits.

Adjuvants, Immunologic↗
PubMed1994

Assessment of immunotoxicity of buprenorphine.

In order to use buprenorphine as an analgesic in immunological experiments, we have studied the potential immunotoxicity of buprenorphine. Three-week-old male Wistar Riv:TOX rats were subcutaneously treated with buprenorphine by injection of 0.1, 0.4, or 1.6 mg/kg body weight per day over a period of 4 weeks. Concentrations used were within the range for analgesia in rats. A slight decrease of body weight gain was observed at the highest dose in one but not in a duplicate study. Decreased liver weights were observed in all dose groups. Histopathologically glycogen storage was decreased and fatty vacuolation was found to be increased starting from the lowest dose group. The relative but not absolute weight of the lungs was slightly increased at the lowest dose, this phenomenon was therefore not dose-dependent. Histopathologically, a dose-dependent increase in interstitial pneumonia in the lung was found. At the 2 higher dose levels the weight of the adrenal glands was increased. No haematological changes were found, nor were there effects on bone marrow. In one of 2 studies indications of potential immunotoxicity noted were: an increased weight of the thymus, as well as an increased weight of popliteal and mesenteric lymph nodes. No effects on the weight of the spleen were found. Histologically, there were no changes in the lymphoid organs tested. Total immunoglobulin A concentrations in serum were significantly decreased in the highest dose group, whereas IgG concentrations were increased, albeit not statistically significantly. IgM and IgE concentrations showed no alterations. Two types of immune function assays were carried out: determination of natural killer cell activity and of mitogen responsiveness of spleen cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