Impact of the COVID-19 pandemic on the activity of the Radiological Emergency Department: the experience of the Maggiore della Carità Hospital in Novara.

PURPOSE: During the first peak of the COVID-19 pandemic, the activity of Emergency Departments worldwide changed dramatically, focusing on diagnosis and care of the Sars-Cov-2 associated disease. These major changes also involved the activity of the Emergency Radiology Department (ERD). This study aimed to analyse the impact of the COVID-19 pandemic on imaging studies, both in terms of the amount, frequency and subspecialty of different imaging modalities requested to the ERD of the Maggiore della Carità Hospital in Novara (Italy). METHODS: To this end, our observational study took into account the imaging studies requested by the emergency department during three-time spans. These were defined as phase 0 (pre-pandemic), phase 1 (pandemic peak with complete lockdown) and phase 2 (post-pandemic peak with partial lifting of restrictive measures), as derived from Italian urgent decrees by the President of the Council of Ministers (DPCM) which established the duration and entity of the lockdown measures throughout the pandemic. The dataset was processed and then compared with Pearson's chi-squared test. RESULTS: During the pandemic peak, our data showed a significant drop in the total number of studies requested and a significant rise in computed tomography (CT) studies. In particular, a statistically significant increase in chest CT studies was found, probably due to the high sensitivity of this imaging method in identifying pulmonary involvement during respiratory tract infection of possible viral etiology (SARS-Cov-2). Moreover, we observed a statistically significant decrease of X-ray (XR) and ultrasound (US) studies during phase 1 compared to phase 0 and phase 2 probably due to a reduction in the numbers of ER visits for minor traumas given the mobility restrictions and people hesitancy in visiting the ER due to fear of contagion. CONCLUSIONS: We can conclude that the activity of the ERD was heavily impacted by the SARS-Cov-2 pandemic. Further studies will be needed to estimate the impact of the pandemic on public health in terms of excess mortality related to delayed diagnosis and care of non-COVID diseases.

Association between red cell distribution width and response to methotrexate in rheumatoid arthritis.

Red cell distribution width (RDW) is an unconventional biomarker of inflammation. We aimed to explore its role as a predictor of treatment response in rheumatoid arthritis (RA). Eighty-two RA patients (55 females), median age [interquartile range] 63 years [52-69], were selected by scanning the medical records of a rheumatology clinic, to analyze the associations between baseline RDW, disease activity scores and inflammatory markers, as well as the relationship between RDW changes following methotrexate (MTX) and treatment response. The lower the median baseline RDW, the greater were the chances of a positive EULAR response at three months, 13.5% [13.0-14.4] being among those with good response, vs 14.0% [13.2-14.7] and 14.2% [13.5- 16.0] (p=0.009) among those with moderate and poor response, respectively. MTX treatment was followed by a significant RDW increase (p<0.0001). The increase of RDW was greater among patients with good EULAR response, becoming progressively smaller in cases with moderate and poor response (1.0% [0.4-1.4] vs. 0.7 [0.1-2.0] vs. 0.3 [-0.1-0.8]; p=0.03). RDW is a strong predictor of early response to MTX in RA. RDW significantly increases after MTX initiation in parallel to treatment response, suggesting a role as a marker of MTX effectiveness.

Growth arrest specific gene 6 protein concentration in cerebrospinal fluid correlates with relapse severity in multiple sclerosis.

