The plasma cell associated antigen detectable by antibody VS38 is the p63 rough endoplasmic reticulum protein.

AIMS: To characterise the 64 kDa intracellular antigen present on normal and neoplastic plasma cells detected by monoclonal antibody VS38 and by another antibody, MC186, of similar reactivity. METHODS: The VS38 monoclonal antibody was used to screen a bacterially expressed peripheral blood cDNA library, and the immunocytochemical staining of the two antibodies was compared with those raised specifically to the protein identified as the VS38 antigen. RESULTS: A partial cDNA encoding the VS38 antigen was cloned and shown to be identical to the human p63 gene. p63 is a non-glycated, reversibly palmitoylated type II transmembrane protein which is found in rough endoplasmic reticulum. Antibody MC186 also recognised this protein and both VS38 and MC186 together with two antibodies raised to p63 gave identical immunostaining patterns. CONCLUSIONS: The VS38 antigen was identified as the rough endoplasmic reticulum protein p63. While it is not exclusively expressed on plasma cells, the presence of p63 distinguishes plasma cells from other lymphoid cells because of their high secretory activity.     

Immunocytochemical analysis of MNDA in tissue sections and sorted normal bone marrow cells documents expression only in maturing normal and neoplastic myelomonocytic cells and a subset of normal and neoplastic B lymphocytes.

The human myeloid cell nuclear differentiation antigen (MNDA) is a nuclear antigen known to be expressed in mature myelomonocytic cell lines. An extensive immunocytochemical evaluation of fixed tissues confirmed MNDA expression in normal maturing granulocytes and monocytes and in acute nonlymphocytic leukemias and chronic myelogenous leukemia. MNDA was not detected in normal tissue histiocytes but was found in activated macrophages and foreign body giant cells associated with inflammation. Flow cytometric cell sorting of normal bone marrow established that MNDA is initially expressed in myeloid blast cells. Examination of lymphoid tissues showed a low level of expression in a population of normal mande B lymphocytes but not in germinal center cells or plasma cells. A subset of B cell neoplasms expressing MNDA included hairy cell leukemia, parafollicular (monocytoid) B cell lymphoma, mantle cell lymphoma, and small lymphocytic lymphoma. Cell sorting of normal bone marrow showed MNDA expression in CD20+/CD10-/CD5- B cells. MNDA was not detected in other normal bone marrow or all other nonhematopoietic cells. The hematopoietic cell-specific pattern of MNDA expression was elucidated through a comprehensive analysis of normal and neoplastic tissues, and the results provide further evidence of the coexpression of B- and myeloid cell markers in neoplastic B cells and identify a normal B cell population that might be related to the cell of origin of a subset of B cell neoplasms.     

A panel of antibodies for the immunostaining of Bouin's fixed bone marrow trephine biopsies.

AIMS: To assess a panel of antibodies on Bouin's fixed bone marrow trephine (BMT) biopsies. These biopsies are widely used in routine diagnosis of various haematological malignancies and may be the sole material available in many centres; however, information regarding the immunostaining of this material is lacking. METHODS: Biopsies were taken from 72 patients presenting with various haematological malignancies (leukaemia, 38; lymphoma, 14; multiple myeloma, 20). A panel of antibodies was assessed on Bouin's fixed BMT biopsies by the alkaline phosphatase-antialkaline phosphatase method. RESULTS: Three B (MB2, LN-2, Ki-B5) and two T cell lineage antibodies (UCHL-1, CD3-r) reliably identified lymphoid cells, while MPO-r, Leu-M1/CD15, and KP-1/CD68 recognised cells from the myeloid or histiocytic/macrophage series. Reed-Sternberg cells were stained by LN-2, Leu-M1, and CD30. Antibodies specific for plasma cells (VS38) and hairy cells (DBA.44) gave a variable pattern of staining. Among the proliferation markers, proliferative cell nuclear antigen but not Ki-67 related antibodies were effective. CONCLUSION: This study presents a panel of antibodies with reactivity not restricted to common fixatives that are also suitable for Bouin's fixed BMT biopsies.     

