Chronic B-cell leukemias: relation between morphological and immunological features

B-cell chronic lymphocytic leukaemia stage 0. An immunophenotypic study of 66 cases and comparison with B small cell lymphomas

The cells of 66 B-CLL stage 0 patients were analyzed using a large panel of monoclonal antibodies in order to better define the immunophenotype of B-CLL. The data were compared with the immunophenotypes of lymph node cells from 51 patients with diffuse B small cell lymphoma or leukaemia with lymph node enlargement. The most frequent immunophenotype of B-CLL stage 0 was SIgM(D)+ EmR+ CD5+ CD9+ CD21+ CD23+ CD35- CD38-. Among the lymphomas, EmR-positive and EmR-negative cases were identified. The vast majority of the EmR-positive cases usually showed the leukaemic pattern, immunophenotype and lymph node histology of B-CLL. The EmR-negative cases usually had immunophenotypes quite different from those of B-CLL and the histology of indented cell lymphoma (centrocytic or intermediate) or features of lymphoplasmacytoid/cytic lymphoma. More than 20% of EmR-positive cells proved to be the most important marker to distinguish B-CLL from other lymphocytic lymphomas. Indeed this was a sign of better prognosis. Lymphoplasmacytoid/cytic lymphomas were EmR-positive with the immunophenotype of B-CLL or EmR-negative with a definitely different immunological profile. This suggests two morphologically similar but biologically different subgroups of these diseases.

Human CD5-positive B cells in lymphoid malignancy and connective tissue diseases

The current literature on human CD5-positive B cells (CD5 + B cells) has been analysed, with a special emphasis on non organ-specific auto-immune diseases. Malignant cells of most of the chronic lymphoid leukaemias of the B cell lineage express the CD5 molecule. Antibodies of the IgM class produced by leukaemic B cells are multispecific auto-antibodies. The CD5 + B cell subset may be expanded in non organ-specific autoimmune diseases, such as rheumatoid arthritis, primary Sjögren's syndrome, systemic lupus erythematosus. This holds true for various conditions, including organ-specific auto-immune diseases. Since auto-immune features are common in lymphoproliferative disorders, and the latter be a complication in non organ-specific auto-immune diseases, CD5 + B cells may represent an intermediary between these auto-immune diseases and B cell lymphoproliferations. Studies on the regulation of CD5 + B cell production and function are likely to shed light on the aetiology of, and pathogenetic mechanisms operating in the different disease states.

Expression of CD45 isoforms in chronic B-cell leukaemias

CD45 isoform expression was studied in 204 cases of B-cell lymphoproliferative disease, including 162 chronic lymphocytic leukaemia (CLL). In almost half the samples tested, CD45R0 was co-expressed with CD45RA, unlike normal B-cells, which express only CD45RA, except at terminal stages of differentiation. In a small number of cases CD45R0 was the dominant isoform expressed. No correlation could be discerned either with Binet or RAI staging in CLL or with disease type CLL, prolymphocytic leukaemia (PLL) or hairy cell leukaemia (HCL). Comparison of CD45 isoform expression with other markers showed no correlation with apparent maturational status of the cells involved.

Immunoglobulin V gene expression in CD5 B-cell malignancies

Chronic lymphocytic leukemia (CLL) and small lymphocytic lymphomas (SLL) generally are malignancies of CD5 B cells. Immunophenotypic and clinicopathologic data, however, are required to distinguish subtypes that apparently have a different cytogenesis than that of conventional CLL or SLL. In addition to expressing CD5, neoplastic cells of the latter are also distinctive in that they frequently coexpress surface immunoglobulin (Ig), bearing one or more cross-reactive idiotypes (CRIs) (e.g. 17.109, G6,) that commonly are found on monoclonal IgM autoantibodies. The frequent occurrence of such CRIs reflects both the biased rearrangement and subsequent selected expression of Ig V genes with little or no somatic mutation. IgM/L CLL, for example, frequently (8/33) harbor abortive Ig rearrangements involving Humkv325, the VK gene encoding the 17.109-CRI. Also, the VH1 gene(s) encoding the G6 CRI accounts for over 10% of all VH genes and over 60% of all the VH1 genes used in randomly selected common CLL/SLL. Furthermore, comparison with the Ig expressed by nonmalignant G6 CRI+ B cells reveals an apparent restriction in the CDR3 of IgH expressed by G6 CRI+ CLL. Coupled with the observed potential bias in antibody light chain and heavy chain pairing in B-CLL, these data suggest that the autoantibodies expressed in this disease are selected based on antigen-binding activity. Collectively, our studies indicate that nonstochastic Ig V gene rearrangement and subsequent selection may influence the Ig repertoire expressed in this common B-cell malignancy.