BACKGROUND: Growth arrest specific gene 6 (Gas6) protein enhances survival of oligodendrocytes and neurons, and it is involved in autoimmunity. Therefore, we aimed to verify whether cerebrospinal-fluid (CSF) Gas6 concentration may represent a biomarker of disease activity in multiple sclerosis. METHODS: Sixty-five patients who underwent a spinal tap during relapse of relapsing/remitting multiple sclerosis (RR-MS)(McDonald-criteria) were studied. Forty patients affected by noninflammatory/nonautoimmune neurological diseases served as controls. Relapse was defined according to Schumacher criteria. Symptoms were grouped according to Kurtzke-Functional System (FS). Clinical characteristics of the relapse, duration, Expanded-Disability-Status Scale (EDSS) change, number of FS involved, completeness of recovery, age, steroid therapy, were categorised. Patients were followed at 6-month intervals to assess relapse rate and EDSS progression. Gas6 was measured (CSF, plasma) by in-house-enzyme-linked immunoassay (ELISA). RESULTS: Higher CSF Gas6 concentrations were observed in relapses lasting ≤60 days (8.7 ± 3.9 ng/mL) versus >60 days (6.5 ± 2.6) or controls (6.5 ± 2.4; P = 0.05), with ≤2 FS involved (8.5 ± 3.8) versus >2 FS (5.6 ± 2.5) (P < 0.05) and EDSS change ≤2.5 points (8.8 ± 3.7) versus >2.5 (6.5 ± 3.5) (P = 0.04). Conversely, CSF Gas6 was not predictive of the completeness of recovery. Plasma and CSF concentrations were not related (R (2) = 0.0003), and neither were predictive of relapse rate or EDSS progression after first relapse. CONCLUSIONS: CSF concentration of Gas6 is inversely correlated with the severity of relapse in RR-MS patients but does not predict the subsequent course of the disease.

Suspected acute allergic reactions: analysis of admissions to the Emergency Department of the AOU Maggiore della Carità Hospital in Novara from 2003 to 2007.

OBJECTIVE OF THE STUDY: The aim of our work is to ascertain the frequency and the impact of acute allergic reactions on the routine of a highly-specialized Emergency Department collecting information on the admission, the typology of symptoms and the degree of severity calculating the incidence and the outcomes of the events. MATERIALS AND METHODS: The study started the 1 July 2006 and the records of the Emergency Department of the Maggiore della Carità Hospital in Novara were consulted retrospectively in the period between the 1 January 2003 and the 31 December 2006, and prospectively up to the 31 December 2007, using keywords that could identify admission for suspected allergic reactions. Information relating to internal medicine and/or pediatric cases were examined, excluding all surgical and/or trauma cases. The number ofadmissions per year was considered broken down by clinical signs, triage assessment upon admission and discharge outcome. RESULTS: Admissions to the Emergency Department during the period under consideration were 165,120 with 6107 suspected cases of allergic reactions. The symptoms most frequently reported both in adults (A) and children (C < or =18 years old), were: hives 37%, asthma 20.65 (A)% and 27.4% (C); drug allergy 7.5% (A) and 6.1% (C). Reactions to Hymenoptera venom were less frequent, 4.7% (A) and 1.27% (C); the frequency of angioedema, conjunctivitis and rhinitis was between 1 and 4%. The incidence of food allergies (1.4%) and anaphylaxis (0.8%) was comparable for all ages. The triage assessment showed a significant percentage of "yellow" and "red" codes, with 362 cases (5.9%) and 71 cases (1.16%) respectively. A total of 151 patients was hospitalized, no one classified as "white" code. Death occurred in 7 cases: 4 "yellow" codes and 3 "red" codes, respectively. A more detailed specialistic evaluation was recommended in only 10% of the patients. CONCLUSIONS: Admissions to the Emergency Department for suspected allergic reaction are proportional to the number of overall admissions for internal medicine cases and do not appear to be related to the general increase of allergies in the population. This led us to focus our attention on how allergic diseases impact the work of an Emergency Department and how to describe the discharge diagnosis better. A significant number of descriptive diagnoses also turned out to be inaccurate and did not allow the syndrome to be identified properly. The analysis of this information aims to be a stimulus to improve the emergency clinical approach used for allergic diseases and to plan the adequate management ofallergic patients after they have been treated in hospital.

Alpha-linolenic acid and cardiovascular diseases omega-3 fatty acids beyond eicosapentaenoic acid and docosahexaenoic acid.

Over the last decades, an increasing body of evidence has been accumulated on the beneficial effect of polyunsaturated fatty acids both in primary and secondary prevention of cardiovascular diseases. However, the vast majority of the studies has been performed on long-chain polyunsaturated fatty acids, such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and not on their biochemical precursor, alpha-linolenic acid (ALA). Actually, ALA has some other beneficial effects apart from the known antiarrhythmic effect. In fact, ALA has a strong inhibitory effect on omega-6 metabolic pathway. An adequate daily intake of ALA shifts metabolic pathway to EPA, so favoring the formation of products with a predominant antiaggregating and vasorelaxing action, with respect to eicosanoids with a predominant thrombotic effect. Some important evidences have been raised on the association between ALA and cardiovascular mortality. Indeed, dietary ALA has been associated with a lower rate of fatal and nonfatal coronary events. Hence, major scientific associations published nutritional guidelines including a specific recommendation for ALA.