Assessment of cell proliferation in normal and pathological bone marrow biopsies: a study using double sequential immunophenotyping on paraffin sections

The proliferative activity of the haematopoietic and plasma cells in bone marrow was evaluated under normal and neoplastic conditions, by means of a sequential double immunostaining technique, using monoclonal antibody MIB-1 recognizing the cell proliferation-associated nuclear antigen Ki-67, and antibodies against glycophorin-C, myeloperoxidase, factor VIII-related antigen, and immunoglobulin light chains. Fifty-eight B5 fixed, paraffin-embedded bone marrow biopsies were analysed, including 11 normal controls, 10 cases of myelodysplasia, 14 cases of chronic myeloproliferative disorder, eight cases of acute non-lymphoid leukaemia, and 15 cases of myeloma. In normal marrows, the highest proliferative activity was noticed in the erythroid cells (75% to 95%; mean 90%), in comparison with myeloid precursors (15% to 80%; mean 38%), and megakaryocytes (10% to 20%; mean 14%); no Ki-67 positive plasma cells were found. In all investigated haematological disorders, the expression of MIB-1 by erythroid cells was similar to that observed in controls. Similarly, the percentage of MIB-1+ myeloid precursors in chronic myeloproliferative disorders and myelodysplasia largely overlapped the values observed in normals, and comparable values were also found in the blast cells from acute non-lymphoid leukaemia type M1 and M2. These findings suggest that the evaluation of either erythroid or myeloid proliferative activity is of little value in the differential diagnosis between these myeloproliferative disorders. By contrast, the obvious increase of Ki-67 expression of megakaryocytes in chronic myeloproliferative disorders, with labelling also of micro-megakaryocytes, might sustain the diagnosis in controversial cases. Since cases of mature myeloma showed less than 2% of Ki-67 positive cells, evaluation of proliferative activity is of no value in the differential diagnosis with reactive plasmacytosis. The sequential double immunophenotyping for Ki-67 antigen and for haematopoietic cell lineage-associated markers can be applied in a consistent manner to routine bone marrow biopsies to evaluate proliferating cells in normal and neoplastic conditions.     

Neural cell adhesion molecule expression in plasma cells in bone marrow biopsies and aspirates allows discrimination between multiple myeloma, monoclonal gammopathy of uncertain significance and polyclonal plasmacytosis

AIMS: Differential diagnosis between multiple myeloma (MM), monoclonal gammopathy of uncertain significance (MGUS), and polyclonal plasmacytosis may be difficult in cases with not much bone marrow infiltration. Normal plasma cells express the antigens CD138, CD38, CD19, CD10 and D-related human leucocyte antigen (HLA-DR). Myelomatous plasma cells lack B lymphoid-associated markers and may express cell surface antigens associated with other haematopoietic lineages such as NCAM/CD56 (neural cell adhesion molecule). Recently, a monoclonal antibody, anti-CD56, has become available that can be used in fixed tissues embedded in paraffin, and it has been reported that osteoblastic cells of trabecular bone strongly express NCAM/CD56. METHODS AND RESULTS: We analysed NCAM molecule expression in 35 samples from patients with plasma cell disorders: 14 cases of MM, 16 cases of MGUS, and five cases of polyclonal plasmacytosis using immunohistochemistry in parallel in bone marrow core biopsies processed routinely and in bone marrow smears from the same patients. Of the MM samples 78% were CD56+ in smears and 92% positive in biopsies. We did not find strong CD56 expression in MGUS samples. One of five samples of polyclonal plasmacytosis was CD56+. A case was considered to be positive for CD56 expression if >50% of the CD138+ plasma cells expressed NCAM with an intensity on a par with that of the osteoblasts. CONCLUSION: We conclude that CD56 antibody is a very useful marker in the study of plasma cell proliferation in bone marrow biopsies and in bone marrow aspirates and is a great help in discriminating between MM, MGUS, and polyclonal plasmacytosis, especially in those cases with low infiltration.     

QBEND10 for the diagnosis of myelodysplastic syndromes in routinely processed bone marrow biopsy specimens.

