Background: Major heterogeneity between laboratories in flow cytometry (FC) minimal residual disease (MRD) testing in multiple myeloma (MM) must be overcome. Cytometry societies such as the International Clinical Cytometry Society and the European Society for Clinical Cell Analysis recognize a strong need to establish minimally acceptable requirements and recommendations to perform such complex testing.Methods: A group of 11 flow cytometrists currently performing FC testing in MM using different instrumentation, panel designs ( 6-color) and analysis software compared the procedures between their respective laboratories and reviewed the literature to propose a consensus guideline on flow-MRD analysis and reporting in MM.Results/Conclusion: Consensus guidelines support i) the use of minimum of five initial gating parameters (CD38, CD138, CD45, forward, and sideward light scatter) within the same aliquot for accurate identification of the total plasma cell compartment; ii) the analysis of potentially aberrant phenotypic markers and to report the antigen expression pattern on neoplastic plasma cells as being reduced, normal or increased, when compared to a normal reference plasma cell immunophenotype (obtained using the same instrument and parameters); and iii) the percentage of total bone marrow plasma cells plus the percentages of both normal and neoplastic plasma cells within the total bone marrow plasma cell compartment, and over total bone marrow cells. Consensus guidelines on minimal current and future MRD analyses should target a lower limit of detection of 0.001%, and ideally a limit of quantification of 0.001%, which requires at least 3 3 10 6 and 5 3 10 6 bone marrow cells to be measured, respectively. V C 2015 International Clinical Cytometry Society

Immunophenotyping by flow cytometry has become standard practice in the evaluation and monitoring of patients with hematopoietic neoplasia. However, despite its widespread use, considerable variability continues to exist in the reagents used for evaluation and the format in which results are reported. As part of the 2006 Bethesda Consensus conference, a committee was formed to attempt to define a consensus set of reagents suitable for general use in the diagnosis and monitoring of hematopoietic neoplasms. The committee included laboratory professionals from private, public, and university hospitals as well as large reference laboratories that routinely operate clinical flow cytometry laboratories with an emphasis on lymphoma and leukemia immunophenotyping. A survey of participants successfully identified the cell lineage(s) to be evaluated for each of a variety of specific medical indications and defined a set of consensus reagents suitable for the initial evaluation of each cell lineage. Elements to be included in the reporting of clinical flow cytometric results for leukemia and lymphoma evaluation were also refined and are comprehensively listed. The 2006 Bethesda Consensus conference represents the first successful attempt to define a set of consensus reagents suitable for the initial evaluation of hematopoietic neoplasia. q 2007 Clinical Cytometry Society

BACKGROUND: The WHO and iwCLL diagnostic criteria for CLL rely on morphology and immunophenotype based on the co-expression of CD19/CD5/CD23 on B-cells with weak CD20 and monoclonal sIg expression. These diagnostic criteria are likely to persist in the near future because there is no specific diagnostic molecular abnormality for CLL. The current criteria have some limitations affecting reproducibility, particularly flexibility in marker expression with many centres using a scoring system that permits absence of CD5 or CD23. Potentially informative new markers have been identified but there is no consensus yet on which should be routinely assessed. AIM: To identify reproducible criteria and to achieve a consensus on markers recommended for the diagnosis of CLL METHODS: ERIC/ESCCA members were invited to classify 35 flow-cytometry markers as being required or recommended for the diagnosis of CLL. Consensus was considered to be achieved if >75% of participants agreed on the marker classification. A diagnostic panel was identified by the steering committee and characteristics of component markers that could be reproducibly validated within an individual laboratory were identified. The proposed panel was assessed in 13 different centres. RESULTS: Responses were received from 154 members (100 laboratory staff, 14 clinicians and 36 from both laboratory and clinic) with a diagnostic workload >20 cases per week in 23/154 (15%), 5-20 in 82/154 (53%) and <5 cases per week in 49/154 (32%). The consensus minimum diagnostic panel should include : CD19, CD5, CD20, CD23, Kappa and Lambda. Participants recommended the following markers: CD38, CD45, CD79b, CD10, CD22, CD43, CD200, and FMC7. A minimum and recommended panel with reproducible criteria for component reagents were determined and the criteria were applied to 10,876 cases diagnosed with a B-LPD, of which 8120 were CD5+ B-LPD. Out of 5947 sent as a primary referrals for diagnosis, 4493 (75.6%) met the proposed diagnostic criteria for CLL, 821 (13.8%) did not and had a clear alternative diagnosis (e.g. MCL) and 633 (10.6%) would not be readily classified by flow cytometry if the proposed criteria were applied. Out of 2173 cases previously diagnosed as CLL at another centre, 2028 (93.3%) met the proposed diagnostic criteria, 19 (0.9%) had a clear alternative diagnosis while 126 (5.8%) did not meet the flow-cytometry criteria. CONCLUSIONS: We present flow-cytometry criteria for the diagnosis of CLL largely consistent with current practice. In addition, reproducible definitions of the required expression pattern and performance characteristics of reagents are provided. Prospective evaluation of the proposed criteria as well as a parallel project to facilitate definitive diagnosis of CD5+ B-LPD cases that do not meet the proposed criteria are underway. Figure 1. required and recommended markers for use in the diagnosis of CLL with reagent specification based on expression patterns in normal peripheral blood. Figure 1. required and recommended markers for use in the diagnosis of CLL with reagent specification based on expression patterns in normal peripheral blood. ‡ Weak expression = median fluorescence intensity at least 20% lower than median for normal peripheral blood B-cells, reference range determined within each laboratory, based on ICSH/ISLH/CLIA guidelines for reproducibility *consensus, not specifically validated Disclosures Rawstron: Abbvie: Honoraria; Pharmacyclics: Research Funding; Celgene: Honoraria; Roche: Honoraria; BD Biosciences: Patents & Royalties; Gilead: Honoraria, Research Funding. Cuneo:Roche: Speakers Bureau; Gilead: Speakers Bureau; Jannsen: Speakers Bureau; Celgene: Speakers Bureau; Novartis: Speakers Bureau. Kern:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Trneny:Celgene: Consultancy, Honoraria, Other: Travel, accommodations, expenses, Research Funding. Mulligan:Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Speakers Bureau; Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi Aventis: Research Funding. Hillmen:Celgene: Research Funding; Gilead: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; GSK: Consultancy, Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Roche: Consultancy, Honoraria, Research Funding. Hallek:Gilead: Honoraria, Other: Speakers Bureau and/or Advisory Boards, Research Funding; Boehringher Ingelheim: Honoraria, Other: Speakers Bureau and/or Advisory Boards; Janssen: Honoraria, Other: Speakers Bureau and/or Advisory Boards, Research Funding; Mundipharma: Honoraria, Other: Speakers Bureau and/or Advisory Boards, Research Funding; Celgene: Honoraria, Other: Speakers Bureau and/or Advisory Boards, Research Funding; Roche: Honoraria, Other: Speakers Bureau and/or Advisory Boards, Research Funding; AbbVie: Honoraria, Other: Speakers Bureau and/or Advisory Boards, Research Funding; Pharmacyclics: Honoraria, Other: Speakers Bureau and/or Advisory Boards, Research Funding. Ghia:AbbVie: Consultancy; Janssen: Consultancy; Roche: Consultancy, Research Funding; Adaptive: Consultancy; Gilead: Consultancy, Research Funding, Speakers Bureau; GSK: Research Funding; Acerta Pharma BV: Research Funding; Pharmacyclics: Consultancy.

