Cathepsin L proteinase secreted by Fasciola hepatica in vitro prevents antibody-mediated eosinophil attachment to newly excysted juveniles.
Cathepsin L-like activity was demonstrated in the excretory/secretory (E/S) products of Fasciola hepatica newly excysted juveniles (NEJ), 3-week-old, 5-week-old and mature flukes using the fluorogenic substituted 7-amino-4-methylcoumarin substrates Z-phe-arg-AMC, Z-arg-arg-AMC and Z-arg-AMC. Gelatin-substrate polyacrylamide gel analysis revealed that the E/S from each of these stages contained multiple proteolytic enzymes; however, the pattern of proteinases obtained for NEJ E/S differed markedly from that of all other stages examined. The four NEJ proteinases identified were inhibited by leupeptin and Z-phe-ala-diazomethyl ketone indicating that each had cathepsin L-like activity. The E/S products of all four developmental stages contain an enzyme capable of cleaving immunoglobulin at the hinge region, the activity of which is also inhibited by Z-phe-ala-diazomethyl ketone. Using in vitro cell attachment assays we show that the cathepsin L-like proteinase purified from the E/S products of adult F. hepatica can prevent the antibody-mediated attachment of eosinophil to NEJ. These experiments indicate that this proteinase has an important biological function in immune evasion.
Carmona
C
C
School of Biological Sciences, Dublin City University, Glasnevin, Ireland.
Dowd
A J
AJ
Smith
A M
AM
Dalton
J P
JP
D000818:Animals; D000920:Antibody-Dependent Cell Cytotoxicity; D056668:Cathepsin L; D002403:Cathepsins / Q000276:immunology / Q000378:metabolism*; D002448:Cell Adhesion / Q000276:immunology; D003546:Cysteine Endopeptidases; D010450:Endopeptidases; D004804:Eosinophils / Q000166:cytology / Q000276:immunology*; D005210:Fasciola hepatica / Q000201:enzymology* / Q000254:growth & development / Q000276:immunology*; D007074:Immunoglobulin G / Q000378:metabolism; D066298:In Vitro Techniques; D013379:Substrate Specificity
D007074:Immunoglobulin G; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D056668:Cathepsin L