Remission of refractory lupus nephritis with a protocol including rituximab.

Immunosuppression with corticosteroids and cyclophosphamide is the standard of care for lupus nephritis. We report a 19-year old woman with lupus nephritis and nephrotic syndrome who had not achieved complete remission after treatment with 15.7 g cyclophosphamide and 13.7 g prednisone. We planned a consolidation phase with: 1) cyclophosphamide 20 mg/kg i.v. every 28 days for three cycles; 2) anti-CD20 chimeric monoclonal antibody (rituximab) 375 mg/m2 i.v. weekly for four weeks; and 3) slow tapering of prednisone p.o., q.o.d., after a reinduction dose during rituximab administration. At the end of this phase the patient achieved complete remission. An indefinite maintenance treatment with methotrexate, cyclosporin and low-dose prednisone was then started. Twenty-four months later the patient remains in remission. In the immunosuppressive treatment of lupus nephritis the insertion of a consolidation phase with rituximab combined with cyclophosphamide achieves a therapeutically important and lasting deletion of the lymphocyte clone responsible for autoimmunity.

Acute megakaryoblastic leukemia: experience of GIMEMA trials.

The objective of the study was to evaluate the incidence, characteristics, treatment and outcome of acute megakaryoblastic leukemia (AMeL) in patients enrolled in GIMEMA trials. Between 1982 and 1999, 3603 new consecutive cases of AML aged over 15 years were admitted to GIMEMA trials. Of them, 24 were AMeL. The incidence of AMeL among AML patients enrolled in GIMEMA trials was 0.6% (24/3603). Diagnosis was based on morphological criteria. Out of 11 cytogenetic studies performed two presented chromosome 3 abnormalities. Twelve patients (50%) reached a CR, five (21%) died in induction and seven (27%) were unresponsive. The median duration of CR was 35 weeks (range 10-441). Seven patients underwent transplantation procedures (1 BMT, 4 aBMT, 2 aPBSCT). Four patients died in CR due to chemotherapy-related complications. Comparing the CR rate between AMeL and the other cases of AML enrolled in GIMEMA trials, no differences were observed. These results were mirrored for different age groups. The median survival was 40 weeks. At present, after a follow-up of a minimum of 2 years, only two patients are alive in CR, all the others having died. A 5-year Kaplan-Meier curve shows a disease-free survival of 17% and an actuarial overall survival of 10%. AMeL is a rare form of AML. The CR duration and the overall survival in this group of patients are very poor, even if similar to those observed in other AML. Furthermore, a high number of deaths in CR were observed. On the basis of these data, a specific therapeutic approach, possibly with innovative treatments, should be evaluated.

Making, disseminating and using clinical guidelines.

Clinical guidelines are statements designed to help physicians make decisions about appropriate health care for specific circumstances. The constant rise in the number of published guidelines has been accelerated by the need of healthcare organizations to integrate evidence from clinical research with rational health policy, with the prospect of improving the quality and reducing the costs of health care at a local level. The best guidelines are developed from a systematic examination and appraisal of good evidence from well conducted trials, supported by appropriate clinical expertise, and leading to unambiguous recommendations. Great care needs to be taken both to maximize the validity of guidelines and to ensure their use within clinical practice. Moreover, the evidence on which clinical guidelines are based can change with time and therefore they should be reviewed regularly. The critical approaches to making high-quality guidelines, the value of implementation strategies, and how healthcare organizations and individual physicians can use medical guidelines to enhance clinical effectiveness will be discussed.

[Tetanus prophylaxis. Proposed rationalization of procedure in the occupational field]. / Profilassi antitetanica. Proposta di razionalizzazione delle procedure in ambito occupazionale.

After a recent increase in cases of tetanus in Italy, the Ministry of Health has proposed vaccination of the entire population, inviting local physicians to cooperate towards this end. The author suggests periodic dosage of tetanus antitoxin antibodies as the most economic and efficient method of identifying workers who are not protected by vaccination.

