Characterization of cells from invaded lymph nodes in patients with solid tumors. Lymphokine requirement for tumor-specific lymphoproliferative response.

The specific immune response against the malignant cells was investigated in patients with urinary bladder or larynx cancer. Lymphocytes from lymph nodes that drain the tumor site were tested for their proliferative and cytotoxic capacities against autologous malignant cells isolated from the primary tumor. In no occasion was a proliferative or a cytotoxic response observed. However, when the lymph node cell suspensions were depleted of cells expressing both OKM1 and Leu-7 markers by rosetting with the appropriate mAbs, a proliferative response could be observed. The lymphocytes responded to autologous tumor cells only if IL-2 was added to the cultures. IL-2 alone induced some cell proliferation, which was not, however, comparable to that observed in response to both IL-2 and tumor cells. A panel of allogeneic tumor cells consistently failed to stimulate OKM1-, Leu-7- cells in vitro. Response to autologous tumor cells was not caused by HLA-encoded molecules, as occurs in the autologous mixed lymphocyte reaction, since OKM1-, Leu-7- cells failed to be stimulated by autologous non-T cells. A proliferative response was observed only with cells from lymph nodes that had been classified as invaded by malignant cells according to histopathologic criteria. Cells from noninvaded lymph nodes consistently failed to respond. Cells stimulated with autologous tumor cells could be expanded in short-term lines by continuous addition of IL-2 and malignant cells. One of these lines, which comprised mainly T8+ cells, was stimulated to proliferate only by autologous tumor cells, and its proliferative response was inhibitable by anti-class I and not by anti-class II mAbs. This line showed lytic capacities against autologous malignant targets, while it was inefficient against all of the other allogeneic cells tested. In another set of experiments, the mechanisms whereby exogenous IL-2 had to be added to the cultures to sustain a proliferative response against neoplastic cells were investigated. When cocultured with autologous malignant cells, OKM1-, Leu-7- lymphocytes expressed IL-2 receptors, as could be assessed by anti-Tac fluorescent staining. Under these culture conditions, these cells did not produce IL-2, and no proliferation was observed. Addition of purified IL-1 to the cultures induced IL-2 production and cell proliferation. It is concluded that metastatic lymph nodes contain a T cell population that can be detected in a proliferative assay when both suppressor cells are removed and the appropriate molecular signals are supplied.

Interferon-gamma and IL-10 may protect from allergic polysensitization in children: preliminary evidence.

BACKGROUND: A functional defect of T regulatory cells (Treg) has been proposed as pathogenic mechanism of allergic reaction. Polysensitization is a common feature of allergic patients. AIM OF THE STUDY: It was to investigate the possible role of Treg-Th1 cytokines, in the development of new sensitizations in childhood. METHODS: Forty monosensitized (MS) children with allergic rhinitis were evaluated and followed-up for 2 years. New sensitizations were investigated. IL-10 and IFN-gamma were evaluated in in vitro experiments. RESULTS: Children remaining MS showed significant higher production of both IL-10 and IFN-gamma. CONCLUSION: This preliminary study provided evidence that IL-10 and IFN-gamma production could be defective in allergic children prone to develop polysensitization.

Long-term follow-up of neuroblastoma-associated opsoclonus-myoclonus-ataxia syndrome.

OBJECTIVE: The aim of this study is to describe the long-term neurological, neuropsychological and neuroradiological sequelae and to determine prognostic factors for neurological outcome in children with neuroblastoma-associated opsoclonus-myoclonus-ataxia (OMA) syndrome. METHODS: Data on medical history were collected for the study patients. Examinations with grading of neurological signs, neuropsychological tests and brain magnetic resonance imaging with spectroscopy were performed during a follow-up clinic. RESULTS: Fourteen subjects entered the study. All had localized neuroblastoma and they were evaluated after a median of 7.8 years. Patients with a chronic/multiphasic neurological course received steroids combined with intravenous immunoglobulins in the majority of cases. 71% presented neurological sequelae and 62% had a full-scale IQ below the normal range. All patients showed at least some deficit in the neuropsychological functions assessed (language, visual-motor integration, memory, attention and motor ability). Long-term deficits were more frequently detected in patients with an interval of more than 2 months between OMA onset and its diagnosis, even if in most comparisons statistical significance was not reached. Cerebellar atrophy, observed in 36% of patients, was not associated with the neurological outcome. CONCLUSIONS: Persisting disability is present in most children with neuroblastoma-associated OMA. However, our results support the role of an early diagnosis of OMA in reducing sequelae and encourage the use of new immunosuppressive therapies.

