At the 20th day after illness onset, the dynamic curves of neutrophil proportion, CD4+ T lymphocyte count, and the levels of CRP, ESR, IL-6, and procalcitonin between patients with pneumonia and those without tended to meet (P > 0.05); however, the two curves of CD8+ T lymphocyte counts kept separated (P < 0.05) (Figs. 1 and 2). Here, CD4 is linked to susceptibility to pneumonia measurement.