AIM--The assessment of the value of the antibody QBEND10, which is directed against the haemopoietic stem cell related antigen CD34, in the immunohistochemical diagnosis of myelodysplastic syndrome in routinely processed bone marrow biopsy specimens. METHODS--581 formalin fixed, paraffin embedded trephine biopsy specimens of the iliac crest were immunostained with QBEND10 (avidin-biotin complex/ABC method). The number of CD34+ haemopoietic stem cells/blast cells (referred to hereafter as CD34+ cells) was determined in each case. The Wilcoxon test was used for statistical analysis. RESULTS--The following diagnostic categories were defined: (1) normal or reactive bone marrow (n = 356), (2) lymphoproliferative disorders, usually non-Hodgkin's lymphoma of low grade malignancy or multiple myeloma (n = 118), (3) myelodysplastic syndrome (n = 22), (4) acute leukaemia (n = 44), and (5) myeloproliferative diseases (n = 41). The average number of CD34+ cells was very low (0.2/HPF) in normal and reactive bone marrow, in lymphoproliferative disorders and in the myelodysplastic syndrome subtypes RA and RARS. Myeloproliferative diseases showed an average of three CD34+ cells/HPF. However, the average number of CD34+ cells was significantly higher (p < 0.05) in the myelodysplastic syndrome subtypes RAEB and RAEB-T (8.7/HPF) and in acute leukaemia (including both myeloid and lymphoblastic leukaemia; 111.7/HPF). CONCLUSIONS--QBEND10 is of value for the identification of RAEB and RAEB-T in routinely processed bone marrow biopsy specimens because it enables the detection of even small increases in the number of CD34+ cells.     

CD138 (syndecan-1), a plasma cell marker immunohistochemical profile in hematopoietic and nonhematopoietic neoplasms

We evaluated the immunohistochemical profile and specificity of CD138 reactivity in 238 specimens from hematopoietic and nonhematopoietic neoplasms. In 91 bone marrow biopsies, CD138 reactivity was observed for nonneoplastic plasma cells, neoplastic plasma cells in multiple myeloma cases (43/43), and the plasmacytic component in lymphoplasmacytic lymphoma cases (4/4). Stromal reactivity was noted in 7 multiple myeloma cases. Of 9 bone marrow specimens involved by metastatic carcinoma, tumor cells were CD138+ in 5 cases; stromal reactivity was noted in 7 cases. Studies of 76 nodal and extranodal lymphomas (B-cell, 49; T-cell, 8; Hodgkin lymphoma, 19), 1 Langerhans cell histiocytosis, and 14 nonneoplastic lymph nodes revealed CD138 reactivity only for nonneoplastic plasma cells, the neoplastic cells of 2 large B-cell lymphomas (immunoblastic type, plasmacytoid features), and the clonal plasmacytic component of 3 of 3 extranodal and 1 nodal marginal zone lymphoma. Evaluation of 56 epithelial and nonepithelial tumors revealed CD138 positivity for neoplastic cells of carcinomas of various types (30/33), frequently with associated stromal reactivity, and for neoplasms of mesenchymal, melanocytic, and other tumor types (12/23). Within the hematopoietic system, CD138 is an excellent marker of plasmacytic differentiation. Based on its broad staining profile, CD138 reactivity for neoplastic cells is not a definitive marker for plasmacytic derivation, unless a hematolymphoid origin has been established.     

CD31 (JC70) expression in plasma cells: an immunohistochemical analysis of reactive and neoplastic plasma cells.

AIMS: To investigate the immunohistochemical expression of CD31 (JC70) in normal and neoplastic plasma cells. METHODS: Plasma cells in bone marrow biopsies and extramedullary locations were examined. All extramedullary biopsies were formalin fixed and paraffin embedded. The bone marrow biopsies were fixed in formal acetic acid and embedded in paraffin wax. Twenty multiple myelomas (12 bone marrow and eight extramedullary deposits), 10 extramedullary plasmacytomas, and 30 biopsies with reactive plasma cells (10 bone marrow, 20 extramedullary biopsies) were stained with anti-CD31 (JC70) using the streptavidin-biotin detection system with diaminobenzidine as a chromogen. Antigen retrieval in bone marrow biopsies was achieved by pressure cooking. In all other biopsies, antigen retrieval was achieved by microwave pretreatment. RESULTS: All 20 extramedullary cases with reactive plasma cells showed intense membrane staining. Focal staining was detected in reactive plasma cells in bone marrow biopsies. Five of 10 plasmacytomas showed membrane staining. None of the cases of multiple myeloma, either medullary or extramedullary, showed any immunoreactivity for CD31. CONCLUSIONS: CD31, a member of the immunoglobulin supergene family of cell adhesion molecules, is strongly expressed in extramedullary reactive plasma cells, focally in bone marrow reactive plasma cells, and occasionally in extramedullary plasmacytomas.     

