Premium
Fasciola hepatica cathepsin L suppresses sheep lymphocyte proliferation in vitro and modulates surface CD4 expression on human and ovine T cells
Author(s) -
Prowse Rhoda k.,
Chaplin Paul,
Robinson H. Clem,
Spithill Terry W.
Publication year - 2002
Publication title -
parasite immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 75
eISSN - 1365-3024
pISSN - 0141-9838
DOI - 10.1046/j.0141-9838.2001.00438.x
Subject(s) - fasciola hepatica , biology , cathepsin l , hepatica , cathepsin , cathepsin l1 , microbiology and biotechnology , cathepsin d , flow cytometry , in vitro , t cell , immunology , biochemistry , immune system , enzyme , helminths
Summary Fasciola hepatica infection has been shown to suppress sheep lymphocyte proliferation in vitro and this is at least partially attributable to excretory/secretory products (ES) released by F. hepatica parasites. We identified a suppressive component in ES by analysing the effect of ES fractions, separated by gel filtration, on the proliferation of sheep T cells in vitro . A major proportion of the suppressive activity in ES was shown to coelute with the cathepsin L proteases: E64, a cysteine protease inhibitor, blocked the suppressive activity of cathepsin L. In order to identify possible mechanisms by which cathepsin L could suppress T cell proliferation, the effect of ES and F. hepatica recombinant cathepsin L (rFhCatL) on the expression of 22 different sheep T cell surface markers was analysed by flow cytometry. Incubation of sheep T cells with ES or two rFhCatL signicantly reduced surface CD4 expression and this effect was prevented in the presence of E64. In similar experiments with human T lymphocytes, ES and rFhCatL were shown to down regulate surface CD4 expression. These results show that F. hepatica cathepsin L both suppresses sheep T cell proliferation and reduces surface CD4 expression on both human and ovine T cells.