Positional expression profiling map showing relative expression of MHC class II genes and those genes physically located telomeric, within, and centromeric to the MHC class II loci. Color coding is used to indicate the relative expression of genes. Each row indicates one of the MHC class II^- cases by individual patient study number. The last 9 rows are activated B cells (ABC; with hours of activation indicated) and germinal center B cells (GCB). tot indicates total from a normal lymph node; Cbl, centroblastic cells from healthy individuals; and Ccyte, centrocytes from healthy individuals. MHC class II genes are indicated with dots. Gene expression (e) is colored as follows: dark blue, e < -2; medium blue, -2 ≤ e < -1; light blue, -1 ≤ e < 0; yellow, 0 ≤ e < 1; orange, 1 ≤ e < 2; red, e ≥ 2; and light gray, no value.