Involvement of granzyme B expression in the enhancement of natural killer activity by beta-endorphin

beta-Endorphin has been reported to enhance natural killer (NK) activity in vitro. However, few studies have examined the precise regulation of the cy tolytic stage of NK cells. We therefore investigated the regulation by beta -endorphin of cytotoxicity-associated molecules such as granzyme B, perfori n, and Fas ligand (FasL) in human CD16(+) NK cells. On semiquantitative rev erse transcription-polymerase chain reaction (RT-PCR) assay, the granzyme B mRNA level apparently increased in CD16(+) NK cells from high responding s ubjects having ratios >1.5 for the LU30 ratio. An increase in intracellular granzyme B molecules was also detected in CD16(+) NK cells by flow cytomet ry. On the other hand, perforin and FasL appeared not to he involved in reg ulation by beta-endorphin. These findings suggest that up-regulation of gra nzyme B expression may be involved in the enhancement of NK activity by bet a-endorphin. (C) 2000 Academic Press.