Effect of interferon-gamma on HLA class 2 expression by antigen-presenting cells inducing Dermatophagoides farinae-specific interleukin-2 responsiveness of lymphocytes in asthmatic children.

As previously reported, antigen-specific IL-2 responsiveness of lymphocytes from patients with bronchial asthma was induced by stimulation with Dermatophagoides farinae, antigen-specifically, in the context of HLA-DQ antigen. We analysed the antigen-presenting processes in the induction of IL-2 responsiveness. Non-adherent responder cells cultured with Df-pulsed autologous adherent cells acquired IL-2 responsiveness, which decreased after prolonged culture of adherent cells for 72 h before recombination with fresh autologous non-adherent cells. HLA-DQ expression on cultured adherent cells also decreased in parallel with the reduction of their ability to induce IL-2 responsiveness. However, the treatment of adherent cells with IFN-gamma restored the expression of these HLA-Class 2 antigens mainly on CD14+ antigen-presenting cells (monocytes), but not on CD20+ cells (B cells), which overcame the decrease of Df-induced IL-2 responsiveness during prolonged culture. These data suggest that IFN-gamma potentiates the up-regulation of Df-specific IL-2 responsiveness, which is likely to depend on the restoration of HLA-DQ expression on monocytes.