Functional insights into nucleotide-metabolizing ectoenzymes expressed by bone marrow-resident cells in patients with multiple myeloma.

Human myeloma cells grow in a hypoxic acidic niche in the bone marrow. Cross talk among cellular components of this closed niche generates extracellular adenosine, which promotes tumor cell survival. This is achieved through the binding of adenosine to purinergic receptors into complexes that function as an autocrine/paracrine signal factor with immune regulatory activities that i) down-regulate the functions of most immune effector cells and ii) enhance the activity of cells that suppress anti-tumor immune responses, thus facilitating the escape of malignant myeloma cells from immune surveillance. Here we review recent findings confirming that the dominant phenotype for survival of tumor cells is that where the malignant cells have been metabolically reprogrammed for the generation of lactic acidosis in the bone marrow niche. Adenosine triphosphate and nicotinamide-adenine dinucleotide extruded from tumor cells, along with cyclic adenosine monophosphate, are the main intracellular energetic/messenger molecules that serve as leading substrates in the extracellular space for membrane-bound ectonucleotidases metabolizing purine nucleotides to signaling adenosine. Within this mechanistic framework, the adenosinergic substrate conversion can vary significantly according to the metabolic environment. Indeed, the neoplastic expansion of plasma cells exploits both enzymatic networks and hypoxic acidic conditions for migrating and homing to a protected niche and for evading the immune response. The expression of multiple specific adenosine receptors in the niche completes the profile of a complex regulatory framework whose signals modify multiple myeloma and host immune responses.

Microvesicles released from multiple myeloma cells are equipped with ectoenzymes belonging to canonical and non-canonical adenosinergic pathways and produce adenosine from ATP and NAD.

Multiple myeloma (MM) derives from malignant transformation of plasma cells (PC), which accumulate in the bone marrow (BM), where microenvironment supports tumor growth and inhibits anti-tumor immune responses. Adenosine (ADO), an immunosuppressive molecule, is produced within MM patients' BM by adenosinergic ectoenzymes, starting from ATP (CD39/CD73) or NAD+ [CD38/CD203a(PC-1)/CD73]. These ectoenzymes form a discontinuous network expressed by different BM cells. We investigated the expression and function of ectoenzymes on microvesicles (MVs) isolated from BM plasma samples of patients with MM, using asymptomatic forms of monoclonal gammopathy of undetermined significance (MGUS) and smoldering MM (SMM) as controls. The percentage of MVs expressing ectoenzymes at high levels was higher when derived from MM patients than controls. BM CD138+ PC from MM patients expressed high levels of all ectoenzymes. Paired MVs samples confirmed a higher percentage of MVs with high ectoenzymes expression in MM patients than controls. Pooled MVs from MM patients or controls were tested for ADO production. The catabolism of ATP, NAD+, ADPR and AMP to ADO was higher in MVs from MM patients than in those from controls. In conclusion, our results confirmed the hypothesis that MVs in MM niche are main contributor of ADO production. The ability of MVs to reach biological fluids strongly support the view that MVs may assume diagnostic and pathogenetic roles.

Lymphoproliferative disorders and chemokines.

