TCRζ expression in PBLs from healthy donors. (A) PBLs were analyzed for expression of TCRζ and CD3 by flow cytometry. Four donors illustrating the heterogeneity of TCRζ expression are shown. (B) PBLs were stained for TCRζ and CD3 expression. CD45RA and CD45RO expression on TCRζ^bright and TCRζ^dim subsets were then determined by flow cytometry. (C) The percent CD45RA⁺ or CD45RO⁺ cells residing within TCRζ^bright and TCRζ^dim subsets were analyzed for 10 or 12 healthy donors, respectively. Horizontal lines represent mean values.