Validation of cell-based fluorescence assays: practice guidelines from the ICSH and ICCS - part IV - postanalytic considerations.

Flow cytometry and other technologies of cell-based fluorescence assays are as a matter of good laboratory practice required to validate all assays, which when in clinical practice may pass through regulatory review processes using criteria often defined with a soluble analyte in plasma or serum samples in mind. Recently the U.S. Food and Drug Administration (FDA) has entered into a public dialogue in the U.S. regarding their regulatory interest in laboratory developed tests (LDTs) or so-called home brew assays performed in clinical laboratories. The absence of well-defined guidelines for validation of cell-based assays using fluorescence detection has thus become a subject of concern for the International Council for Standardization of Haematology (ICSH) and International Clinical Cytometry Society (ICCS). Accordingly, a group of over 40 international experts in the areas of test development, test validation, and clinical practice of a variety of assay types using flow cytometry and/or morphologic image analysis were invited to develop a set of practical guidelines useful to in vitro diagnostic (IVD) innovators, clinical laboratories, regulatory scientists, and laboratory inspectors. The focus of the group was restricted to fluorescence reporter reagents, although some common principles are shared by immunohistochemistry or immunocytochemistry techniques and noted where appropriate. The work product of this two year effort is the content of this special issue of this journal, which is published as 5 separate articles, this being Validation of Cell-based Fluorescence Assays: Practice Guidelines from the ICSH and ICCS - Part IV - Postanalytic considerations.

Tissue-microarray based immunohistochemical analysis of survival pathways in nodular sclerosing classical Hodgkin lymphoma as compared with Non-Hodgkin's lymphoma.

Neoplastic cells rely on key oncogenic pathways for their gain of proliferative and/or loss of apoptotic potential. Therapy targeted at specific points in these pathways has the potential to eliminate cancer cells by inducing differentiation or apoptosis. Concurrent immunophenotypic evaluation of survival pathways in nodular sclerosing classical Hodgkin lymphoma (cHL-NS) tissues has not previously been undertaken. We took the tissue microarray (TMA)-based approach to retrospectively evaluate the activation state of key oncogenic pathways by immunohisto-chemistry (IHC) in a series of 6 cases of cHL-NS (with predominantly syncitial areas). For comparison, 2 cases of diffuse large B-cell lymphoma (DLBCL), and 1 case of follicular hyperplasia (FH) were included in the study. Infiltration of T regulatory cells (Tregs) in the tumor microenvironment was assessed by expression of the Foxp3 transcription factor. Differential upregulation of the mitogen-activated protein kinase (MAPK)-extracellular signal related kinase (ERK), signal transducers and activators of transcription (STAT)3, and protein kinase c - alpha (PKC-alpha) pathways was seen among the cHL cases, whereas nuclear factor - kappa B (NF-kB) and phosphoinositide 3 kinase (PI3 K)-AKT-mammalian target of rapamycin (mTOR) pathways were equally activated in the neoplastic Reed-Sternberg cells of the 6 cHL-NS cases. Marked difference in the morphoproteomic profile was seen amongst the two cases of DLBCL. The amount of Foxp3+ T regulatory cells (Tregs) in the tumor microenvironment was highly variable ranging from 6/hpf to 120/hpf in cHL-NS, and 1/hpf to 82/hpf in DLBCL. In this pilot study, concurrent evaluation of oncogenic pathways in cHL-NS and DLBCL offers powerful insights in the putative therapeutic targets for an individualized approach to diagnosis and therapy.

Anaplastic large cell lymphoma in leukemic phase: extraordinarily high white blood cell count.

