Bone marrow aspirates from 306 patients with multiple myeloma were analyzed by flow cytometric immunophenotyping. The plasma cells (PCs) were identified by their characteristic light scatter distribution and reactivity patterns to CD138, CD38, and CD45. Monoclonality was confirmed by immunoglobulin light chain analysis. The immunophenotypic profile of the PCs was determined with a panel of antibodies. Moderate to bright expression of CD56, CD117, CD20, CD45, and CD52 was detected in 71.7%, 17.8%, 9.3%, 8.8%, and 5.2% of cases, respectively. These antigens were expressed by a distinct subpopulation of the PCs in 6.3%, 2.2%, 3.7%, 2.9%, and 2.6% of additional cases. CD19 was negative in more than 99% of cases. The combination of CD38 and CD138 was superior to CD38 alone for identifying CD45+ myeloma and separating CD20+ myeloma from B-cell lymphoma. PC immunophenotyping might be useful for detecting minimal residual disease in cases with aberrant antigen expression and for selection of therapeutic agents that have specific membrane targets.

Bone marrow aspirates from 306 patients with multiple myeloma were analyzed by flow cytometric immunophenotyping. The plasma cells (PCs) were identified by their characteristic light scatter distribution and reactivity patterns to CD138, CD38, and CD45. Monoclonality was confirmed by immunoglobulin light chain analysis. The immunophenotypic profile of the PCs was determined with a panel of antibodies. Moderate to bright expression of CD56, CD117, CD20, CD45, and CD52 was detected in 71.7%, 17.8%, 9.3%, 8.8%, and 5.2% of cases, respectively. These antigens were expressed by a distinct subpopulation of the PCs in 6.3%, 2.2%, 3.7%, 2.9%, and 2.6% of additional cases. CD19 was negative in more than 99% of cases. The combination of CD38 and CD138 was superior to CD38 alone for identifying CD45+ myeloma and separating CD20+ myeloma from B-cell lymphoma. PC immunophenotyping might be useful for detecting minimal residual disease in cases with aberrant antigen expression and for selection of therapeutic agents that have specific membrane targets.

Syndecan-1 (CD138) mediates myeloma cell adhesion, and loss of syndecan-1 from the cell surface may contribute to myeloma proliferation and dissemination. Flow cytometry analysis of myeloma cells in bone marrow specimens shows heterogeneity in cell surface syndecan-1 expression. It is not known whether weaker expression correlates with more aggressive disease. However, recent reports suggest that variations in syndecan-1 staining intensity on myeloma cells may be an artifact of specimen handling. In this study, we evaluate syndecan-1 expression in bone marrow biopsy sections from 28 multiple myeloma patients, to elucidate the heterogeneity of syndecan-1 expression in situ. Immunoreactivity for syndecan-1, using the antibody B-B4 (CD138), was found in more than 95% of multiple myeloma cells in 27 of 28 biopsies. However, one biopsy had more than 50% CD138-negative cells and cells with weak CD138 expression were identified in the majority of cases. Loss of syndecan-1 did not appear to relate to myeloma cell differentiation. In addition, syndecan-1 was detected on intravascular and intrasinusoidal myeloma cells suggesting that loss of syndecan-1 may not be required for extramedullary dissemination. Bone marrow biopsies from nine additional patients, with variable CD138 staining intensity on myeloma cells as determined by flow cytometry, were studied by immunohistochemistry. The heterogenous CD138 expression was confirmed in situ, with weakly positive cells concentrated in areas of reticulin fibrosis. These cells had a disrupted pattern of membrane staining in contrast to the strong linear membrane staining seen in the other multiple myeloma cells. In addition, the fibrotic stroma stained intensely for syndecan-1. Accumulation of syndecan-1 within the extracellular matrix of the marrow likely is derived by shedding of the molecule from the surface of myeloma cells. Because syndecan-1 can act to regulate the activity of heparan-binding growth factors, these reservoirs of syndecan-1 may play a critical role in promoting myeloma pathogenesis, or in regeneration of the tumor after chemotherapy.

The membrane glycoprotein MRC OX-2 (CD200) is expressed in several lymphoid malignancies. However, the diagnostic utility and potential prognostic importance of CD200 expression have not been rigorously examined. We show that CD200 is uniformly expressed in chronic lymphocytic leukemia (CLL) and absent in mantle cell lymphoma (MCL). Importantly, expression of CD200 is retained even in those CLLs with immunophenotypic aberrancies, making CD200 a particularly useful marker for discrimination between these cases and MCL. CD200 is expressed in nearly all precursor B lymphoblastic leukemias, with aberrant over- or underexpression when compared to normal B-cell progenitors in 55% of cases. Over 70% of plasma cell myelomas (PCMs) expressed CD200, and loss of CD200 expression in PCM may be associated with more clinically aggressive disease. In summary, CD200 is expressed in several hematolymphoid neoplasms. Analysis of its expression has several diagnostic, and potentially prognostic, applications in the flow cytometric evaluation of lymphoid malignancies.

ObjectivesTo determine whether local trainer-led TARGET antibiotic interactive workshops improve antibiotic dispensing in general practice.MethodsUsing a McNulty–Zelen-design randomized controlled trial within three regions of England, 152 general practices were stratified by clinical commissioning group, antibiotic dispensing rate and practice patient list size, then randomly allocated to intervention (offered TARGET workshop that incorporated a presentation, reflection on antibiotic data, promotion of patient and general practice (GP) staff resources, clinical scenarios and action planning, 73 practices) or control (usual practice, 79 practices). The primary outcome measure was total oral antibiotic items dispensed/1000 patients for the year after the workshop (or pseudo-workshop date for controls), adjusted for the previous year’s dispensing.ResultsThirty-six (51%) intervention practices (166 GPs, 51 nurses and 101 other staff) accepted a TARGET workshop invitation. In the ITT analysis total antibiotic dispensing was 2.7% lower in intervention practices (95% CI −5.5% to 1%, P = 0.06) compared with controls. Dispensing in intervention practices was 4.4% lower for amoxicillin/ampicillin (95% CI 0.6%–8%, P = 0.02); 5.6% lower for trimethoprim (95% CI 0.7%–10.2%, P = 0.03); and a non-significant 7.1% higher for nitrofurantoin (95% CI −0.03 to 15%, P = 0.06). The Complier Average Causal Effect (CACE) analysis, which estimates impact in those that comply with assigned intervention, indicated 6.1% (95% CI 0.2%–11.7%, P = 0.04) lower total antibiotic dispensing in intervention practices and 11% (95% CI 1.6%–19.5%, P = 0.02) lower trimethoprim dispensing.ConclusionsThis study within usual service provision found that TARGET antibiotic workshops can help improve antibiotic use, and therefore should be considered as part of any national antimicrobial stewardship initiatives. Additional local facilitation will be needed to encourage all general practices to participate.