Expression of human tissue kallikrein in differentiated HL-60 cells

The kallikrein-kinin system is a mediator of inflammation in humans. In ord er to elucidate the range of expression of human tissue kallikrein and its substrates, high and low molecular weight kininogen, in inflammatory cells in vitro, we examined their biosynthesis in the HL-60 cell line by RT-PCR a nd Southern blot analyses. Prominent expression of tissue kallikrein mRNA o ccurred in untreated promyelocytic cultures as well as in HL-60 cells that were induced to differentiate toward neutrophilic, monocytic, and macrophag ic cells. Under the same inducing conditions, kininogen biosynthesis was un detectable at each differentiation state of HL-60 cultures. These results i ndicate that the myelomonocytic lineage of human leukocytes is a source of tissue kallikrein, which may be secreted as part of the inflammatory proces s.