Molecular characterization of HHV-8 positive primary effusion lymphoma reveals pathogenetic and histogenetic features of the disease.

BACKGROUND: Primary effusion lymphoma (PEL) associates with HHV-8 infection, preferentially develops in immunodeficient patients and grows in the serous body cavities. PEL derives from post-germinal center, pre-terminally differentiated B-cells. The pathogenesis of PEL is unclear and the sole identified genetic lesions are human herpesvirus type-8 (HHV-8) infection in all cases and EBV infection in 70% of cases. Epstein-Barr virus (EBV) infection in PEL displays a latency I phenotype. OBJECTIVES: To clarify the pathogenesis and histogenesis of PEL by investigating (1) the lymphoma karyotype; (2) the expression status of the Met tyrosine kinase receptor and of its ligand hepatocyte growth factor (HGF); (3) the molecular profile of EBV, with particular focus on mutations of EBNA-1 genes, which are thought to affect viral tumorigenicity in EBV-infected neoplasms displaying the latency I phenotype. STUDY DESIGN: Twenty-four PEL (nine cell lines and 15 primary specimens) formed the basis of the study. Karyotypes were investigated by conventional cytogenetics and fluorescent in situ hybridization (FISH) in selected cases. The expression status of Met and HGF was defined by multiple techniques, including RT-PCR, FACS analysis, immunocytochemistry, Western blot studies and ELISA. The molecular profile of EBNA-1 genes of EBV were investigated by DNA direct sequencing. RESULTS: Trisomy 7, trisomy 12 and breaks at 1q21-q25 are recurrently associated with PEL. PEL consistently co-express Met and HGF both at the mRNA and protein level. Among aggressive B-cell lymphomas, Met/HGF co-expression appears to be relatively specific for PEL. The EBNA-1 gene of EBV displays a high degree of genetic heterogeneity in PEL, with no preferential association with one specific variant. CONCLUSIONS: PEL associates with recurrent chromosomal alterations, suggesting that viral infection is not sufficient for tumor development and that lesions of cellular genes may be required. The expression of Met/HGF by PEL cells may bear implications for the lymphoma proliferation and growth pattern, since Met/HGF interactions influence cell mitogenesis and motogenesis. EBV infection in PEL displays a latency I phenotype and fails to associate with specific EBNA-1 variants, suggesting that the role of EBV in PEL is not mediated by the major transforming pathways currently known in EBV positive lymphomas.

The tyrosine kinase receptor met and its ligand HGF are co-expressed and functionally active in HHV-8 positive primary effusion lymphoma.

Primary effusion lymphoma (PEL) harbors consistent infection by human herpesvirus-8, preferentially develops in immunodeficient patients and selectively localizes to the serous body cavities. Histogenetic analysis has suggested that PEL originates from post-germinal center, pre-terminally differentiated B cells sharing phenotypic features with plasma cells. Here we have investigated the expression status and functional integrity of the Met tyrosine kinase receptor and of its ligand hepatocyte growth factor (HGF). Thirteen PEL (nine cell lines and four primary specimens) were analyzed for Met and HGF expression and function by multiple assays. For comparison, a panel of 34 high grade B cell non-Hodgkin lymphomas (NHL) other than PEL was also investigated. Co-expression of Met and HGF was found in all PEL analyzed, whereas it was restricted to 1/34 B cell NHL other than PEL (P < 0.001; chi2 test). The Met protein expressed by PEL displays biochemical characteristics typical of Met expressed by other cell types and is capable of tyrosine autophosphorylation. By using a combination of immunological and biological assays, production and secretion of a functional HGF species was identified in all PEL cell lines analyzed. HGF stimulation of PEL cells rapidly induces Met tyrosine phosphorylation, demonstrating the functional integrity of the Met/HGF loop. Because of the well known mitogenic and motogenic properties of Met/HGF interactions, these data may bear implications for PEL growth and dissemination. Among B cell neoplasms, Met/HGF co-expression selectively clusters with PEL and, as demonstrated by previous studies, with multiple myeloma plasma cells, thus reinforcing the notion that PEL displays biologic similarities with tumors derived from late stages of B cell differentiation.

Mutation of BAX occurs infrequently in acquired immunodeficiency syndrome-related non-Hodgkin's lymphomas.

