CD4 and acute respiratory distress syndrome: Non-survivors were predominantly males (p = 0.023) with more ARDS (p = 0.01) and requiring more mechanical ventilation (p < 0.001); they had more activated CD4+ T-cells (p = 0.019), higher IL-6 levels (p = 0.005) and a lower lymphocyte count with lower neutrophil-lymphocyte and lymphocyte-monocyte ratios (Table 1).