CD19 and immunophenotype of bone marrow plasma cells in monoclonal gammopathy of undetermined significance.

AIMS--To determine whether a particular phenotype or antigen is preferentially related to monoclonal gammopathies of undetermined significance (MGUS). METHODS--Bone marrow specimens from 56 patients with MGUS were stained immunocytochemically (ABC peroxidase) for CD38, CD56, CD9, CD10, CD19, CD20, CD22, and MB2. Specimens from patients recently diagnosed with multiple myeloma and reactive bone marrow samples were studied in parallel. RESULTS--CD38 was expressed on all plasma cells from all MGUS samples tested, while 36% were positive for CD56, CD9 and MB2 were both expressed strongly; CD20 was moderately expressed, and staining for CD10 and CD22 was uncommon. For these five B cell antigens there was no clear difference between their expression in MGUS and in multiple myeloma. A great difference was found for CD19: in MGUS this antigen was expressed on 2-91% of plasma cells (mean 35%) and 77% patients had > 10% positive plasma cells; in multiple myeloma its expression was low and only 12% patients had > 10% positive plasma cells. When these results were converted to numbers of CD19 positive plasma cells per 100 nucleated bone marrow cells, reactive bone marrow and MGUS specimens had a similar number of positive plasma cells. There was no correlation between expression of any of the antigens tested. CONCLUSIONS--Many of the so-called pre-B, B or activation antigens are present on plasma cells from MGUS specimens, and expression of CD9, CD10, CD20, CD22, MB2, and CD38 in MGUS was very similar to that in multiple myeloma. CD56 was frequently expressed in MGUS. In this series CD19 was highly expressed in MGUS but not in multiple myeloma. Plasma cells bearing this antigen could represent the non-neoplastic process and determination of its expression could be useful for the diagnosis of MGUS.     

Peanut agglutinin (lectin from Arachis hypogaea) binding to hemopoietic cells: an immunophenotypic study using a biotin streptavidin technique.

The lectin peanut agglutinin (PNA) was used to study the surface carbohydrate expression of galactose beta 1, 3, N-acetylgalactosamine by normal and malignant hemopoietic cells. Immunostaining was performed using biotinylated PNA and a streptavidin-alkaline phosphatase staining technique on 78 patients. The study was undertaken to enlarge on previous reports of lectin binding to cells of hemopoietic origin and to establish the potential role of biotinylated PNA as a component of an immunotoxin for in vitro purging of bone marrow in patients with multiple myeloma. In normals only monocytes, macrophages, centroblasts and plasma cells showed reactivity. Of the hematological malignancies, all cases of multiple myeloma were positive and non-Hodgkin's lymphoma cases with a large cell component had positive centroblasts. Two of 5 cases of acute myelomonocytic leukemia, one case of chronic myelomonocytic leukemia and one case of pleomorphic T cell non-Hodgkin's lymphoma showed PNA positive neoplastic cells. The reactivity of biotinylated PNA with centroblasts and plasma cells suggests that it may be of potential value when linked to a streptavidin-ricin conjugate in the in vitro purging of bone marrow of patients with multiple myeloma prior to autologous bone marrow transplantation.     

Use of APAAP technique on paraffin wax embedded bone marrow trephines.

The immunoalkaline phosphatase (APAAP) technique was applied to the labelling of decalcified sections of formalin fixed, paraffin wax embedded bone marrow trephine biopsy specimens. A panel of monoclonal antibodies reactive with haemopoietic and epithelial antigens, which survive routine formalin fixation, was assessed on 72 cases of haematological malignancy (including acute and chronic leukaemias and lymphomas) showing bone marrow infiltration. The APAAP method showed clear distinct labelling of antigen positive cells without loss of antigens due to decalcification. Both normal or reactive single cells present in the sample and neoplastic cell populations could be identified morphologically and their antigenic phenotype and cellular origin, whether lymphoid or myeloid, established. The application of the APAAP method to routinely prepared paraffin wax embedded trephines has many advantages over the assessment of specially prepared cryostat sections of bone marrow.     

