title: Natural production and functional effects of alternatively spliced interleukin-4 protein in asthma.
abstract: We have previously described an alternatively spliced isoform of IL-4 mRNA that omits exon 2 and is termed IL-4δ2. However, the natural production of IL-4δ2 protein and its association with disease have not been previously assessed due to unavailability of an antibody that interacts with IL-4δ2 without cross-reactivity with full length IL-4. We used a unique monoclonal antibody (mAb) that reacts with IL-4δ2, but not with IL-4, and observed that IL-4δ2 is naturally produced by T cells from patients with asthma, but not from healthy controls. The kinetics of IL-4δ2 and IL-4 production by phorbol myristate acetate (PMA)/ionomycin-activated cells differed, with IL-4δ2 increasing at 48-72h and IL-4 peaking at 24h. The steady-state levels of IL-4δ2 mRNA varied significantly among the donors and were discordant with the corresponding protein levels, suggesting post-transcriptional regulation of protein production. Polarized Th1 or Th2 lymphocytes were not a major source of IL-4δ2. Stimulation of cultured T lymphocytes with IL-4δ2 caused elevated production of IFN-γ, IL-10, IL-6, MCP-1, and TNF-α, with notable differences between patients and controls in the production of IFN-γ, IL-10, and IL-6. Thus, IL-4δ2 is natively produced not only as mRNA but also as a protein by cells other than Th1 or Th2. It is regulated post-transcriptionally, is associated with allergic asthma, and regulates production of other cytokines by primary T lymphocytes. Alternatively spliced interleukin-4 may be a new biomarker, a pathophysiological player, and possibly a molecular target for future therapies in asthma.
authors.affiliation: Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Irina G
authors.initials: IG
authors.lastname: Luzina
authors.forename: Virginia
authors.initials: V
authors.lastname: Lockatell
authors.forename: Sachin
authors.initials: S
authors.lastname: Lavania
authors.forename: Edward M
authors.initials: EM
authors.lastname: Pickering
authors.forename: Phillip H
authors.initials: PH
authors.lastname: Kang
authors.forename: Yulia N
authors.initials: YN
authors.lastname: Bashkatova
authors.forename: Sergey M
authors.initials: SM
authors.lastname: Andreev
authors.forename: Sergei P
authors.initials: SP
authors.lastname: Atamas
mesh_terms: D000328:Adult; D017398:Alternative Splicing; D001249:Asthma / Q000235:genetics* / Q000503:physiopathology*; D006801:Humans; D015847:Interleukin-4 / Q000096:biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*
chemical_list: C508598:IL4 protein, human; D012333:RNA, Messenger; D015847:Interleukin-4