This finding correlated with reduced CD8+ T lymphocyte counts observed in HP patients with fibrosis (11.65 ± 2.8% vs. 23.6 ± 2.9%, p = 0.008) and in those who died during follow-up (10.0 ± 1.9% vs. 23.8 ± 2.7%, p = 0.012), suggesting a protective role for CD8+ T cells (Figure 6). Here, CD8A is linked to hypersensitivity pneumonitis.