Immunotoxicology in the pharmaceutical industry

Altered Development of Immunocompetence Following Prenatal or Combined Prenatal-Postnatal Insult: A Timely Review

There is an unequal distribution of interest between assessment of immunocompetence at the adult level following the administration of various agents/protocols and evaluation of immunocompetence postnatally subsequent to prenatal insult. This paper reviews the effects of dietary manipulation, selected pharmaceuticals, and certain environmental agents on the functional status of the postnatal immune system after in utero exposure to these agents and protocols. These data are discussed in light of what has also been observed for adult exposure to the same or similar experimental design. A discussion of congenital disorders of immunocompetence is also provided. Alteration in the development of postnatal immunocompetence following prenatal insult may manifest itself in several ways, some of which may reflect a permanent defect while others may be of a transient nature. In either instance, however, it behooves scientists in all arenas to (1) determine the precise nature and magnitude of such developmentally related immunologic deficits and (2) focus on the selection and standardization of the most relevant procedures to be employed in the assessment of immunocompetence.

Immunotoxicological Evaluation: An Overview

Many new drug candidates being developed within the pharmaceutical industry possess immunological activity, which may eventually necessitate an evaluation of potential toxicity to the immune system. At present, no consensus exists on which immunotoxicological procedures are most suitable for incorporation into the routine toxicology studies. This paper describes a few immunological test procedures that seem feasible for extrapolating to man, since similar approaches are now used clinically to evaluate immune reactivity. At present, data demonstrating the efficacy of immunotoxicological assays have been limited to humans exposed to environmental contaminants.

In vitro and in vivo methods in immunotoxicology

One approach to assessment of the immunotoxic effects of drugs and chemicals upon the immune system is briefly described. Appropriate in vivo and in vitro methods and techniques are delineated. It is likely that programs implemented at individual institutions will be modified to specific circumstances.

Immunity, viral pathology and assessment of immune dysfunction in virology and toxicology

General patterns of tissue injury are recognized as characteristic for certain groups of viruses and certain types of host/virus interactions. Acute viral infections, limited in time and space, tend to be accompanied by florid but brief virus replication cycles in tissues and lesions or signs of disease are largely attributable to the cytolytic effects of the virus on host cells. Chronic or persistent viral diseases tend to have low (or difficult to detect) levels of infectious virus on tissues and the lesions tend to be dominated by inflammation, antiviral immune responses and/or host tissue proliferation. At the cellular level, 3 general categories of response to viral infection are recognized: acute cellular swelling with eventual cytolysis, persistent infection, and transformation (neoplastic) infection. Acute cellular swelling may be accompanied by syncytial giant cell formation and/or viral inclusion bodies. Cells persistently infected with viruses though morphologically normal, are increasingly recognized as functionally deficient and may eventually display degenerative change. Transformation to neoplastic growth can be both benign or malignant in cellular expression. In vivo, the initial neutrophilic inflammatory response to virus-induced cellular necrosis is transient and is rapidly superseded by virus-specific inflammation mediated by both humoral and cellular factors and supplemented by the numerous inflammation amplification pathways. Vasculitis, a common but frequently unappreciated event, may produce nonspecific tissue damage via hemorrhage and ischemia in addition to providing a mechanism for egress of inflammatory factors into the areas of virus-induced cellular damage. During the healing phase, repair by substitution (e.g., fibrosis and scarring) or by proliferation of uninfected replacement cells may dominate sites of viral infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of the popliteal lymph node enlargement assay to measure rat T cell function in immunotoxicologic testing

Modifications to the host vs graft response assay (HvGR) which render this technique suitable as an in vivo screen of cell-mediated immune function are described. This method utilizes mitotically inactivated spleen cells from normal heterozygous "nude" rats as stimulator population. We injected these cells into the left hind foot pad of unsensitized Charles River CD rats. Within one week, the recipients are sacrificed and both popliteal lymph nodes removed and weighed. The difference in weight between the challenged and unchallenged node represents the primary T cell response to the injected antigen sequestered in the draining lymph node. Using the immunosuppressive agents cyclophosphamide and dexamethasone we demonstrate the applicability of this assay to detect impaired cell-mediated immune function.