Chemokines are low molecular weight cytokines specialized in leukocyte recruitment. Recent studies have shown that tumor cells of hematopoietic and non hematopoietic origin express different chemokine receptors that may be involved in neoplastic cell growth, metastasis and angiogenesis. Human lymphoproliferative disorders arise from the malignant transformation of normal lymphoid cells frozen at discrete maturational stages. Studies performed with acute or chronic lymphoproliferative disorders have shown that CXCR4, the unique receptor for CXCL12, is up-regulated in many B and T cells malignancies and may be involved in metastatic localization of the neoplastic elements. Additional chemokine receptors are expressed in the individual lymphoproliferative disorders, but some of these are often non functional. Here we shall review the state of the art on chemokine receptor expression and function in human lymphoproliferative disorders, stressing the potential value of chemokines receptors as novel therapeutic targets. In this respect, small antagonistic peptides are being produced by pharmaceutical companies and hold great promise for clinical application.

Catastrophic relapse of Evans syndrome five years after allogeneic BMT notwithstanding full donor chimerism. Terminal hemolytic-uremic syndrome.

A patient with severe Evans syndrome received an allo-BMT from his HLA-identical sister on November, 2000. Full marrow and blood donor chimerism were achieved only after 5 donor lymphocyte infusions (DLI), and coincided with complete clinical remission and disappearence of auto-antibodies. Five years later, hemolytic anemia recurred with rapid increase of serum bilirubin to over 50 mg%: he responded to combined therapy, but died on day +17 from admission of an acute hemolytic uremic syndrome (HUS). All circulating blood cells, including erythrocytes, were 100% donor. Ex vivo cultured and expanded T and B cells from the peripheral blood were also 100% donor. The supernatants from B cell cultures, containing either IgM or IgG, did not react with a panel of erythrocytes. Thus in this typical autoimmune disease with a predominant B cell pathogenesis the donor immune system resulted "innocent of autoimmunity". The persistence of long-lived recipient autoreactive plasma-cell lines in survival niches, still producing autoantibodies, may be hypothesized for this and similar cases. The postulated graft-versus-autoimmunity (GVA) effect was apparently not sufficient to eradicate autoimmunity in this patient.

Phytohemagglutinin or pokeweed mitogen induction of in vitro colony formation by T-cells from patients with chronic lymphocytic leukemia.

The colony-forming capacity of peripheral blood T-cells isolated from B-cell chronic lymphocytic leukemia patients was studied and compared with that of peripheral blood T-cells isolated from 2 groups of normal controls (young and aged healthy donors). Upon stimulation with phytohemagglutinin or pokeweed mitogen. T-cells from both the patients and the controls developed into colonies but only in the presence of the appropriate conditioned media. When the responses of the 3 groups were compared, no statistically significant differences were detected. However, the number of patients who failed to respond to phytohemagglutinin was larger than that of normal controls. Studies on a selected group of patients demonstrated that such unresponsiveness was unrelated to the presence of suppressor cells or to inadequate conditions used for stimulation in culture. Rather, this unresponsiveness may be connected with an intrinsic T-cell defect present in certain B-cell chronic lymphocytic leukemia patients.

Stromal cell-derived factor-1 as a chemoattractant for follicular center lymphoma B cells.

BACKGROUND: Follicular center lymphoma displays widespread lymph node involvement at diagnosis. The chemoattractants that control the locomotion of follicular center lymphoma B cells have not been established. Stromal cell-derived factor-1 (SDF-1) is a CXC-class chemokine that enhances the migration of normal human B cells and is expressed in peripheral lymphoid tissues. Here we have investigated 1) whether SDF-1 stimulates the in vitro locomotion of follicular center lymphoma B cells and of their presumed normal counterparts (i. e., germinal center B cells) and 2) whether the same cells express SDF-1 transcripts. METHODS: B cells were purified by immunomagnetic bead manipulation. Messenger RNA was detected by reverse transcription-polymerase chain reaction. Migration was assessed by the filter and collagen invasion assays. All P values were two sided. RESULTS: Follicular center lymphoma B lymphocytes showed a statistically significant migratory response to 300 ng/mL SDF-1, both in the filter and in the collagen assays (P =.002 for each). Such response was mediated by the SDF-1 receptor, CXCR4. CD40 monoclonal antibody (MAb) and tonsillar germinal center B cells treated with CD40 MAb and recombinant interleukin 4, but not freshly isolated, migrated statistically significantly faster in the presence than in the absence of SDF-1 (P =.002 in both filter and collagen assays). Freshly isolated follicular center lymphoma and germinal center B cells expressed SDF-1 transcripts. CONCLUSIONS: This study shows that SDF-1 substantially enhances the migration of follicular center lymphoma B cells but not the migration of freshly purified germinal center B cells. This difference may be related to the extended survival of follicular center lymphoma versus germinal center B cells. SDF-1 produced in follicular center lymphoma lymph nodes may play a role in the local dissemination of tumor cells.