The Mi15 monoclonal antibody (anti-syndecan-1) is a reliable marker for quantifying plasma cells in paraffin-embedded bone marrow biopsy specimens

Plasmocyte selective monoclonal antibodies (MAb) recognizing syndecan-1 have recently been described. They belong to a new cluster, CD138. Using the MAb MI15, we investigated the expression of syndecan-1 in routinely paraffin-embedded tissues. Nontumoral lymph nodes (25 cases) and bone marrow biopsy specimens (63 cases) showed strong membrane staining of plasma cells only, allowing accurate analysis of the nuclear structure. The MI15 positivity correlated with kappa and lambda light chain expression in the cytoplasm. The percentages of plasma cells calculated in bone marrow biopsy specimens after MI15 staining were, respectively, 2.1% (range, 1% to 4%) in normal bone marrows, 8.5% (range, 5 to 17) in reactive plasmocytosis, and 4.66% in monoclonal gammapathy of undetermined significance (MGUS) patients (range, 1 to 13), in the same range but slightly higher than those obtained on smears or on hematoxylin and eosin (H&E)-stained sections. In multiple myeloma (40 cases), all plasma cell types were marked, and Mi15 MAb gave additional information in 8 of 40 (20%) patients. In lymph nodes, Mi15 MAb reacted with Reed-Sternberg cells of classical Hodgkin's disease in 23 of 31 cases (74%) with variable intensity. In contrast, nodular lymphocyte predominance Hodgkin's disease (10 cases), most B cell lymphomas (88 of 107 cases) and all T cell lymphomas (30 cases) were negative. In B cell lymphomas, plasmocytomas (8 cases), plasmocytic lymphomas (2 cases), and 5 of 13 cases of immunoblastic lymphoma with plasmocytoid differentiation were stained. In lymphoplasmocytoid lymphomas (4 lymph nodes and 20 bone marrow biopsy specimens), only mature plasma cells were positive. Moreover, a wide distribution of syndecan-1 was observed in normal and tumoral epithelial tissues. Finally, Mi15 MAb appears to be a reliable marker for identifying and quantifying normal and tumoral plasma cells in paraffin-embedded bone marrow and lymph node samples.     

Immunohistochemical examination of routinely processed bone marrow biopsies.

Immunohistochemistry was performed on paraffin sections of 169 bone marrow biopsies fixed in a buffered methanol-formalin solution and decalcified with EDTA. The biopsies included specimens with normal hematopoiesis, and specimens that were affected by various hematological disorders as well as some metastatic carcinomas. The results demonstrate that a wide spectrum of antigens was preserved in routinely processed bone marrow biopsies, even after long-term fixation up to 12 days. Markers for granulopoietic cells were lysozyme, elastase, DAKO-M 1, and MT 1. Megakaryopoiesis was stained with glycoprotein IIIa, von Willebrand factor, and Ulex europaeus agglutinin (UEA), and erythropoiesis with LN 1. Normal lymphocytes as well as lymphoma cells of all non-Hodgkin's lymphomas tested were positive for leukocyte common antigen (LCA), and at variable degree, for MB 1, 4 KB 5, LN 1, LN 2, UCHL 1, or MT 1. Reed-Sternberg and Hodgkin's cells in Hodgkin's lymphomas were reactive with Ber-H 2, LN 2 and Dako-M 1. In plasma cell disorders, staining for immunoglobulin light chains gave best results. Metastatic carcinomas showed predominantly staining with EMA, and KL 1. A selected panel of specific cell markers is proposed, which proved to be helpful in routine bone marrow diagnosis in most cases.     

A case of aggressive multiple myeloma with cleaved, multilobated, and monocytoid nuclei, and no serum monoclonal gammopathy

Multiple myeloma is a B-cell malignancy characterized by proliferation of neoplastic plasma cells. A few cases have been reported identifying variant forms of neoplastic plasma cells with atypical nuclei that secrete myeloma protein. We report a highly unusual case of plasma cell myeloma that presented with cleaved, multilobated, and monocytoid nuclei, without detectable myeloma protein in the serum or urine. The bone marrow contained sheets of plasma cells exhibiting pleomorphic nuclei with cleaved, multilobated, and monocytoid features that were negative for myeloperoxidase and dual esterase. Flow cytometric analysis revealed CD38high/CD45low cells expressing cytoplasmic kappa light chain, without evidence of myeloid or lymphoid differentiation. Following chemotherapy, the patient developed secondary plasma cell leukemia. A high plasma cell labeling index was obtained from bone marrow and peripheral blood, indicating a poor prognosis. In addition to quantitative immunoglobulins, serum protein electrophoresis, and immunofixation electrophoresis of serum and urine, we recommend cytochemical and flow cytometric studies for evaluation of suspected plasma cell myeloma with atypical cellular features.     

