Consideration on a few aspects of the stability studies post licensure.

Stability studies represent a significant workload for both manufacturers and regulatory reviewers and therefore a careful selection of the study design and of the stability indicator test is required to make sure that the study will provide the relevant information. Moreover, alternatives to the existing regulatory approaches should be favoured in order to better or quicker analyze the impact of a specific change. In this article, examples of alternative approaches are given. For the stability monitoring study, emphasis is put on the bulk stability program. Concerning comparability stability study, two case studies illustrating how accelerated stability studies could be used to support manufacturing changes are presented.

Variability of the inhibition by total immunoglobulin of in vitro autoantibody-mediated erythrophagocytosis by mouse macrophages.

Several autoimmune diseases, mainly autoantibody-mediated, are attenuated by infusion of total IgG (IVIg). The efficacy varies widely from one patient to another. Using an experimental model of in vitro phagocytosis of autoantibody-coated erythrocytes by mouse macrophages, we analysed the possible causes for such a variability. Our results indicated that the efficacy of the phagocytosis inhibition depends upon different factors, such as the isotype and the extent of polymerization of the immunoglobulin used for the treatment as well as the genetic background of the mice and the state of macrophage activation that can be influenced by concomitant viral infection. The development of an in vitro assay for the phagocytic activity of macrophages might improve the selection of patients susceptible to benefit from IVIg treatment.

The mode of action of treatment by IgG of haemolytic anaemia induced by an anti-erythrocyte monoclonal antibody.

In order to gain insight into the mechanisms by which the infusion of IgG can improve some autoimmune diseases, we induced haemolytic anaemia in mice by the injection of anti-erythrocyte MoAbs derived from NZB mice by S. Izui (Geneva). The IgG1 antibody 31-9D induces anaemia by erythrocyte sequestration in the spleen and liver, whereas the IgG2a antibody 34-3C triggers erythrophagocytosis (Shibata et al., Int Immunol 1990. 2:1133). Treatment of mice with pools of either human or mouse IgG clearly attenuated the anaemia induced by 34-3C, but not by 31-9D. Similar protection was obtained with human monoclonal IgGs from myeloma patients. Prior absorption by mouse erythrocytes did not affect the efficacy of the injected IgG. Treatment with Fc fragments also reduced the anaemia. In vitro experiments confirmed that 34-3C, but not 31-9D, triggered erythrocyte phagocytosis by murine macrophages. This process was completely inhibited by addition of polyclonal or myeloma IgG or of human Fc fragments. These results indicate that, in this model of autoimmune pathology, the protective effect of IgG is mediated by its interaction with the macrophage Fc receptors.

[Contribution of cytology and lymphocyte phenotyping in the biological diagnosis in infectious mononucleosis due to Epstein-Barr virus]. / Apport de la cytologie et du phénotypage lymphocytaire dans le diagnostic biologique des mononucléoses infectieuses dues au virus d'Epstein-Barr.

Because infectious mononucleosis is characterized by a T cell proliferation reacting with EBV-infected lymphocytes, we studied the changes in the blood cell counts and in the immunophenotype of the lymphocytes during this infection. The laboratory findings were similar for the different age groups, except in children less than 5 years old in whom we found a significantly less intense CD8+ S6F1+ response. According to this study, virus-specific serodiagnostic tests rarely show evidence of an acute primary EBV infection if the peripheral blood analysis fails to reveal significant changes in the leucocyte counts and in the T lymphocyte profiles. The study of this hematologic picture is a useful tool for the confirmation of infectious mononucleosis; moreover, it could greatly help when diagnostic problems occur.

Rabies ribonucleocapsid as an oral immunogen and immunological enhancer.

The administration of rabies ribonucleocapsid (RNP) by oral as well as parenteral routes was found to prime specific T cells and elicit N-protein-specific antibodies. per os and intramuscular immunization led to the production of antibodies of the IgA and IgG isotypes, respectively. Mice primed orally with RNP produced significantly enhanced amounts of virus-neutralizing antibody, compared with non-immune controls, upon subsequent parenteral booster immunization with inactivated rabies virus. Thus oral immunization with rabies RNP primed cells capable of mediating a secondary systemic response to rabies virus. The results of experiments in which peptide and protein antigens were administered either physically coupled to or mixed with RNP indicate that RNP has an inherent capacity to enhance immune responses.