MUM1/IRF4 expression in the circulating compartment of chronic lymphocytic leukemia.
MUM1/IRF4 is normally expressed in late germinal center/post germinal center B-cells. Previous studies of chronic lymphocytic leukemia in bone marrow and lymph node have demonstrated variable expression of MUM1/IRF4 and conflicting prognostic significance. In this study we evaluated MUM1/IRF4 expression in peripheral blood CLL cells utilizing Histogel cell blocks. MUM1/IRF4 was absent in 4/36 (11%) specimens. The remaining cases demonstrated variable intensity and proportion of positive cells: <20% positive 16/36 (44%), 20 - 50% positive 12/36 (33%), >50% 4/36 (11%). No correlation was identified between MUM1/IRF4 and percent of CD38 positive cells, CD38 status (+/-), ZAP-70 status (+/-), and IgVH mutational status. The variability in MUM1/IRF4 staining suggests a level of biologic complexity that is not adequately reflected in the current binary models of CLL pathobiology. This heterogeneity may reflect the role of MUM1/IRF4 as an effector and integrator of several lymphocyte activation pathways including antigenic and environmental stimuli.
Craig
Fiona
F
Division of Hematopathology, Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. craigfe@upmc.edu
Soma
Lorinda
L
Melan
Melissa
M
Kant
Jeffrey
J
Swerdlow
Steven
S
D051997:ADP-ribosyl Cyclase 1 / Q000032:analysis; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007150:Immunohistochemistry; D050835:Interferon Regulatory Factors / Q000032:analysis*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000473:pathology*; D008198:Lymph Nodes / Q000737:chemistry; D014066:Palatine Tonsil / Q000737:chemistry; D015203:Reproducibility of Results; D051746:ZAP-70 Protein-Tyrosine Kinase / Q000032:analysis; D000099218:Interferon Regulatory Factor-4
D051997:ADP-ribosyl Cyclase 1; D007143:Immunoglobulin Heavy Chains; D050835:Interferon Regulatory Factors; D051746:ZAP-70 Protein-Tyrosine Kinase; D000099218:Interferon Regulatory Factor-4; C497261:ZAP70 protein, human