Acquired immunodeficiency syndrome (AIDS)-related non-Hodgkin's lymphomas (AIDS-NHLs) consistently derive from B cells, are histologically heterogeneous, and are associated with distinct molecular pathways depending upon histology. Recently, it has been proposed that inactivating mutations of the bax death agonist may contribute to the pathogenesis of human tumors. In particular, among B-cell malignancies, BAX mutations have been detected at a certain frequency in Burkitt lymphomas. This study is aimed at defining the status of the BAX gene throughout the clinicopathologic spectrum of AIDS-NHL (n = 54), including AIDS-related Burkitt lymphoma (n = 14), AIDS-related Burkitt-like lymphoma (n = 8), AIDS-related diffuse large cell lymphoma (n = 15), AIDS-related primary central nervous system lymphoma (n = 6), and AIDS-related primary effusion lymphoma (n = 11). All 6 BAX exons and flanking sequences were subjected to mutational analysis by polymerase chain reaction-single strand conformation polymorphism followed by DNA direct sequencing of positive cases. Mutations of BAX among AIDS-NHL were restricted to a cell line of AIDS-related primary effusion lymphoma, which harbored a frameshift mutation causing the introduction of a proximal stop codon. All other AIDS-NHL displayed wild-type BAX alleles. In order to investigate whether BAX inactivation in AIDS-NHL may occur through mechanisms other than gene mutation, bax protein expression was investigated by Western blot analysis or immunohistochemistry in selected cases. All AIDS-NHL analyzed expressed normal bax proteins. Overall, this study indicates that deregulation of apoptotic control in AIDS-NHL is not caused by BAX alterations. Genes Chromosomes Cancer 27:177-182, 2000.

Hematopoietic growth factors in autologous transplantation.

Hematopoietic growth factors (HGFs) sustain the survival, proliferation and differentiation of hematopoietic stem cells and some functions of mature blood cells. In man several HGFs have been characterised and cloned so far, and this has allowed investigators to confer the rationale for the clinical application of these molecules in hematology and oncology. In particular G-CSF and GM-CSF are currently utilised to abrogate the hematological toxicity of chemotherapy for standard and dose-intensified therapy, neutropenia following bone marrow and peripheral blood stem cell transplantation. Moreover there has recently been great interest in the ex vivo expansion of hematopoietic stem and progenitor cells for a variety of applications, such as in vitro tumor cell purging or for reducing the volume of blood processed by the leukapheresis. Several combinations of HGFs have been described to sustain the ex vivo survival and proliferation of these cells disclosing new opportunities in the field of stem cells transplants.

GAS6 inhibits granulocyte adhesion to endothelial cells.

GAS6 is a ligand for the tyrosine kinase receptors Rse, Axl, and Mer, but its function is poorly understood. Previous studies reported that both GAS6 and Axl are expressed by vascular endothelial cells (EC), which play a key role in leukocyte extravasation into tissues during inflammation through adhesive interactions with these cells. The aim of this work was to evaluate the GAS6 effect on the adhesive function of EC. Treatment of EC with GAS6 significantly inhibited adhesion of polymorphonuclear cells (PMN) induced by phorbol 12-myristate 13-acetate (PMA), platelet-activating factor (PAF), thrombin, interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), but not that induced by FMLP and IL-8. GAS6 did not affect adhesion to resting EC. Titration experiments showed that high concentrations of GAS6 were needed to inhibit PMN adhesion and that inhibition was dose-dependent at the concentration range of 0.1 to 1 microg/mL. One possibility was that high concentrations were needed to overwhelm the effect of endogenous GAS6 produced by EC. In line with this possibility, treatment of resting EC with soluble Axl significantly potentiated PMN adhesion. Analysis of localization of GAS6 by confocal microscopy and cytofluorimetric analysis showed that it is concentrated along the plasma membrane in resting EC and treatment with PAF induces depletion and/or redistribution of the molecule. These data suggest that GAS6 functions as a physiologic antiinflammatory agent produced by resting EC and depleted when proinflammatory stimuli turn on the proadhesive machinery of EC.

4-Aminobiphenyl-DNA adducts and p53 mutations in bladder cancer.

