Nerve growth factor is preformed in and activates human peripheral blood eosinophils.
BACKGROUND
Recent studies have shown that nerve growth factor (NGF) is produced by and can act on several immune-inflammatory cells.


OBJECTIVE
The objective of this study was to study the effects of NGF on human peripheral blood eosinophils and assess whether these cells produce and store NGF.


METHODS
Eosinophils were purified by negative immunoselection (magnetic cell sorting systems, purity 98% to 100%) from 13 subjects (9 to 26 years old) with mild blood eosinophilia, mainly of allergic origin. Eosinophils were incubated with NGF (50 to 1000 ng/mL), and supernatants were collected for measurement of eosinophil peroxidase (EPO, 20 minutes, colorimetric enzymatic assay) and IL-6 (12 hours, ELISA). Eosinophil viability was evaluated by Trypan blue test (days 2, 3, and 4). NGF content in freshly isolated eosinophils, after ultrasound disruption, was determined with a 2-site immunoenzymatic assay. The presence of mRNA for NGF was evaluated by reverse transcription PCR.


RESULTS
NGF caused EPO release (highly significant at 1000 ng/mL NGF). IL-6 release from eosinophils was not higher than IL-6 spontaneously released into culture medium alone. NGF did not significantly affect the number of viable eosinophils. NGF was found in the eosinophil sonicates (1.5 to 17.8 pg/mL per 106 cells). Similarly, mRNA for NGF was detected by reverse transcription PCR in the freshly isolated eosinophils.


CONCLUSIONS
NGF activates human peripheral blood eosinophils from subjects with mild eosinophilia to selectively release inflammatory mediators. Eosinophils store and produce NGF. Therefore the capability of NGF to induce a secretory response and its production and storage by circulating human eosinophils suggest a possible role for NGF in conditions associated with eosinophilia, including allergic disease.
Solomon
A
A
Department of Ophthalmology, Hadassah University Hospital, Jerusalem, Israel.
Aloe
L
L
Pe'er
J
J
Frucht-Pery
J
J
Bonini
S
S
Bonini
S
S
Levi-Schaffer
F
F
D000293:Adolescent; D000328:Adult; D002470:Cell Survival / Q000187:drug effects; D002648:Child; D047209:Eosinophil Peroxidase; D004802:Eosinophilia / Q000097:blood / Q000276:immunology; D004804:Eosinophils / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D006967:Hypersensitivity / Q000097:blood; D015850:Interleukin-6 / Q000378:metabolism; D009414:Nerve Growth Factors / Q000096:biosynthesis* / Q000494:pharmacology* / Q000502:physiology; D010544:Peroxidases / Q000097:blood; D012333:RNA, Messenger / Q000378:metabolism
D015850:Interleukin-6; D009414:Nerve Growth Factors; D012333:RNA, Messenger; D047209:Eosinophil Peroxidase; D010544:Peroxidases