REGULATION OF HUMAN NEUTROPHIL DEGRANULATION BY LY-83583 AND L-ARGININE - ROLE OF CGMP-DEPENDENT PROTEIN-KINASE

The effects of guanosine 3',5'-cyclic monophosphate (cGMP) on the secr etory response of activated human neutrophils were investigated using LY-83583, an inhibitor of soluble guanylate cyclase, and L-arginine, t he precursor of nitric oxide formation. A 30% release of myeloperoxida se (MPO) and lactoferrin (LF) from the primary and specific granules, respectively, was detected by enzyme-linked immunosorbent assay in adh ered neutrophils stimulated with 0.1 muM N-formyl-methionyl-leucyl-phe nylalanine (FMLP) or 20 muM A-23187. LY-83583 (100 muM) inhibited the release of both LF and MPO after stimulation with FMLP or A-23187. Con versely, preincubation of neutrophils with 0.5 mM L-arginine augmented the release of LF and MPO in FMLP- and A-23187-stimulated cells. Conc urrent with the increase in the degranulation response was an elevatio n of cGMP levels in L-arginine-treated cells, while stimulated cGMP le vels were reduced in LY-83583-treated cells. Furthermore, cGMP-depende nt protein kinase (G-kinase) activity was reduced in LY-83583-treated cells, as determined by the delay in G-kinase translocation to interme diate filaments and the inhibition of vimentin phosphorylation. Degran ulation, elevation of cGMP levels, and targeting of G-kinase were also dependent on the concentration of A-23187 or FMLP. These data suggest that activators of neutrophil degranulation mediate this response thr ough a cGMP-dependent protein kinase mechanism.