CEACAM expression in MM. (A) Expression of CEACAM-mRNA in CD138+ purified plasma cells from BM of myeloma patients (MM, n = 332) or healthy subjects (HD, n = 10), as determined by Affymetrix GeneChip arrays. Blue dots indicate expression; red indicates lack of expression as determined by the PANP-algorithm (see “Materials and methods”). (B) Percentages of samples expressing the respective CEACAMs in (A). (C-E) Expression of CEACAM protein on CD138+ myeloma cells from BM of MM patients on plasma cells from healthy subjects and on myeloma cell lines RPMI8226 and SKMM2, as determined by flow cytometry. (C) Dot plots showing expressions of CD138 and CEACAMs on BM cells from 1 MM patient. (D) Cumulative proportions of CEACAM-expressing CD138+ cells from BM of MM patients (black bars) or healthy individuals (white bars). (E) Gray histograms demonstrate CEACAM expression on gated CD138+ cells from myeloma cell lines RPMI8226 and SKMM2. Proportions of CEACAM-positive cells are shown as percentages (%). Negative controls are shown as white histograms. *Significant difference between patients and healthy donors (P < .05, 2-sided Student t test).