CD4 and severe acute respiratory syndrome: At 60 days, compared to normal subjects, there was a significant increase in total cell counts in BAL fluid from SARS patients (Table 3) with a significant increase in alveolar macrophages (AM) and lymphocytes., The proportion of CD8+ T cells was increased to a greater extent than CD4+ T cells, leading to a significant decrease in CD4/CD8 ratio (Table 4).