Culture of PBL results in upregulation of FasL mRNA, which is inhibited by E64d. (A) Mean FasL mRNA levels ± standard error of mean (SEM) in fresh PBL and PBL cultured for 20 hours in the absence or presence of E64d from uninfected (n = 6) and HIV-infected (n = 9) individuals. (B) Competitive PCR analysis of actin cDNA from HIV⁺ PBL (n = 4). Data are expressed as the arithmetic mean ± SEM.