Development of an Immunological Rationale for the Prevention and Treatment of Parasitic Diseases.

摘要

Preactabular, enzyme-containing secretion emitted by cercariae of Schistosoma Mansoni during the infective process can be quantitatively collected in vitro for experimental purposes. The technique devised uses as the secretion stimulus small concentrations of either of the penetration-stimulating fractions of the natural skin surface lipid stimulus, linolenic or linoleic acid. There is a minimum effective concentration of the linolenic acid stimulus; an excess may decrease activity, as it does stimulated cercarial penetration. Preliminary evidence indicates that enzyme activity of secretion from cercariae from an inconstant snail source varies widely and randomly. Use of a constant snail source of cercariae, on the other hand, provides enzyme which shows a pattern of high activity preceded and followed in the snail patent period by lower activity. It appears, also from initial data, that both the number of cercariae emerging per snail and their penetration capability reflect the enzyme activity pattern. (Author)