Cleavage of immunoglobulin G by excretory-secretory cathepsin S-like protease of Spirometra mansoni plerocercoid.
When immunoglobulin G (IgG) was incubated with Spirometra mansoni plerocercoid (sparganum), it was cleaved into Fab and Fc fragments. Fab/c fragments were also hydrolysed. The digestion was accelerated by dithiothreitol (DTT), indicating that cleavage of IgG heavy chain was due to a cysteine protease secreted into the medium. The responsible enzyme, of M(r) 27 (+/- 0.8) kDa, was purified by a series of thiopropyl affinity, Sephacryl S-300 HR and DEAE-anion exchange chromatographies, either from worm extracts or from excretory-secretory products (ESP). The purified, thiol-dependent protease showed an optimal activity at pH 5.7 with 0.1 M sodium acetate but was active over the pH range 4.5-8.0. Its activity was inhibited completely by 10(-5) M L-trans-epoxysuccinylleucylamido(4-guanidino) butane (E-64) and 1 mM iodoacetamide (IAA), but by only 53% using the specific cathepsin L inhibitor, Z-Phe-Phe-CHN2 (5 x 10(-5) M). Partial NH2-terminal amino acid sequence was Leu-Pro-Asp-Ser-Val-Asn-Trp-Arg-Glu-Gly-Ala-Val-Thr-Ala-Val which showed 80% homology to human cathepsin S. Immunoblot analysis showed that sera from infected patients exhibited IgE antibody reaction. It is proposed that cleavage of immunoglobulin by an excreted-secreted, cathepsin S-like, allergenic protease is a mechanism of immune evasion used by the sparganum.
Kong
Y
Y
Department of Parasitology, College of Medicine, Chung-Ang University, Seoul, Korea.
Chung
Y B
YB
Cho
S Y
SY
Kang
S Y
SY
D000595:Amino Acid Sequence; D000818:Animals; D000909:Antibodies, Helminth / Q000096:biosynthesis; D002403:Cathepsins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007073:Immunoglobulin E / Q000096:biosynthesis; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism; D007141:Immunoglobulin Fc Fragments / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism*; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017386:Sequence Homology, Amino Acid; D013031:Sparganosis / Q000276:immunology; D013032:Sparganum / Q000201:enzymology* / Q000235:genetics / Q000276:immunology*; D013045:Species Specificity
D000909:Antibodies, Helminth; D007140:Immunoglobulin Fab Fragments; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007073:Immunoglobulin E; D002403:Cathepsins; C028217:cathepsin S