CD10 and MUM1 are representative B cell differentiation markers. Follicular lymphoma (FL) is usually positive for CD10 and negative for MUM1. In this study, however, we compared 22 FLs with peculiar phenotype CD10 ؊ MUM1 ؉ with 119 typical CD10 ؉ MUM1 ؊ FLs. All CD10 ؊ MUM1 ؉ FL patients exhibited follicular structure with follicular dendritic meshwork, and a high rate of somatic hypermutation and ongoing mutation, similar to typical FL. However, CD10 ؊ MUM1 ؉ FLs were encountered frequently in the elderly compared with CD10 ؉ MUM1 ؊ typical FLs (67.0 versus 58.7 years, P < .01), showed high grade (grade 3A or 3B) morphology (91% versus 17%, P < .001), diffuse proliferation (59% vs 19%, P < .001), and lacked BCL2/IGH translocation (5% versus 92.5%, P < .001), which is the most characteristic aberration in FL, and 88% showed BCL6 gene abnormalities (translocation or amplification IntroductionFollicular lymphoma (FL) is the most prevalent form of low-grade B-cell lymphoma in adults. 1 Typically, FL cells express CD10, BCL2, and BCL6. CD10 is a marker for germinal center (GC) B cells, and thus its expression suggests that GC B cells are a normal counterpart of FL. 2 However, some reports, including our previous study, described the existence of CD10 Ϫ FL, especially in high-grade (grade 3) FL. [3][4][5][6] However, it is not clear whether CD10 negativity is just aberrant loss or whether it is meaningful, reflecting a specific differentiation stage and affecting clinical features. MUM1 (multiple myeloma oncogene 1)/IRF4 (interferon regulatory factor 4) is a lymphoid-specific member of the interferon regulatory factor family of transcription factors, 7-9 and it is a reliable marker of "late-stage GC" or "post-GC" B cells. 8 In this study, we clinicopathologically compared CD10 Ϫ MUM ϩ and "classical" CD10 ϩ MUM1 Ϫ FLs. Materials and methods Biologic materialTissue specimens were obtained from human lymph nodes filed at the Department of Pathology at Fukuoka University and Kurume University. The 147 FL patients have already been reported in our previous publication. 5 Paraffin-embedded tissues were available in almost all patients, while frozen tissues and cell suspensions were available in some patients. Histopathological diagnoses and grading were based on the new WHO classification and carried out by 4 pathologists (Y.G., K.K., M.K., and K.O.). 1 Clinical information was obtained by reviewing the tumor registry records and/or patients' medical charts. This study was approved by the Kurume University institutional review board (Kurume, Japan), and patients provided informed consent in accordance with the Declaration of Helsinki. ImmunohistochemistryParaffin sections from each sample were immunostained with monoclonal antibodies against CD10 (Novocastra, Newcastle, United Kingdom), Bcl2 (DAKO, Glostrup, Denmark), MUM1 (DAKO), CD21 (DAKO), CD138 (Novocastra), and Bcl6 (Novocastra) following the method described previously. 5 The following 2 categories were defined: negative (Ͻ 30% positively-stained tumor cells) and ...

ObjectivesThe main histological change in rheumatoid arthritis (RA) is the villous proliferation of synovial lining cells, an important source of cytokines and chemokines, which are associated with inflammation. The aim of this study was to evaluate gene expression in the microdissected synovial lining cells of RA patients, using those of osteoarthritis (OA) patients as the control.MethodsSamples were obtained during total joint replacement from 11 RA and five OA patients. Total RNA from the synovial lining cells was derived from selected specimens by laser microdissection (LMD) for subsequent cDNA microarray analysis. In addition, the expression of significant genes was confirmed immunohistochemically.ResultsThe 14 519 genes detected by cDNA microarray were used to compare gene expression levels in synovial lining cells from RA with those from OA patients. Cluster analysis indicated that RA cells, including low- and high-expression subgroups, and OA cells were stored in two main clusters. The molecular activity of RA was statistically consistent with its clinical and histological activity. Expression levels of signal transducer and activator of transcription 1 (STAT1), interferon regulatory factor 1 (IRF1), and the chemokines CXCL9, CXCL10, and CCL5 were statistically significantly higher in the synovium of RA than in that of OA. Immunohistochemically, the lining synovium of RA, but not that of OA, clearly expressed STAT1, IRF1, and chemokines, as was seen in microarray analysis combined with LMD.ConclusionsOur findings indicate an important role for lining synovial cells in the inflammatory and proliferative processes of RA. Further understanding of the local signalling in structural components is important in rheumatology.

Although various CD markers have been analyzed in T-cell and natural killer (NK)-cell lymphomas, the sensitivity and specificity of these phenotypic features have not been satisfactorily characterized. Flow cytometry (FCM) was used to determine the phenotypic pattern of 490 T/NK-cell lymphomas with the aid of a set of surface antigens (CD2, CD3, CD4, CD5, CD7, CD8, CD10, CD11c, CD16, CD19, CD20, CD25, CD30, CD34, and CD56). In data obtained from 319 patients, CD10 expression was detected in 57% of angioimmunoblastic T-cell lymphomas, CD30 in 93% of anaplastic large cell lymphomas, CD34 in 50% of lymphoblastic lymphomas, and CD56 in 100% of extranodal NK/T-cell lymphomas nasal type. A total of 92% of adult T-cell leukemia/lymphomas (ATLL) had expression of CD25 and downregulation of CD7. Of special interest is that 92 ATLL (50%) were CD4+CD7-CD25+ phenotype while only four peripheral T-cell lymphoma unspecified (9%) and one (9%) cutaneous T-cell lymphoma had this phenotype. Phenotypic analysis using FCM was thus found to be useful for differential diagnosis of T-cell and NK-cell lymphomas.

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