[In situ hybridization for interleukin 4 and interleukin 5 messenger RNA in asthma]

The actual mechanism by which a group of asthmatics were resistant to glucocorticoids therapy remains poorly understood. Previous in vitro studies suggested that the pattern of cytokine gene expression may play a role in determining steroid resistance. In the current study, we used the technique of mRNA in situ hybridization to examine whether peripheral blood mononuclear cells (PBMCs) from steroid-resistance (SR) asthmatics vs. Steroid-sensitive (SS) asthmatics expressed different patterns of cytokines, particularly after treatment with steroid. PBMCs from SR patients did not differ significantly from those of SS in terms of their number expressing Interleukin (IL)-4 mRNA and IL-5 mRNA (P > 0.05) by culture alone. There were no differences in the number of PBMCs expressing IL-4 mRNA and IL-5 mRNA (P > 0.05) between incubation in the absence and presence of dexamethasone (DXM, 10(-7) mol/L) in SR. SS patients had a significant dicrease in the number of PBMCs expressing IL-4 mRNA and IL-5 mRNA (P < 0.01) after culture in the presence of DXM as compared with incubation in media alone. Our findings indicate that SR asthma is associated with a dysregulation of the expression of the genes encoding for IL-4 and IL-5.