Direct enzyme transfer from lymphocytes is specific

Abstract

Lymphocytes are known to interact directly with other cells in vivo^1,2 and in vitro^3–5, and have recently been shown to transfer the lysosomal enzyme, β-glucuronidase, to fibroblasts from patients with an inherited deficiency of the enzyme⁶. This process requires cell–cell contact, is unaffected by inhibitors of ‘classical’ receptor-mediated endocytosis and is abolished by inhibitors of protein synthesis⁷. Although it is not yet known to what extent the transfer of enzymes by direct cellular interaction is a general phenomenon, a similar mechanism could possibly be involved in the transfer of other lysosomal enzymes in vivo^8–10 and in the exchange of protein in vitro¹¹. We show here that the direct transfer of enzymes from lymphocytes to fibroblasts is restricted to only certain lysosomal enzymes.