The activity of the synthetic
immunomodulator LF 1695 on the efficiency of two effector cell populations--macrophages and blood platelets--involved in
IgE-dependent cytotoxic processes against parasites, was evaluated.
Oxygen metabolite production and anti-parasite cytotoxic properties of both macrophages and platelets were increased following
LF 1695 treatment in vivo (in rat) or in vitro (in rat and in man). The phagocytic properties of rat peritoneal macrophages were also potentiated by their in vitro incubation with the
drug. In addition to these effector functions, the lysosomal
enzyme content and the migration ability of rat peritoneal macrophages were stimulated after incubation with
LF 1695. In the presence of the
drug, rat macrophages were also shown to produce increased level of IL-1--measured by the
mitogen-induced proliferation of murine thymocytes--when compared to unstimulated phagocytes. Finally, the oral treatment of rats with
LF 1695, in the course of an experimental
infection with schistosome parasites, induced a higher degree of immune protection (80%) against a challenge
infection than untreated, infected control rats (40%). These results bring evidence of a stimulatory role for
LF 1695 on immune effector functions of cells participating to defense mechanisms against multicellular pathogens.