[Effect of bacterial phospholipidic extract (EBP) on the immune response in mice toward sheep red blood cells (author's transl)].

Injection in mice of bacterial phospholipidic extract (EBP) stimulates immune responses to sheep red blood cells (SRBC). Immunostimulation was observed mostly for antibody response and to a less extent for delayed-type hypersensitivity (DTH). The adjuvant effect of EBP is dependent on several factors: dose, route and time. Maximal activity was found when mice received 100 to 200 microgram of an intravenous injection of EBP, twenty-four hours before systemic immunization with optimal doses for antibody or DTH response. Subcutaneous injection of EBP did not modify the cellular or humoral immune response to SRBC inoculated subcutaneously in the same or in a different site of EBP. Adjuvant action of EBP was different of those of endotoxin, since the later suppresses the DTH response to optimal dose of SRBC, this effect being abolished with cyclophosphamide pretreatment. EBP inoculated intravenously suppressed the local reaction of a DTH adoptively transferred with immune spleen cells. These results taking together seem to indicate a preferential role of EBP on the accessory cells in the induction or expression of the immune response to SRBC.