A – Clusterogram of genes coding for immune effector molecules including lymphokines, lytic granules and TNF family members. Only genes whose expression is significantly altered by rIL-2 (paired t test p2-value < 0.001) are shown. Light blue and red horizontal bares underline PBMC sample from Caucasian and Chinese donors; in separate panels CD4 (small red horizontal bar) and CD8 T cells (light blue bar) exposed to rIL-2 in the presence of PBMC and subsequently isolated are compared with CD4 and CD8 T cells (orange and dark blue horizontal bars respectively) purified before exposure to rIL-2. Four predominant nodes are underlined: node a) included genes down-regulated by rIL-2; node b) enriched with genes associated with lytic pathways; node c) enriched with cytokine genes and associated NF-k B pathways and node d) including a less characteristic mixture of genes. Horizontal blue bars above the clusterogram denote Caucasian and horizontal red bars Chinese subjects. Ratios are displayed according to the central method for display using a normalization factor . B – Cartoon postulating the effector pathways affected by rIL-2 treatment; in light blue are genes whose expression is down regulated and in red genes whose expression is up-regulated. In dark blue are presented genes whose expression is not significantly affected by rIL-2. This cartoon represents an oversimplification of the various pathways and we refer the reader to the text for further details.