The diagnostic criteria for CLL rely on morphology and immunophenotype. Current approaches have limitations affecting reproducibility and there is no consensus on the role of new markers. The aim of this project was to identify reproducible criteria and consensus on markers recommended for the diagnosis of CLL. ERIC/ESCCA members classified 14 of 35 potential markers as “required” or “recommended” for CLL diagnosis, consensus being defined as >75% and >50% agreement, respectively. An approach to validate “required” markers using normal peripheral blood was developed. Responses were received from 150 participants with a diagnostic workload >20 CLL cases per week in 23/150 (15%), 5–20 in 82/150 (55%), and <5 cases per week in 45/150 (30%). The consensus for “required” diagnostic markers included: CD19, CD5, CD20, CD23, Kappa, and Lambda. “Recommended” markers potentially useful for differential diagnosis were: CD43, CD79b, CD81, CD200, CD10, and ROR1. Reproducible criteria for component reagents were assessed retrospectively in 14,643 cases from 13 different centers and showed >97% concordance with current approaches. A pilot study to validate staining quality was completed in 11 centers. Markers considered as “required” for the diagnosis of CLL by the participants in this study (CD19, CD5, CD20, CD23, Kappa, and Lambda) are consistent with current diagnostic criteria and practice. Importantly, a reproducible approach to validate and apply these markers in individual laboratories has been identified. Finally, a consensus “recommended” panel of markers to refine diagnosis in borderline cases (CD43, CD79b, CD81, CD200, CD10, and ROR1) has been defined and will be prospectively evaluated. © 2017 International Clinical Cytometry Society

We evaluated immune responses to Mycobacterium tuberculosis in 10 health-care workers (HCWs) and 10 non-HCWs and correlated their immune status with the development of active tuberculosis (TB). Twenty individuals were randomly recruited, tested, and monitored longitudinally for TB presentation. Peripheral blood mononuclear cells (PBMCs) from donors were stimulated with M. tuberculosis and tested for cell proliferation and the production of interferon (IFN)- gamma, interleukin (IL)-5, and IL-4, by use of enzyme-linked immunosorbent or flow-cytometric assays. HCWs had higher levels of cell proliferation (24,258 cpm) and IFN- gamma (6373 pg/mL) to M. tuberculosis than did non-HCWs (cell proliferation, 11,462 cpm; IFN- gamma, 3228 pg/mL). Six of 10 HCWs showed increased median percentages of CD8+IL-4+ (4.7%) and gammadelta +IL-4+ (2.3%) T cells and progressed to active TB. HCWs who remained healthy showed increased median percentages of CD8+IFN- gamma+ (25.0%) and gammadelta +IFN- gamma+ (8.0%) and lower percentages of CD8+IL-4+ (0.05%) and gammadelta +IL-4+ (0.03%) T cells.