Interleukin-8-stimulated polyphosphoinositide hydrolysis in human
peripheral blood lymphocytes
KB Bacon, DG Quinn, JP Aubry and RD Camp
Institute of Dermatology, United Medical School of Guy's Hospital, London,
UK.
We have attempted to provide evidence for the production of inositol
phosphate (IP) metabolites as an indication of specific receptor- mediated
signal transduction in human peripheral blood lymphocytes (PBL) in response
to interleukin-8 (IL-8). IP metabolites were measured, after loading of PBL
with [3H]-D-myo-inositol, by anion exchange high-performance liquid
chromatography (HPLC) and liquid scintillation counting of collected
fractions. In addition, inositol- 1,4,5-trisphosphate (IP3), in extracts
from unlabeled cells, was measured using a specific radioligand binding
assay. Compared with phytohemagglutinin (PHA), which stimulated an increase
in IP metabolites and, specifically, IP3 by greater than threefold, human
recombinant (hr) IL-8 (1 nmol/L) also stimulated an increase in IP
metabolites, as measured by HPLC, and a greater than threefold increase in
IP3. The increase in IP3 was observed as early as 15 seconds after
stimulation with hrIL-8, reaching maximal levels by 30 seconds. To further
assess the signal transduction mechanism involved, the protein tyrosine
kinase inhibitor genistein was added to the cells 10 minutes before
stimulation with hrIL-8. After preincubation of PBL with this inhibitor,
the generation of IP3 in response to PHA (5 micrograms/mL) and hrIL-8 (1
nmol/L) was inhibited by 42% and 51% of control values, respectively. In
contrast to the production of IP metabolites, there were only small
increases in intracellular calcium in response to hrIL- 8 when compared
with PHA.
Volume 81,
Issue 2,
pp. 430-436,
01/15/1993
Copyright © 1993 by The American Society of Hematology