Presence of activated T-cells with a T8+ M1+ Leu 7+ surface phenotype in invaded lymph nodes from patients with solid tumors.

The lymphocyte surface phenotype of lymph nodes from patients with larynx or urinary bladder carcinoma was investigated by using a panel of monoclonal antibodies. The phenotype pattern of lymphocytes from lymph nodes invaded by malignant cells (as assessed by histopathology) was different from that of the cells from noninvaded or normal control nodes. Although the proportion of natural killer cells or macrophages was similar in the 3 groups of lymph nodes, invaded lymph nodes contained a higher proportion of T-cells and a lower B-cell percentage. Furthermore, cells from invaded nodes comprised 15-20% of T3+ T8+ cells that coexpressed the M1 marker and, to some extent, also the Leu 7 marker. A large proportion of cells with multiple markers were activated, as shown by the expression of Tac and HLA-DR antigens. In 2 patients activated T8+ cells expressing also M1 and Leu 7 markers infiltrated the tumor site. The presence of these activated cells both in involved nodes and tumor mass may indicate that they originate in response to cancer.

Cytokine gene expression in neoplastic B cells from human mantle cell, follicular, and marginal zone lymphomas and in their postulated normal counterparts.

Cytokines may promote tumor growth by paracrine and/or autocrine pathways. Little information is available because malignant cells differ from their normal counterparts for the cytokine repertoire they express. Here we have investigated by reverse transcription-PCR the expression of 22 cytokine genes in neoplastic B lymphocytes from six patients with mantle cell lymphoma, 10 with follicular lymphoma, and 5 with marginal zone lymphoma and in their normal counterparts, i.e., naive, germinal center, and memory B cells, purified from tonsils. The overall profiles of cytokine gene expression in neoplastic B cells and in the corresponding normal B-cell subsets were similar, but some "holes" in the repertoire of malignant versus normal B lymphocytes were detected. Different "hole" combinations were identified consistently in mantle cell lymphoma, follicular lymphoma, and marginal zone lymphoma, thus representing molecular fingerprints of each individual lymphoma entity.

Differential effects of N-(4-hydroxyphenyl)retinamide and retinoic acid on neuroblastoma cells: apoptosis versus differentiation.

