When we divided the patients according to T and B cell subsets, we found that pneumonia was statistically more frequent in patients with low CD3+ (16/39, 41% vs 2/24, 8.3%, P = 0.0085) and CD4+ (17/43, 39.5% vs 1/18, 5.5%, P = 0.012) T cells. This evidence concerns the gene CD4 and pneumonia.