In this study, the Interleukin-2 receptor (IL-2R) and lymphocyte subsets in the patients with idiopathic interstitial pneumonia (IIP), interstitial pneumonia with collagen vascular disease (IPCVD) and alveolar type of HTLV-I associated bronchiolo-alveolar disorder (HABA-A) were evaluated. Soluble IL-2R (sIL-2R) in the lymphocyte culture supernatant increased in IIP, while the sIL-2R in sera and IL-2R positive lymphocyte showed no increase. In HABA-A, the serum sIL-2R level, the responsiveness to IL-2 and percentage of IL-2R positive lymphocytes and helper-T lymphocytes were increased. In IPCVD, the serum sIL-2R level increased but the percentage of IL-2R positive lymphocytes and helper-T lymphocytes decreased. The CD4/CD8 ratio was low in IIP and IPCVD, but high in HABA-A. In patients with IIP or IPCVD treated with steroids, the percentage of IL-2R positive lymphocytes and helper-T lymphocytes decreased more than in those not treated with steroids. Therefore, cellular immunity regulated by the IL-2 and IL-2R system might play an important role in the pathogenesis of IPCVD and HABA-A.
soluble interleukin-2 receptor