To investigate the allergen-induced messenger RNA (mRNA) expression of interleukin (IL) 4, IL-5 and interferon gamma (IFN-γ) in peripheral blood mononuclear cells from individuals sensitized by Japanese cedar (Cryptomeria japonica) pollens, and to elucidate the clinical role of IL-4, IL-5, and IFN-γ in the allergen sensitization and clinical manifestation of allergic disorders.
This study included 30 patients sensitized to the pollen and 14 nonatopic healthy volunteers. Peripheral blood mononuclear cells (1.0 × 106 cells/mL) of each individual were cultured at 37°C for 24 hours in the presence of 10 µg/mL of Cry j 1, a major allergen of the pollens. Total cellular RNA was extracted from the peripheral blood mononuclear cells, and IL-4, IL-5, and IFN-γ mRNA expression was determined with a reverse transcriptase polymerase chain reaction.
From the results of a survey of symptom diary cards and interviews regarding nasal symptoms during the pollen season in 1998, we found that 20 patients (symptomatic group), but not 10 patients (asymptomatic group), had typical symptoms of seasonal allergic rhinitis. Interleukin 4 mRNA was not expressed in the nonatopic subjects but was expressed in 9 asymptomatic patients and in 17 symptomatic patients. Interleukin 5 mRNA was exclusively expressed in the symptomatic patients. Interferon γ mRNA expression did not differ significantly among the nonatopic subjects, asymptomatic patients, and symptomatic patients.
This study has clearly highlighted an interesting and new concept that IL-4 is implicated in allergen sensitization but not in clinical manifestation, and that IL-5 may not be a feature of atopy in itself but seems to be a hallmark of clinical manifestation of ongoing atopic diseases.