Cuticular reactivity of the early larval stages of Ascaris suum: Adhesion and degranulation of polymorphonuclear leukocytes on the surface of opsonized larvae of a. suum

Abstract

Binding of serum proteins (opsonization) on the surface of infective and early parasitic larvae of Ascaris suum is necessary to induce the adherence of polymorphonuclear leukocytes (PMN). When larvae are not pretreated in vitro with serum components, PMN do not adhere either to infective stage larvae or to parasitic larvae recovered from non-immune guinea pigs at 16, 25 or 48 h post oral infection. Adhesion of PMN occurs on all larval stages tested when they are first opsonized in vitro with the 7S fraction of immune serum. Opsonization with macroglobulins of immune serum or with Fab fragments of immune 7S protein does not induce the in vitro adherence of PMN. Adhesion of PMN to the larval surface results in reduction of Nitroblue tetrazolium to formazan precipitate at the larval surface, specifically in areas where cells are adherent, indicating oxidative enzyme action at the cuticle/PMN interface.