The significance of aminopeptidases and haematopoietic cell differentiation.

Aminopeptidases are a group of enzymes found on the cell surface and in the cytoplasmic compartments of many peripheral blood cell types and their progenitors. Their functional roles include the hydrolysis of several biologically active peptides and growth factors and some have proved to be of diagnostic and prognostic value in leukaemia. These enzymes may also be found in serum as a consequence of non-haematopoietic related diseases and so have been used as indicators of liver damage. Haematopoietic cells in the bone marrow go through a process of growth and differentiation before being released into the peripheral circulation where they fulfill many functional roles. The enzyme activities of some aminopeptidases have been shown to modulate the growth of these cells. In addition, the activities of these enzymes themselves can be regulated by haematopoietic growth factors. However, the mechanisms that regulate their expression and activity are not fully understood. In this report the current literature has been reviewed for evidence of expression, regulation and clinical significance.