Interleukin 6 and interferon-γ gene expression in lung transplant recipients with refractory acute cellular rejection: Implications for monitoring and inhibitory by treatment with aerosolized cyclosporine

Background. The purpose of this study was to correlate cytokine gene expression from bronchoalveolar lavage (BAL) cells and peripheral blood lymphocytes (PBL) with graft histology in recipients with persistent acute rejection treated with aerosolized cyclosporine (ACsA). Methods. We measured mRNA for interleukin (IL) 6, interferon (IFN)-γ and IL-10 in recipients (1) without rejection (n=13), (2) with acute rejection that responded to pulsed methylprednisolone (n=7), and (3) with 'refractory' acute rejection that failed to respond to conventional immunosuppression (n=17). In the latter group, ACsA was initiated. Results. Bal cell IL-6 and IFN-γ were highest in recipients with refractory rejection compared with recipients with steroid- responsive rejection and recipients with no rejection. Improvement in rejection histology occurred in 15 of 17 recipients who were treated with ACsA. IL-6 and IFN-γ mrna levels from Bal cells decreased during treatment with ACsa (median IL-6:actin ratio: before treatment, 0.40 vs. after treatment, 0.003, P=0.001; IFN-γ:actin ratio: before treatment, 0.32 vs. after treatment, 0.04, P=0.001), PBL IL-6 and IFN-γ mRNA expression also decreased during ACsA treatment after 180 days. Expression of IL-10 mRNA from BAL and PBL did not change during ACsA treatment (0.0 vs. 0.03 and 0.0 vs. 0.02, respectively). Conclusions. IL-6 and IFN-γ mRNA expression from BAL cells was highest in those recipients with refractory histologic acute rejection. ACsA was associated with decreased IFN-γ and IL-6 gene expression in BAL cells and PBL.