Anaplastic large cell lymphoma (ALCL) is a distinct type of T/null-cell non-Hodgkin lymphoma that commonly involves nodal and extranodal sites. The World Health Organization of lymphoid neoplasms recognizes two types: anaplastic lymphoma kinase (ALK) positive or ALK negative, the former as a result of abnormalities involving the ALK gene at chromosome 2p23. Patients with ALCL rarely develop a leukemic phase of disease, either at the time of initial presentation or during the clinical course. Described herein is a patient with ALK+ ALCL, small cell variant, associated with the t(2;5)(p23;q35), who initially presented with leukemic involvement and an extraordinarily high leukocyte count of 529 x 10(9)/L, which subsequently peaked at 587 x 10(9)/L. Despite chemotherapy the patient died 2(1/2) months after diagnosis. In the literature review 20 well-documented cases are identified of ALCL in leukemic phase reported previously, with a WBC ranging from 15 to 151 x 10(9)/L. Leukemic phase of ALCL occurs almost exclusively in patients with ALK+ ALCL, most often associated with the small cell variant and the t(2;5)(p23;q35), similar to the present case. Patients with leukemic phase ALK+ ALCL appear to have a poorer prognosis than most patients with ALK+ ALCL.

A teaching database for diagnosis of hematologic neoplasms using immunophenotyping by flow cytometry.

CONTEXT: In the diagnosis of lymphomas and leukemias, flow cytometry has been considered an essential addition to morphology and immunohistochemistry. The interpretation of immunophenotyping results by flow cytometry involves pattern recognition of different hematologic neoplasms that may have similar immunologic marker profiles. An important factor that creates difficulty in the interpretation process is the lack of consistency in marker expression for a particular neoplasm. For this reason, a definitive diagnostic pattern is usually not available for each specific neoplasm. Consequently, there is a need for decision support tools to assist pathology trainees in learning flow cytometric diagnosis of leukemia and lymphoma. OBJECTIVE: Development of a Web-enabled relational database integrated with decision-making tools for teaching flow cytometric diagnosis of hematologic neoplasms. DESIGN: This database has a knowledge base containing patterns of 44 markers for 37 hematologic neoplasms. We have obtained immunophenotyping data published in the scientific literature and incorporated them into a mathematical algorithm that is integrated to the database for differential diagnostic purposes. The algorithm takes into account the incidence of positive and negative expression of each marker for each disorder. RESULTS: Validation of this algorithm was performed using 92 clinical cases accumulated from 2 different medical centers. The database also incorporates the latest World Health Organization classification for hematologic neoplasms. CONCLUSIONS: The algorithm developed in this database shows significant improvement in diagnostic accuracy over our previous database prototype. This Web-based database is proposed to be a useful public resource for teaching pathology trainees flow cytometric diagnosis.

Immunophenotypic profile predictive of KIT activating mutations in AML1-ETO leukemia.

Translocation (8; 21)/AML1-ETO is considered a favorable cytogenetic abnormality in acute myeloid leukemia (AML). However, associated KIT activating mutations confer poor outcome. The immunophenotype associated with KIT mutations in AML1-ETO has not previously been elucidated. We retrospectively reviewed the immunophenotype by flow cytometry of 56 cases of AML with t(8; 21) and compared them with 100 cases of AML without t(8; 21). In 21 t(8; 21) cases, we sought KIT mutations by direct sequencing. Although CD19 and CD56 were aberrantly expressed in 42 (75%) of 56 and 46 (82%) of 56 cases, respectively, with t(8; 21), these markers were only expressed in 4% and 25%, respectively, without t(8; 21) (P < .001). However, the 5 KIT-mutated cases (D816H, 3; D816Y, 1; and N822K, 1) of t(8; 21) AML had diminished CD19 expression (P = .04) with definite CD56 expression (P = .30) on myeloid blasts. Our study suggests that KIT activating mutations in AML with t(8; 21) are associated with diminished CD 19 and positive CD56 expression on leukemic blasts and, thus, can be phenotypically distinguished from AML1-ETO leukemias without KIT mutations.

Utility of SKP2 and MIB-1 in grading follicular lymphoma using quantitative imaging analysis.