VS38 immunostaining in melanocytic lesions.

AIMS: To investigate the immunoreactivity of a range of melanocytic lesions, both benign and malignant, with the monoclonal antibody VS38. This was recently described as a marker of reactive/neoplastic plasma cells and, therefore, is useful in the diagnosis of plasmacytoma/myeloma and lymphomas with plasmacytic differentiation. This study was prompted by the recent observation that a plasmacytoid melanoma arising in the nasal cavity was strongly immunoreactive with VS38, which was therefore a potential source of major diagnostic error. METHODS: The Streptavidin-peroxidase complex technique was used on paraffin wax embedded sections of 167 melanocytic lesions. Diaminobenzidine (DAB) was used as chromogen for non-pigmented or lightly pigmented lesions and nickel/DAB for more heavily pigmented lesions. RESULTS: Positive immunostaining for VS38 was seen in 14.5% (10/69) of benign naevi (including 40% (four of 10) of Spitz naevi), 10.5% (two of 19) of dysplastic naevi/in situ melanomas, 92% (35/38) of primary cutaneous melanomas, 100% (four of four) of primary mucosal melanomas, 91.7% (33/36) of recurrent/metastatic melanomas, and 100% (one of one) of clear cell sarcomas of soft tissues. CONCLUSIONS: VS38 immunostaining is frequently positive in primary and recurrent/metastatic malignant melanoma and is also reactive less commonly with benign naevi. These results should be borne in mind when this recently described marker of normal/neoplastic plasma cells is used to identify tumour lineage, particularly in tumours arising at unusual sites, such as in the nasal cavity. The possibility of malignant melanoma should be actively considered and excluded in any undifferentiated tumour which shows VS38 immunoreactivity.     

Plasmablastic lymphomas may occur as post-transplant lymphoproliferative disorders

AIMS: To describe four cases of plasmablastic lymphoma arising in the unusual setting of a post-transplantation lymphoproliferative disorder (PTLD). METHODS AND RESULTS: Four cases were encountered over 2 years in human immunodeficiency virus (HIV)-negative patients following renal, heart or bone marrow transplantation. The cases were routinely processed and immunohistochemistry was performed. The cases showed blastic non-Hodgkin's lymphoma morphology and plasma cell-like immunophenotypic features: minimal or absent expression of leucocyte common antigen and CD20, variable CD79a and VS38 positivity. Monoclonal light chain restriction was also detected. CONCLUSIONS: The emphasis of this paper is to document further the occurrence of plasmablastic lymphomas in HIV- individuals and to expand the spectrum of PTLD.     

Detection of T cells in paraffin wax embedded tissue using antibodies against a peptide sequence from the CD3 antigen.

Rabbit polyclonal antibodies were raised against a proline rich, peptide sequence, comprising 13 amino acids, in the cytoplasmic domain of the CD3 epsilon chain. Immunoprecipitation experiments showed that this antibody preparation recognised the CD3 antigen on human T lymphoblasts. The antibody stained normal T cells strongly in tissue sections which had been fixed in formalin or Bouin's solution and embedded in paraffin wax. Its reactivity with T cell lymphoma, when evaluated on a series of 96 previously phenotyped cases, closely agreed with the results obtained on cryostat sections. These results indicate that the specific detection of T cells in routinely processed tissue biopsy specimens is now technically feasible on a wide scale in diagnostic laboratories using CD3 peptide antibodies, and they also suggest that in future the use of anti-peptide antibodies may detect other lineage specific antigenic markers in paraffin wax sections.     