Retinoids exert various important biological effects in the control of normal growth, differentiation, and fetal development. While retinoic acid (RA) has entered clinical trials as a differentiation-promoting agent, it is only recently that the synthetic retinoid N-(4-hydroxyphenyl)retinamide (HPR) has been shown to be of potential clinical interest in cancer chemoprevention and treatment. Since thus far no data exist on the effects of HPR on neural crest cell-derived tumors, we have examined its in vitro effects on neuroblastoma (NB) cell lines and found that at relevant pharmacological concentrations it induces a dose-dependent growth inhibition. The antiproliferative effects of HPR were, in six of six cell lines tested, drastically more potent that those induced by an equimolar dose of RA. Time course growth analysis showed that HPR at 3 x 10(-6) M induces a very rapid (24-72 h) fall in thymidine uptake (> 90%), whereas at 3 x 10(-7) M it exhibits cytostatic effects. In contrast to RA, HPR did not show morphological changes typical of NB cell maturation nor did it induce the expression of any cytoskeletal protein associated with neuronal differentiation. DNA flow cytofluorimetric analysis revealed that HPR did not induce an arrest in a specific phase of the cell cycle while triggering apoptosis. This phenomenon was evidenced both by the visualization of "DNA ladders" on gel electrophoresis and by a quantitative assay for evaluating programmed cell death based upon the labeling of DNA breaks with tritiated thymidine. With the latter method, apoptotic cells were detectable as early as 3-6 h after treatment of NB cells with 10(-5) M HPR, while more than 50% of cells were apoptotic by 24-72 h following exposure to 3 x 10(-6) M HPR. In contrast, RA induced a low rate of apoptosis in NB cells only after 3-5 days. Time lapse photomicroscopy showed that NB cells treated with HPR underwent a death process highly reminiscent of apoptosis, with progressive condensation of the cytoplasm around the nucleus and intense cell shrinkage. The cells then rounded up and detached from the plate. Furthermore, propidium iodide staining of the DNA showed that a high proportion of cells treated with HPR displayed a small and brightly staining nucleus; chromatin appeared aggregated into dense masses in the nuclear periphery, a typical feature of apoptotic cells. In conclusion, our study demonstrates that contrary to the differentiation-promoting activity of RA, HPR dramatically suppresses NB cell growth by inducing programmed cell death.(ABSTRACT TRUNCATED AT 400 WORDS)

Restricted ROC curves are useful tools to evaluate the performance of tumour markers.

In Clinical Epidemiology, receiver operating characteristic (ROC) analysis is a standard approach for the evaluation of the performance of diagnostic tests for binary classification based on a tumour marker distribution. The area under a ROC curve is a popular indicator of test accuracy, but its use has been questioned when the curve is asymmetric. This situation often happens when the marker concentrations overlap in the two groups under study in the range of low specificity, corresponding to a subset of values useless for classification purposes (non-informative values). The partial area under the curve at a high specificity threshold has been proposed as an alternative, but a method to identify an optimal cut-off that separates informative from non-informative values is not yet available. In this study, a new statistical approach is proposed to perform this task. Furthermore, a statistical test associated with the area under a ROC curve corresponding to informative values only (restricted ROC curve) is provided and its properties are explored by extensive simulations. Finally, the proposed method is applied to a real data set containing peripheral blood levels of six tumour markers proposed for the diagnosis of neuroblastoma. A new approach to combine couples of markers for classification purposes is also illustrated.

PHA-induced human T cell colony formation: enhancing effect of large granular lymphocytes.

The capacity of phytohemagglutinin (PHA)-stimulated human T cells to develop into colonies in agar has been evaluated in the presence or absence of a variety of peripheral blood mononuclear cell subsets. A subpopulation of non-T, non-B cells with receptors for the Fc portion of IgG (i.e. third population cells or TPC) was found to enhance considerably the T cell colony forming capacity. Since TPC have been previously shown to be highly enriched for large granular lymphocytes (LGL, i.e. cells with cytoplasmic azurophilic granules and acid hydrolases), LGL were purified on Percoll density gradients and tested for their T cell colony enhancing capacity. It was shown that LGL were indeed the cells capable of enhancing the T cell colony formation.

The P2X7 receptor is a key modulator of the PI3K/GSK3ß/VEGF signaling network: evidence in experimental neuroblastoma.

