IMMUNOTOXICITY SCREENING IN-VITRO USING AN ECONOMICAL MULTIPLE END-POINT APPROACH

An economical multiple endpoint in vitro test battery has been developed for screening chemically induced immune dysfunction. Bearing in mind the complexity of the immune system, different types of immunocompetent cells were used. Cofactor-fortified liver homogenate obtained from rats pretreated with Aroclor (S-9 mix) was employed as an in vitro metabolizing system. The following principal screening design was applied. Immunocompetent cells (peritoneal cells and splenocytes) obtained from female C57B1 mice were treated in vitro for 1 hr. For metabolic activation, chemicals were pretreated with S-9 mix for 2 hr. After the incubation period the cells were washed and different immune function assays (antibody-dependent phagocytosis and lipopolysaccharide-induced release of tumour necrosis factor of thioglycollate-elicited peritoneal macrophages; natural killer cell activity, T- and B-cell blastogenesis, and B-cell antibody synthesis of spleen cell suspensions) were performed. For economy the different spleen cell functions were tested in parallel with aliquots of cells derived from the same chemically treated culture. As an additional parameter the survival of the cells was determined routinely after treatment during all assays. Different chemicals (e.g. tributyltinoxide, 7,12-dimethylbenzanthracene, lead acetate, cyclophosphamide, dexamethasone) were assessed using this system. The results indicate that the in vitro test battery described is a suitable tool for immunotoxicity screening.