Induction of Protective Immunity Against Experimental Amebic Abscess of the Liver (EAAL) Using the Monocyte Locomotion Inhibitory Factor (MLIF) Produced by Entamoeba histolytica

MLIF is an anti-inflammatory oligopeptide produced by Entamoeba histolytica in axenic cultures that among other effects inhibits the locomotion of human peripheral blood monocytes [hence, its name, monocyte locomotion inhibitory factor (MLIF)]. This factor may contribute to the paucity of the late inflammatory reaction found in invasive amebiasis, but this, in turn, may allow for the perfect regeneration of the affected organs (liver, skin) observed upon successful treatment (1). In any event, however, we do not yet know whether E. histolytica actually uses—or even produces—MLIF in vivo. If it does, MLIF may be an evasion factor of the ameba against the inflammatory defenses of the host. We, therefore, attemped to induce protective immunity against experimental amebic abscess of the liver (EAAL) by using a MLIF-KLH complex as an immunogen (2).