SECRETORY LYSOSOMES - A SPECIAL MECHANISM OF REGULATED SECRETION IN HEMATOPOIETIC-CELLS

The secretory, granules of cells derived from the haemopoietic lineage are 'secretory lysosomes' containing both lysosomal hydrolases and se cretory protein. Studies on cytotoxic T lymphocytes (CTLs) have elucid ated several of the mechanisms that regulate protein sorting to, and s ecretion from, this unusual secretory, organelle. In particular, recen t findings from a CTL mutant have led to the hypothesis that CTLs, and other cells of the haemopoietic lineage, use specialized sorting and secretory mechanisms in which the lysosome functions as a regulated se cretory granule.