Figure 1.

CD4⁺ naïve and memory CD27⁺ and CD27⁻ cells were co-cultured with irradiated autologous peripheral blood mononuclear cells (PBMC) and stimulated with medium (white bar) or one of four different antigens (black bar): (a) tetanus toxoid; (b) streptokinase C; (c) Candida enolase; or (d) lipase. The total incubation time was 8 days. The average of four replicate cultures ± standard deviation is shown, and the data are representative of two to four experiments. Statistical analysis was performed by analysis of variance (anova) (**P < 0·01; ***P < 0·001). c.p.m., counts per minute.