Differentiation between idiopathic pulmonary fibrosis and interstitial pneumonia associated with collagen vascular diseases by comparison of the ratio of OKT4+ cells and OKT8+ cells in BALF T lymphocytes.

Idiopathic pulmonary fibrosis (IPF) and interstitial pneumonia associated with collagen vascular disease have been shown to be difficult to differentiate by clinical, roentgenological, pathological and immunological findings. We have applied the analysis of BALF T cell phenotypes to these two groups by enumerating the cell populations of OKT4+ and OKT8+ cells in BALF and, as a result, have been able to discern a clear and meaningful differentiating point between the two groups. In all 9 patients with IPF were examined in whom OKT4+ cells outnumbered OKT8+ cells in BALF T cell subsets, while 13 patients with collagen vascular disease were tested (3 SLE, 6 RA, 2 Sjögren's syndrom and 2 MCTD) in whom OKT8+ cells were more numerous than OKT4+ cells. No difference was observed in blood T lymphocytes between these two groups. These results provide us with a means of differentiation between these groups, especially in clinically borderline cases.