Follicular lymphoma is classified into grades (G)1, 2, and 3 based on the number of centroblasts in neoplastic follicles. However, the accuracy of manually counting these centroblasts is limited by certain cells (large centrocytes, follicular dendritic cells, and histiocytes) that could mimic centroblast morphology. The reproducibility of follicular lymphoma grading is dependent upon observer experience; therefore, significant variations occur. This study is to explore a more objective, reliable way of grading follicular lymphoma using a quantitative imaging system in conjunction with immunostains with antibodies to proliferation markers MIB-1 and S-phase kinase-associated protein 2 (SKP2). Fifty-eight follicular lymphomas (G1, n = 23; G2, n = 18; and G3, n = 17) were studied on formalin-fixed, paraffin-embedded sections. Positive nuclear staining of both Ki-67 and SKP2 was recorded using the quantitative Clarient ACIS II system (Aliso Viejo, CA, USA). Ten high-power fields (x400) from randomly selected neoplastic follicles were counted by a pathologist blinded to the previously assigned morphologic grade. The results show that the percentages of Ki-67+ and SKP2+ cells significantly differ among the different grades of follicular lymphoma. A higher grade of follicular lymphoma is associated with a higher percentage of Ki-67+ and SKP2+ cells. The overall SKP2+% cells are substantially lower than Ki-67+% cells in the same grade of follicular lymphoma. Statistical significance is observed in Ki-67+ cells between follicular lymphoma G1 and follicular lymphoma G3 and between G1 and G2. In contrast, statistical significance is noted in SKP2+% cells between follicular lymphoma G1 and follicular lymphoma G3 and between follicular lymphoma G2 and follicular lymphoma G3. The findings suggest that the SKP2 expression has better discrimination with grades of follicular lymphoma than Ki-67 expression. Compared with traditional methods, quantitation of SKP2 expression using a quantitative image analysis system might be a useful and objective approach in grading follicular lymphoma.

Cytologic diagnosis of ciliated hepatic foregut cyst.

Ciliated hepatic foregut cyst (CHFC) is a rare, benign, solitary cyst occurring most often in the left lobe of the liver. CHFCs are typically found incidentally during radiologic imaging, surgical exploration, or autopsy. Only six cases of CHFC diagnosed by fine needle aspiration have been reported in the literature. We describe a CHFC diagnosed by aspiration in a 70-yr-old woman who presented with a 2-yr history of abdominal discomfort. The radiologically benign-appearing lesion was located in the subcapsular area of segment IV of the liver. The aspirate contained benign ciliated columnar cells and goblet cells suspended in mucoid material. Sections from a cell block demonstrated pseudo-stratified bronchial-type epithelium with mucin secreting cells and an absence of cartilage, characteristic of CHFC. Mucin-containing goblet cells stained with alcian blue. The neuroendocrine cells within the bronchial-type epithelium stained for calcitonin and synaptophysin. On follow-up, a computed tomography (CT) demonstrated the cyst to be unchanged, but as the patient continued to have pain, sclerosis of the cyst was planned. The diagnosis of CHFC by fine needle aspiration and its distinction from other solitary cysts of the liver may prevent unnecessary surgical exploration and excision.

Isolation of a mycoplasma-specific binding peptide from an unbiased phage-displayed peptide library.

An important goal in medicine is the development of methods for cell-specific targeting of therapeutic molecules to pathogens or pathogen-infected cells. However, little progress has been made in cell-specific targeting of bacterially infected cells. Using a phage display approach, we have isolated a 20-mer peptide that binds to Mycoplasma arginini infected pancreatic beta-cells in tissue culture. This peptide binds to M. arginini infected beta-cells 200 times better than a control phage and is specific for the infected cells. Furthermore, transferring the M. arginini contamination to another cell line renders the newly infected cell line susceptible to peptide binding. Immunolocalization experiments suggest that the peptide is binding to M. arginini adhered to the cell surface. The free synthetic peptide retains its binding in the absence of the phage vehicle and tetramerization of the peptide increases its affinity for the infected cells. Efforts have been made to use this peptide to eliminate Mycoplasma from infected cell lines using ferromagnetic beads coated with the selected peptide. A ten-fold reduction of infection was accomplished with one fractionation via this approach. Our results suggest that this peptide, isolated from an unbiased selection, may be of utility for the detection and reduction of Mycoplasma infection in cultured cells. Furthermore, a general implication of our findings is that phage display methods may be useful for identifying peptides that target a broad array of other biological pathogens in a specific fashion.