We used antibodies coupled to magnetic beads (MACS) to purify cell types out of whole blood from healthy donors (CD4+ T cells, CD8+ T cells, and B cells). We also profiled whole blood (collected in Pax tubes) and Peripheral Blood Mononuclear cells obtained by Ficoll-Paque based separation. RNA was extracted using Trizol, amplified linearly twice, labeled with Cy5 and co-hybridized with amplified Stratagene human reference (labeled with Cy3). A reference experiement design type is where all samples are compared to a common reference. Using regression correlation