Surface immunoglobulin density in the differential diagnosis of B-cell chronic lymphocytic leukemia and leukemic immunocytoma

Using flow cytometry peripheral blood samples of 37 consecutive patients with B-cell chronic lymphocytic leukemia (B-CLL) and 17 consecutive patients with leukemic immunocytoma (IC) were studied in order to determine quantitative differences in the surface immunoglobulin (slg) density. In 8/37 (21.6%) cases of B-CLL and 1/17 (5.9%) cases of IC slg staining remained in the control level. Analysis of slg-positive cases demonstrated a close association between the amount of slg and diagnosis: per case the mean calculated fluorescence intensity for IC lymphocytes was 209.7 arbitrary linear intensity units (IU) (median: 156.4, standard error of the mean (SEM): 53.7) and for B-CLL lymphocytes 10.8 IU (median: 7.3, SEM: 1.1; p less than 0.0001). Altogether, 94.6% of all B-CLL patients and 76.5% of all IC patients were correctly classified when a cut-off point was fixed at a mean fluorescence intensity value of 20.0 IU. The percentage of leukemic cells as characterized by CD19 and HLA-DR reactivity was significantly lower in cases of IC (p less than 0.03 and p less than 0.01, respectively). In both entities disease progression occurred more frequently in advanced stages (II-IV) according to the Rai classification (p less than 0.01). In progressive disease rather than in stable disease circulating T lymphocytes were shown to express decreased amounts of surface CD3 antigen (p less than 0.02). We conclude that the quantitative assessment of surface antigens in addition to their qualitative characterization provides accurate information. In particular, the diagnostic discrimination between B-CLL and IC may be improved by determining the lymphocytes' slg amount.

Bone marrow diagnosis in lymphoproliferative disorders: comparison of results obtained from conventional histomorphology and immunohistology

In this study we have investigated 313 bone marrow biopsies from 280 patients with lymphoproliferative disorders. Trephines were sectioned transversely to obtain one cylinder for cryostat sectioning and immunostaining and a second for histomorphological evaluation using a plastic-embedding technique. The results obtained by histomorphological and immunohistological evaluation were compared for their contribution to staging and classification. Using both techniques, bone marrow involvement was seen in 3/43 (7.0%) biopsies from patients with Hodgkin's disease and in 193/270 (71.5%) cases with non-Hodgkin's lymphoma, including multiple myeloma and acute lymphocytic leukaemia. Immunohistology proved superior in detecting minimal mainly interstitial bone marrow infiltration in 15 leukaemia/lymphoma cases. Biopsies showing infiltration with both methods (n = 157) were re-examined for classification of lymphomatous infiltrates. Whereas immunohistology did not provide additional information in cases with Hodgkin's disease and myeloma, this method was crucial for establishing the definitive diagnosis in a number of cases with acute lymphocytic leukaemia and non-Hodgkin's lymphoma. In all of six leukaemia cases, in which no or inadequate material was available for immunophenotyping of cell suspensions, immunohistology clearly defined the subtype. In the 140 cases of non-Hodgkin's lymphoma the majority of cases (76.4%) were identically classified. In some cases, with important prognostic and therapeutic implications, immunohistology alone provided the definitive diagnosis: T-cell lymphoma (n = 2), hairy cell leukaemia (n = 2) and centrocytic non-Hodgkin's lymphoma (n = 3). Bone marrow immunohistology is, therefore, an important supplement for classical lymphoma/leukaemia diagnosis. The differences observed between histomorphology and immunohistology emphasize the importance of lymph node biopsy in lymphoma classification.

Human B cells express membrane-bound and soluble forms of the CD14 myeloid antigen

The expression of the myeloid differentiation antigen CD14 on the B lineage was analyzed. A CD14-specific monoclonal antibody was used to isolate the antigen from normal B, B-type chronic lymphocytic leukemia cells, and a representative Epstein-Barr virus-transformed B lymphoblastoid cell line (EBVLCL). A soluble form of this protein was detected in the culture supernatant of all the B cell types tested. The molecule expressed in the normal B and B-type chronic lymphocytic leukemia cells was identical in size to the 52,000 mol. wt monocyte-isolated CD14 glycoprotein. A 64,000 mol. wt antigen was isolated from the lymphoblastoid cell line. Similar 2-D gel electrophoretic patterns to that of the monocyte-derived CD14 were obtained from the normal B and B-type chronic lymphocytic leukemia cell-isolated molecules. These similarities were reflected in minor isoelectric point (pI) differences between the polypeptide spots (pI 4.8), in the first dimension, and identical molecular weight (52,000) in the second dimension. The EBVLCL-isolated polypeptide, when analyzed by 2-D gel electrophoresis, showed a pI identical to that of the myeloid antigen (pI 4.6). The isolated soluble form was of smaller (47,000 mol. wt, normal B and B-type chronic lymphocytic leukemia cells) or similar size (64,000 mol. wt, lymphoblastoid cell line) compared with their corresponding membrane-bound forms. Interestingly, two-colour immunofluorescence analysis showed that only two out of four CD14-specific mAb tested bound to the B cells. We conclude that the CD14 antigen is, in fact, expressed in the B lineage. Its cell surface expression and serum level in the prognosis of B-type chronic lymphocytic leukemia patients needs to be evaluated.

