M. Profita et al., 15-lipoxygenase expression and 15(S)-hydroxyeicoisatetraenoic acid releaseand reincorporation in induced sputum of asthmatic subjects, J ALLERG CL, 105(4), 2000, pp. 711-716
Background: Recent evidence shows that 15(S)-hydroly-eicoisatetraenoic acid
(15[S]-HETE) can be released and rapidly reincorporated into cellular lipi
ds. These mechanisms exert several immunoregulatory functions that may be r
elevant in airway inflammation.
Objective: Our purpose was to evaluate the levels of both soluble and cell-
associated 15(S)-HETE and to examine 15-lipoxygenase (15-LO) messenger RNA
(mRNA) expression in sputum samples obtained from 10 control and 18 asthmat
ic subjects.
Methods: Levels of 15(S)-HETE were measured by reverse-phase HPLC separatio
n followed by RIA in supernatants and in cell membrane-extracted phospholip
ids after acid hydrolysis. 15-LO mRNA was evaluated by primed in situ hybri
dization (PRINS), Combined immunocytochemistry and PRINS was used to identi
fy the phenotype of cells bearing 15-LO transcripts.
Results: Levels of both soluble and cell-associated 15(S)-HETE were higher
in asthmatic than in control subjects (P < .0001). The percentage of cells
expressing 15-LO mRNA was higher in asthmatic than in control subjects (P <
.01). On double staining for specific cell-type markers and 15-LO mRNA, ma
crophages were the major source for 15-LO.
Conclusion: This study shows that the induced sputum technique allows the e
valuation of 15-LO activity and that soluble, cell-associated 15(S)-HETE an
d 15-LO levels are higher in asthmatic than in control subjects. In additio
n, this study indicates that, in induced sputum, airway macrophages are the
major source of 15(S)-HETE in asthma.