Neuroblastoma (NB) is an aggressive pediatric tumor, responsible for 15% of cancer-related deaths in childhood, lacking an effective treatment in its advanced stages. The P2X7 receptor for extracellular ATP was associated to NB cell proliferation and recently emerged as a promoter of tumor engraftment, growth and vascularization. In an effort to identify new therapeutic options for neuroblastoma, we studied the role of P2X7 receptor in NB biology. We first analyzed the effect of P2X7 activation or down-modulation of the main biochemical ways involved in NB progression: the PI3K/Akt/GSK3ß/MYCN and the HIF1α/VEGF pathways. In ACN human NB cells, P2X7 stimulation enhanced PI3K/Akt, while decreasing GSK3ß activity. In the same model, P2X7 silencing or antagonist administration reduced the activity of PI3K/Akt and increased that of GSK3ß, leading to a decrease in cellular glycogen stores. Similarly, P2X7 downmodulation caused a reduction in HIF1α levels and vascular endothelial growth factor (VEGF) secretion. Systemic administration of two different P2X7 antagonists (AZ10606120 or A740003) in nude/nude mice reduced ACN-derived tumor growth. An even stronger effect of P2X7 blockade was obtained in a syngeneic immune-competent neuroblastoma model: Neuro2A cells injected in AlbinoJ mice. Together with tumor regression, treatment with P2X7 antagonists caused downmodulation of the Akt/HIF1α axis, leading to reduced VEGF content and decreased vessel formation. Interestingly, in both experimental models, P2X7 antagonists strongly reduced the expression of the probably best-accepted oncogene in NB: MYCN. Finally, we associated P2X7 overexpression with poor prognosis in advanced-stage NB patients. Taken together, our data suggest that P2X7 receptor is an upstream regulator of the main signaling pathways involved in NB growth, metabolic activity and angiogenesis, and a promising therapeutic target for neuroblastoma treatment.

The interleukin (IL)-31/IL-31R axis contributes to tumor growth in human follicular lymphoma.

Interleukin (IL)-31A binds to an heterodimer composed of IL-31 receptor A (IL-31RA) and Oncostatin M Receptor (OSMR). The IL-31/IL-31R complex is involved in the pathogenesis of various skin diseases, including cutaneous T-cell lymphoma. No information is available on the relations between the IL-31/IL-31R complex and B-cell lymphoma. Here we have addressed this issue in follicular lymphoma (FL), a prototypic germinal center(GC)-derived B-cell malignancy. IL-31 enhanced primary FL cell proliferation through IL-31R-driven signal transducer and activator of transcription factor 1/3 (STAT1/3), extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt phosphorylation. In contrast, GC B cells did not signal to IL-31 in spite of IL-31R expression. GC B cells expressed predominantly the inhibitory short IL-31RA isoform, whereas FL cells expressed predominantly the long signaling isoform. Moreover, GC B cells lacked expression of other IL-31RA isoforms potentially involved in the signaling pathway. IL-31 protein expression was significantly higher in surface membrane than in cytosol of both FL and GC B cells. IL-31 was detected in plasma membrane microvesicles from both cell types but not released in soluble form in culture supernatants. IL-31 and IL-31RA expression was higher in lymph nodes from FL patients with grade IIIa compared with grade I/II, suggesting a paracrine and/or autocrine role of IL-31/IL-31RA complex in tumor progression through microvesicle shedding.

Characterization and tumorigenicity of human neuroblastoma cells transfected with the IL-2 gene.

Immunization of cancer patients with cytokine-engineered tumor cells is being currently tested in several trials. To test the feasibility of this approach in neuroblastoma (NB) patients we investigated the functional consequences of interleukin-2 (IL-2) gene transfer into NB cell lines. Two human NB cell lines were transfected with the plasmid expression vector RSV.5neo containing the human IL-2 cDNA, and their tumorigenicity was evaluated in a nude mice xenograft model after characterization of the growth patterns and phenotypic features in vitro. The combination of IL-2 gene transfection and the xenograft model in nude mice was chosen on the basis of the low or absent expression of HLA class I antigen in human NB tumors. Our aim was to evaluate the effectiveness of an immunization protocol that could elicit a nonspecific antitumor response. The IL-2 stable transfectants were morphologically identical to parental or vector-transfected cells but completely lost tumorigenicity and inhibited, through a bystander effect, the growth of parental cells injected simultaneously at the same site. Histologic and immunohistochemical analysis of the nodules showed extensive necrosis with severe endothelial damage. The infiltrating cells were mainly macrophages, while natural killer (NK) cells were scarce. However, depletion of NK cells by anti-CD122 monoclonal antibody indicated that the rejection process required NK cell activity. The relevance of these data for the development of therapeutic approaches using cytokine-engineered NB cell lines is discussed.

