CD4 T cell counts showed no statistical differences among the four groups (IPF: 614.8 ± 469; CVD: 711.8 ± 431.1; CB/pneumonia: 403.3 ± 369.9; and PCP: 129 ± 96.7) (Figs. 3a, b). This evidence concerns the gene CD4 and susceptibility to pneumonia measurement.