Reproducibility and integrity of cell type preparations. (A) Processed gene expression data of 8 separated cell types and of whole blood was visualized in a dimension reduction method, principal component analysis (PCA). Signal intensities from all 18898 probes separate cell types lead to a separation of cell types. T-cells (CD3+, CD4+ and CD8+) form one cluster which separates well from the B-cells (CD14+, CD15+, CD19+, CD45+, CD56+) or full blood. Each sphere represents a single sample. The x- and the y-axis (principal components 1 and 2, respectively) are labeled. The z-axis is not labled for graphical reasons. (B) Unsupervised hierarchical cluster analysis, same samples and gene list as in (A). Cluster was generated with Euclidean distance and Ward’s method. Only sample dendrogram is shown. CD3+, CD4+, and CD8+ are grouped as “T cells”.