Expression of VEGF in routinely fixed material using a new monoclonal antibody VG1

The aim of this study was to raise and characterize a monoclonal antibody reactive with VEGF (vascular endothelial growth factor) in routinely fixed specimens and to use it to investigate its tissue distribution in normal and pathological specimens. Recombinant VEGF 189 protein was used to raise a monoclonal antibody. The specificity of the antibody was confirmed using COS cells transfected with cDNA coding for VEGF 121, 165 and 189 protein and by western blotting studies. The resulting antibody VG1 was shown to react with the 121, 165 and 189 isoforms of VEGF protein in routinely processed material. In normal tissues, there was strong staining of endometrial and salivary glands and of the mucosa of the gastro-intestinal tract. In tumours, a proportion of the neoplastic cells in lung and breast cancer and in melanoma were labelled. In all tissues, whether normal or malignant, striking VEGF positivity was seen in plasma in vessels and stroma. This study has shown that antibody VG1 detects the 121, 165 and 189 VEGF isoforms in routinely fixed specimens. The results of the normal tissue and tumour labelling are in agreement with other studies using alternative methods of detection. This should be a useful and reliable reagent for studies of VEGF and angiogenesis in human pathological material.     

Comparison of touch imprints with aspirate smears for evaluating bone marrow specimens.

We compared the differential counts of normal and abnormal bone marrow from touch imprints with those from aspirate smears to determine whether the touch imprint was reliable for independent routine use in the examination of bone marrow and the classification of hematologic abnormalities. Normocellular bone marrow specimens were obtained from 87 patients without hematologic abnormality. Abnormal bone marrow specimens were obtained from 173 patients with treated or untreated neoplastic hematologic disease, including acute myeloid leukemia, myelodysplastic syndrome, chronic lymphocytic leukemia, non-Hodgkin lymphoma, hairy cell leukemia, myeloma, and acute lymphoblastic leukemia. We found no diagnostic difference in the differential counts from touch imprints and aspirate smears of normocellular bone marrow, and although we found some difference between the differential counts in certain cases of diseased bone marrow, the touch imprint proved to be a reliable diagnostic tool for determining the cellular composition of normal bone marrow and more reliable for the diagnosis of bone marrow involved by a neoplastic hematologic disease. Our findings suggest that evaluating touch imprints should be considered a standard practice in examining bone marrow.     

Utilization of monoclonal antibody L26 in the identification and confirmation of B-cell lymphomas. A sensitive and specific marker applicable to formalin-and B5-fixed, paraffin-embedded tissues.

Immunophenotypic analysis of paraffin-embedded tissues of lymphoproliferative disorders has been facilitated by recent developments of monoclonal antibodies that react with epitopes that survive histologic processing. Leukocyte common antigen (LCA) antibody has made a significant contribution to the immunocytochemical separation of non-Hodgkin's lymphomas from nonlymphoid neoplasms. However, a small percentage of lymphomas, particularly some large cell or immunoblastic B-cell tumors, will not label with LCA antibody. Other antibodies, directed against B lymphocytes, experience problems of specificity and a lack of sensitivity when applied to formalin-fixed specimens. The authors recently investigated a monoclonal antibody (L26) that demonstrates excellent specificity and sensitivity for B lymphocytes, and tumors derived from them, in formalin- and B5-fixed, paraffin-embedded tissue. The avidin-biotin peroxidase complex (ABC) technique was utilized for immunostaining 95 cases of malignant lymphoproliferative disorders and a variety of normal and neoplastic nonlymphoid tissues. When applied to sections of benign lymphoid tissue, the L26 antibody labeled germinal center cells, mantle zone and scattered interfollicular lymphocytes, but not histiocytes or plasma cells. L26 marked 100% (44/44) of the large cell and immunoblastic B-cell lymphomas, along with 1 case of pre-B cell lymphoblastic lymphoma. This included 8 cases that were LCA-negative. None of the T-cell lymphomas or plasma cell tumors studied demonstrated L26 immunostaining. No normal, benign, or neoplastic nonlymphoid tissues examined stained with this antibody. L26 successfully labels B lymphocytes and B-cell lymphomas in routinely processed tissues, often with greater sensitivity and intensity than LCA. This antibody should prove invaluable in the investigation of atypical lymphoid proliferations and the identification of B-cell derived lymphomas, when fresh or frozen tissue is unavailable for analysis.