Accelerated chemotherapy with or without GM-CSF for small cell lung cancer: a non-randomised pilot study.

Two series of five consecutive patients with small cell lung cancer were treated with an "accelerated" chemotherapy regimen of cyclophosphamide-doxorubicin-vincristine (CAV) and cisplatin-etoposide (PE) alternated possibly every week. In the first group of patients (median age 49 years, range 46-52) recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) was given as soon as grade IV leukopenia occurred, while in the second group (median age 59 years, 55-68) no growth factor was administered. The mean interval between chemotherapy courses and the mean duration of chemotherapy were 10 and 57 days, respectively, in the patients supported with GM-CSF compared with 13 and 72 days in the control group. One GM-CSF treated patient was withdrawn after the third cycle because of severe toxicity. The mean white blood cell and platelet nadirs were 600 and 46,000/microliters in the first group vs. 840 and 105,000/microliters in the controls. Overall chemotherapy dose-intensity was increased by two fold in the patients given GM-CSF compared with a 1.5 fold increase in the control patients. In all cases, irrespective of their treatment, there was an impaired colony forming capacity of circulating and marrow haemopoietic progenitor cells when grade IV leukopenia occurred, with recovery after the end of leukopenia. This pilot study suggests that accelerated CAV/PE chemotherapy is feasible both with and without GM-CSF. Different GM-CSF schedules as well as combinations of different haemopoietic growth factors may further improve dose-intensity.

Immunoreactive lactoferrin in resting, activated, and neoplastic lymphocytes.

Lactoferrin (Lf) in lymphocytes was assessed with immunofluorescence/flow cytometric technique. Surface Lf was detected primarily among B-cell-enriched preparations. Tonsillar B-cells of different densities expressed surface Lf similarly. Very small percentages of CALLA+ ALL, HCL, or EBV-transformed B-cells expressed surface Lf, whereas B-CLL lymphocytes had the highest percentages of surface Lf positivity. Few resting, cultured, or neoplastic T-lymphocytes expressed Lf. The pattern of immunofluorescence and analyses of surface and total cellular immunoreactive Lf indicated that Lf is associated primarily with the lymphocyte surface. The percentage and/or intensity of surface Lf-specific fluorescence were not significantly altered in B- or T-cells by incubation with physiologic concentrations of differric Lf, and the percentages of Lf-positive cells detected in respective subjects remained stable over time. Surface Lf positivity was unrelated to the expression of other surface antigens (except those marking B- or T-cell lineage) or cell cycle. Expression and/or binding of Lf in B-lymphocytes may become increased during certain stages of cell maturation.

Late graft failure 8 years after first bone marrow transplantation for severe acquired aplastic anemia.

A 14-year-old patient with acquired very severe aplastic anemia (VSAA) underwent bone marrow transplantation (BMT) from his HLA-identical brother. Preparative therapy was cyclophosphamide (CY) 200 mg/kg over 4 days. GVHD prophylaxis was with cyclosporin A (CsA) for a year. After an 8 year follow-up during which the patient was well with normal blood counts, graft failure occurred. At this time marrow chimerism studies demonstrated that 85% of hemopoiesis was of recipient origin. The patient was re-engrafted from the same donor after conditioning with CY 200 mg/kg over 4 days plus rabbit antithymocyte globulin (ATG) 3.5 mg/kg/day for 3 days. After 140 days follow-up he has a normal blood count. The possible causes of the graft failure are discussed. This case demonstrates that, although rarely, very late graft failure may occur after BMT for AA and highlights the need for long-term monitoring even in apparently successfully transplanted patients.