Morphological and immunological changes of hairy cell leukemia during alpha-2-interferon therapy

We describe a patient who presented with the clinical picture of hairy cell leukemia (HCL). Bone marrow and peripheral blood lymphoma cells showed morphological and immunological features of HCL. Under recombinant alpha-2-interferon (alpha-2-IF) therapy the characteristic morphology changed from HCL to prolymphocytic leukemia (PLL). At diagnosis the lymphoma cells expressed CD24 and FMC7 surface antigen, but stained negative for surface immunoglobulins, light chains and anti-CD5. During alpha-2-IF treatment surface antigen expression changed to CD24, CD5 and FMC7. Surface IgD and lambda light chains became strongly positive. Southern Blot analysis of peripheral blood mononuclear cells showed two rearranged immunoglobulin bands at diagnosis but only one upon alpha-2-IF therapy. These data suggest, that this patient suffered from a biclonal lymphoma, HCL and PLL. While undergoing alpha-2-IF treatment the HCL came into remission, whereas the PLL clone proved to be poorly sensitive to alpha-2-IF therapy.

Chronic lymphocytic leukemia (CLL) in younger adults: a retrospective study of 133 cases

Clinical and biological data have been evaluated, using both univariate and Cox's multivariate statistical analyses, in a series of 133 Chronic Lymphocytic Leukemia (CLL) patients with a mean age of 46.6 years (range 31-50). In univariate analyses, anemia (Hb less than 13 g/dl), peripheral blood (PB) lymphocytosis (greater than 40 x 10(9)/l) and bone marrow (BM) lymphocytosis (greater than 80 per cent) were shown to be of significant prognostic value. Multivariate analysis, through a forward stepwise procedure, showed that the most important and independent variable is the BM lymphocytosis. These results are different from those obtained in previous studies and particularly in a recent identical study performed by the same Cooperative Group on 1777 patients with a mean age of 64.2 years (Mandelli et al., 1987). No significance can be demonstrated in stratifying this series of younger patients according to different staging methods (Rai et al., 1975; Binet et al., 1981b; Mandelli et al., 1987). Therefore this population of CLL patients, with less than 50 years of age, has risk factors quite different from classical CLL. The results of the present study show that the diagnostic approach to B-CLL in younger adults must be more complete: using the common diagnostic criteria, established staging systems appear to be inadequate in this series of younger patients.

Flow cytometric characterization of chronic lymphocyte leukaemias using orthogonal light scattering and quantitative immunofluorescence

Light scattering properties and antigen distribution of lymphocytes labeled with the monoclonal antibodies CD 5 and CD 20 were determined for 19 patients with a chronic B-cell derived leukaemia. The density of the antigen detected by the monoclonal antibody CD 5 appeared to be considerably lower on malignant B-lymphocytes of the patients as compared with T lymphocytes. A large variation was observed in the amount of receptors for the monoclonal antibodies CD 5 and CD 20 on the malignant cells of the different patients. B-cell chronic lymphocytic leukaemia (B-CLL) patients were clearly distinguishable from leukaemic follicular non Hodgkin lymphoma patients (LF-NHL, formerly lymphosarcoma cell leukaemia) and from a patient with a prolymphocytoid transformation (PLT) of the B-CLL according to the amount of the antigens for CD 5 and CD 20. Within the B-CLL patient population, no relation of progression of the disease with distribution of these antigens could be observed. In one patient the extraordinary phenotype CD 20+, CD 11+, leu 8+, CD 5- of the malignant lymphocytes was observed. An experimentally simple method to differentiate between the various chronic lymphocytic leukaemias (CLL) appeared to be the determination of orthogonal light scattering properties of lymphocytes. In healthy donors one can always distinguish two populations of lymphocytes in the orthogonal light scatter histograms. Lymphocytes of B-CLL patients show one uniform population with a relatively small orthogonal light scattering signal, lymphocytes of our patients with PLT of B-CLL or with LF-NHL show one uniform population with a relatively large orthogonal light scattering signal.

