Human eosinophils synthesize and secrete interleukin-6, in vitro.
Using the technique of in situ hybridization, we have shown that resting, unstimulated, human peripheral blood eosinophils, obtained from subjects with greater than 8% eosinophilia, transcribe and translate messenger RNA (mRNA) for interleukin-6 (IL-6). After incubation for 24 hours in culture medium alone, approximately 19% of eosinophils were positive for IL-6 mRNA. This may be a reflection of their in vivo activation, but also may suggest that the gene for this cytokine is constitutively expressed in eosinophils. After stimulation with interferon gamma (IFN gamma) (500 U/mL), the percentage of IL-6-mRNA+ cells increased to 51.3%. This was accompanied by an enhancement of intensity of the hybridization signals. The specificity of the IL-6 probe and the hybridization signals was confirmed by the use of an IL-6 sense probe and RNase pretreatment of cell preparations. Evidence for the translation of IL-6 mRNA was obtained by immunocytochemical staining. Normal and activated eosinophils gave IL-6-specific immunoreactivity with a polyclonal antihuman IL-6 antibody. A higher percentage of positive cells was detected among activated eosinophils than those treated with medium alone. Using a specific immunoenzymetric assay, we detected 190.15 +/- 18.1 and 403.32 +/- 213.6 pg/mL of IL-6 in supernatants of unstimulated and IFN gamma-treated (24 and 48 hours) eosinophils, respectively. These data indicate that eosinophils are an important cellular source of IL-6.
Hamid
Q
Q
Department of Allergy and Clinical Immunology, National Heart & Lung Institute, London, UK.
Barkans
J
J
Meng
Q
Q
Ying
S
S
Abrams
J S
JS
Kay
A B
AB
Moqbel
R
R
D000906:Antibodies / Q000032:analysis; D004804:Eosinophils / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D007124:Immunoenzyme Techniques; D007371:Interferon-gamma / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008832:Microchemistry; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000032:analysis; D014158:Transcription, Genetic
D000906:Antibodies; D015850:Interleukin-6; D012333:RNA, Messenger; D007371:Interferon-gamma