Participation of the propeptide on procathepsin D activation of human peripheral lymphocytes and neutrophils.

Flow cytometry was used to test the role of the propeptide of procathepsin D in the activation of human peripheral lymphocytes and neutrophils. A selective inhibition of the activation was achieved by antibodies targeted against the propeptide. Synthetic peptide corresponding to the cathepsin D propeptide had a very similar effect as procathepsin D itself. The interaction of procathepsin D with the cells was blocked by the propeptide as monitored in experiments with fluorescently labeled procathepsin D. Our data indicate that procathepsin D activation of human neutrophils and leukocytes described earlier is mediated through the propeptide of the procathepsin D.