Clinical and immunological findings in large B-cell chronic lymphocytic leukemia

In order to define the characteristics of B-CLL cases in which the predominant cell population is composed of large lymphocytes, we studied 97 patients with B-CLL, comparing the cell morphological features with the clinical and biological findings and the immunological phenotype of the proliferating cells. Multivariant analysis showed that there were three significantly different morphological groups: Typical CLL, large lymphocyte CLL (LLL), and CLL with prolymphocytes (CLL/PL). The LLL group showed a greater incidence of lymphadenopathies (P less than 0.05) and higher percentages of both mu + delta + cells (P less than 0.01) and Fmc/7+ cells (P less than 0.001) than in typical CLL. The main differences between LLL and CLL/PL were the peripheral blood lymphocyte count and the percentage of Fmc/7+ cells (P less than 0.002)--both higher in the CLL/PL group--and the percentage of mouse rosette-forming cells (P less than 0.01)--lower in CLL/PL. Further studies including functional assays and survival analyses could contribute to elucidating whether these groups are different entities or a single disease with marked heterogeneity.

The importance of CD5-positive B cells in nonorgan-specific autoimmune diseases

CD5, the human counterpart of Ly-1 molecules in the mouse, are detectable but weakly expressed on a minute fraction of circulating B cells. The number of CD5-expressing B cells is increased in patients with rheumatoid arthritis or primary Sjögren's syndrome. These cells are similar to those leading to chronic lymphocytic leukemia (they may be induced to produce multispecific autoantibodies). Multispecific autoantibodies have also been described in the early B cell repertoire.

Analysis of T-cell-derived factors with the use of B-prolymphocytic leukemia cells

Mononuclear cells of five patients with B-prolymphocytic leukemia were tested for their functional capacities in vitro after stimulation. Leukemic B cells from these patients have a mature phenotypic marker profile and can be obtained in high numbers from peripheral blood. B cells of all five patients proliferated in response to phorbol myristate acetate. In one patient, this proliferation was strongly enhanced by the addition of T-cell-conditioned medium. Conditioned medium by itself or interleukin 2 in the presence or absence of the phorbol ester was not active. This enabled us to develop an assay for a B-cell growth factor different from interleukin 2. Next to their proliferative capacities, we found that malignant B cells of three of the five patients secreted large amounts of IgM when stimulated with pokeweed mitogen or interleukin 2 in the presence of allogeneic T cells. In the absence of these allogeneic cells, neither pokeweed mitogen nor interleukin 2 had any effect. However, T-cell-conditioned medium as well as the supernatants of two T-cell hybridomas induced strong IgM production in the absence of T cells. Thus, neoplastic B cells of some patients with B-prolymphocytic leukemia can be stimulated to proliferation and differentiation in vitro and can be used as an assay and model system to study the effect of T cells and/or T-cell factors in human B-cell activation.

Hairy cell leukemia

Hairy cell leukemia is a chronic lymphoproliferative disorder that has been recognized as a separate clinical pathologic entity for the last 25 years. After a decade of discussions about the origin of the neoplastic cell, it has now been well established that hairy cells represent a certain, rather mature stage of B-cell differentiation. Evidence for this has been derived from studies using immunophenotyping with monoclonal and polyclonal antibodies, cytochemistry, and immunoglobulin gene rearrangement. For many years, splenectomy was the only therapy of proven value in hairy cell leukemia. For patients who showed insufficient response to the operation, chemotherapy with low-dose alkylating agents was moderately successful, whereas polychemotherapy often resulted in excessive toxicity. More recently, therapy with alpha-interferon has been shown to be very promising, whereas deoxycoformicin may be an attractive alternative. These new advances in immunology and therapy are reviewed.

Intracellular immunoglobulin G 'pseudocrystals' in a patient with chronic B-cell leukemia

A patient with chronic B-cell leukemia in whom the malignant lymphocytes showed intracellular inclusions of immunoglobulin (Ig) G kappa molecules is described. Electron microscopy revealed filamentous material in the nuclear envelopes and in the cisternae of the rough endoplasmic reticulum. These in vivo surface Ig-negative, nonexcreting cells could be stimulated in vitro to excrete immunoglobulin-free light chain molecules into the supernatant, which were not found in the cytoplasm after stimulation.

Association of specific tyrosine phosphorylation with stages of B-cell differentiation in human lymphoid leukemias

In vitro protein phosphorylation in various types of human fresh lymphoid leukemic cells (C-ALL, B-CLL, HCL and PCL: B-cell lineage and T-ALL, ATL and T-CLL: T-cell lineage) were studied. In cases of B-CLL and HCL, tyrosine protein kinase (TPK) activity was at least 5-fold higher than that in other cases of B- and T-cell lineages. B-cell leukemic cells at various differentiation stages had different endogenous substrates in tyrosine phosphorylation as well as distinct TPK activity. The P-tyr-containing proteins of 68K, 59K and 56K were detected commonly in all the cases of B-cell lineage. The phosphorylated protein of 32K was present only in cases of PCL. On the other hand, in T-ALL and ATL, the major substrate in tyrosine phosphorylation was 58K. These results suggest that the characterization of in vitro tyrosine phosphorylation provides a new means not only to distinguish T- and B-lymphoid leukemia, but also to differentiate stages of lymphoid development.