CD4 and acute respiratory distress syndrome: In lung parenchyma analysis, there was a significantly higher expression of CD8+ T cells (Fig. 3 a, b, c, d), CD4+ T cells (Fig. 3 e, f, g, h), and CD83+ cells (Fig. 3 h, i, j, k) in the H1N1 group compared to the ARDS and Control groups.