(A) Serum levels of soluble FasL and (B) CD4 counts from 6 HIV-infected individuals evaluated at different stages of the disease. Each symbol represents the values from one subject examined during the asymptomatic period and then 2 to 7 years later, during the symptomatic/AIDS stage. Statistically significant decrease in serum FasL (P = .0431; Wilcoxon matched-pairs test) and CD4 counts (P = .0464) was noted with disease progression.