Non-ionic block polymer surfactants as immunological adjuvants

The Production of Polyclonal Antibodies in Laboratory Animals. The Report and Recommendations of ECVAM Workshop 35

This is the report of the thirty-fifth of a series of workshops organised by the European Centre for the Validation of Alternative Methods (ECVAM). ECVAM's main goal, as defined in 1993 by its Scientific Advisory Committee, is to promote the scientific and regulatory acceptance of alternative methods which are of importance to the biosciences and which reduce, refine or replace the use of laboratory animals. One of the first priorities set by ECVAM was the implementation of procedures which would enable it to become well informed about the state-of-the-art of non-animal test development and validation, and the potential for the possible incorporation of alternative tests into regulatory procedures. It was decided that this would be best achieved by the organisation of ECVAM workshops on specific topics, at which small groups of invited experts would review the current status of various types of in vitro tests and their potential uses, and make recommendations about the best ways forward (1). This joint ECVAM/FELASA (Federation of European Laboratory Animal Science Associations) workshop on The Immunisation of Laboratory Animals for the Production of Polyclonal Antibodies was held in Utrecht (The Netherlands), on 20-22 March 1998, under the co-chairmanship of Coenraad Hendriksen (RIVM, Bilthoven, The Netherlands) and Wim de Leeuw (Inspectorate for Health Protection, The Netherlands). The participants, all experts in the fields of immunology, laboratory animal science, or regulation, came from universities, industry and regulatory bodies. The aims of the workshop were: a) to discuss and evaluate current immunisation procedures for the production of polyclonal antibodies (including route of injection, animal species and adjuvant ); and b) to draft recommendations and guidelines to improve the immunisation procedures, with regard both to animal welfare and to the optimisation of immunisation protocols. This report summarises the outcome of the discussions and includes a number of recommendations and a set of draft guidelines (included in Appendix 1).

Enhanced immunogenicity of microencapsulated tetanus toxoid with stabilizing agents

PURPOSE

Antigenic proteins encapsulated in biodegradable polyester microspheres (MS) can slowly denature or aggregate, which results in decreased antigenicity. In this study, we have evaluated the ability of co-encapsulated additives to protect against the loss of tetanus toxoid (TT) antigenicity.

METHODS

Antibody responses were analyzed after immunization of mice with TT microencapsulated in the presence of additives (TT-MS-additive).

RESULTS

Immunization with TT-MS-additives gave rise to higher responses than those obtained in the absence of additive. BSA, trehalose. Gamma-hydroxypropylcyclodextrin and calcium salts preserved the immunogenicity of the incorporated antigen with the highest efficacy. Sustained responses were obtained with mixtures of fast and slowly releasing TT-MS containing BSA plus trehalose or calcium salts.

CONCLUSIONS

The selected additives may stabilize the antigen in MS during storage and rehydration in body fluids. Regulated antigen release from MS-based vaccines permits a reduction of the antigen dose and optimization of single-dose vaccine formulations.

Adjuvants: current status, clinical perspectives and future prospects

Adjuvants represent a key issue for vaccines currently under development. Adjuvanticity is linked to the ability to stimulate the T-cell subsets that control the major features of specific immune responses: CD4+ TH1 and TH2 cells and CD8+ cells involved in cytotoxic T lymphocyte responses. Some well-defined immunomodulatory compounds can achieve this stimulation by inducing selective production of appropriate cytokines. Françoise Audibert and Luc Lise review the development of adjuvants and discuss how their combination with suitable vehicles should allow customization of adjuvant preparations capable of inducing protective immune responses better adapted to each type of pathogenicity.

Adjuvants: current status, clinical perspectives and future prospects

Adjuvants represent a key issue for vaccines currently under development. Adjuvanticity is linked to the ability to stimulate the T-cell subsets that control the major features of specific immune responses: CD4+ TH1 and TH2 cells and CD8+ cells involved in cytotoxic T-lymphocyte responses. Some well-defined immunomodulatory compounds can achieve this stimulation by inducing selective production of appropriate cytokines. Françoise Audibert and Luc Lise review the development of adjuvants and discuss how their combination with suitable vehicles should allow customization of adjuvant preparations capable of inducing protective immune responses better adapted to each type of pathogenicity.