Epidemiologic studies have suggested that smokers of air-cured tobacco (rich in arylamines) are at higher risk of bladder cancer than smokers of flue-cured tobacco. The risk has been shown to be modulated by the N-acetyltransferase genotype. We analyzed the biopsies of 45 patients with bladder cancer. p53 mutations were sought by direct sequencing, and 4-aminobiphenyl-DNA adducts were measured by negative ion gas chromatography-mass spectrometry. 4-Aminobiphenyl-DNA adducts were higher in smokers of air-cured tobacco and in current smokers, but no relationship with the number of cigarettes smoked was found. Adducts were higher in more advanced histologic grades of tumors. No pattern was evident for p53 mutations. Seven of 9 mutations occurred in grade 3 tumors. No association was found between 4-ABP adducts and GSTM1 or NAT2 genetic polymorphisms.

Anti-GM1, anti-central myelin proteins, and anti-cardiolipin autoantibodies during plasma-exchange in Guillain-Barré syndrome (GBS).

We measured the autoantibodies to GM1, central myelin proteins, and cardiolipin in 30 GBS patients using sensitive ELISA and Western blot techniques. The sequential modifications of titers during plasma-exchange (PE) and at follow-up were investigated in 15 patients. In pretreatment sera, we found significantly increased antibody titers to GM1 (37% of the patients), central myelin proteins (28%), and cardiolipin (21%). Seventeen patients out of 29 (58%) presented increased IgG or IgM antibody to at least one of the antigens considered as compared to 10 out of 70 controls (14%, P = 0.00001). By Western blot, IgG or IgM antibodies reactive with the triton insoluble fraction of central myelin were observed in 19 out of 28 GBS patients (67%). The follow-up measurements during and after PE showed a declining autoantibody titer in 10 out of 15 patients. However, in the remaining 5 GBS patients, we observed a persistently elevated titer or an increase from baseline values occurring during or after PE and reaching a peak. In 2 of the 5 patients, the titer peak preceded a clinical re-exacerbation. The presence of a persistently elevated or an increasing autoantibody titer during treatment with PE merits further investigation and may help to clarify the pathogenesis of GBS and improve its treatment.

GAS6, the ligand of Axl and Rse receptors, is expressed in hematopoietic tissue but lacks mitogenic activity.

GAS6, a gene previously identified as growth arrest specific, has been demonstrated to be the ligand of Axl, a novel tyrosine kinase receptor widely expressed in both normal and neoplastic hematopoietic tissue. We have observed previously that GAS6 mRNA was present in whole bone marrow. This preliminary finding prompted us to investigate the presence of GAS6 in hematopoietic tissue and the possible role of this molecule in controlling the proliferation of hematopoietic precursors. We report here that the protein GAS6 is diffusely present in hematopoietic tissue, both in stromal and in hematopoietic cells, and that, among these cells, positivity is observed in megakaryocytes and myelomonocytic precursors. Furthermore, our data suggest that GAS6 is not a growth factor for hematopoietic progenitors or stromal fibroblasts. Despite the fact that both the Axl receptor and its ligand, GAS6, are expressed in hematopoietic tissue, the biological role of their interactions remains to be determined.

An erythroid and megakaryocytic common precursor cell line (B1647) expressing both c-mpl and erythropoietin receptor (Epo-R) proliferates and modifies globin chain synthesis in response to megakaryocyte growth and development factor (MGDF) but not to erythropoietin (Epo).

A human megakaryocyte cell line (B1647) has been established from bone marrow cells obtained from a patient with acute myelogenous leukaemia (FAB M2). The cells were CD34-, CD33+, HLA-DR+, CD38+, and expressed the immunophenotypic markers of the megakaryocyte lineage (CD41 and von Willebrand factor). Moreover the cells expressed the c-mpl (thrombopoietin receptor) mRNA and protein. On the other hand, the B1647 cells also possessed erythroid lineage characteristics: the vast majority of cells were glycophorin positive, and about 10% of unstimulated cells stained with an anti-globin gamma chain MoAb. In addition, S1 protection analysis demonstrated expression of beta-globin mRNA, and Epo receptor (Epo-R) protein was detected by cytofluorimetric assay. Several growth factors, when tested alone or in combination, failed to influence the B1647 cell growth. A significant increase of cell proliferation was observed only after the addition, in serum-free culture, of recombinant human megakaryocyte growth development factor (MGDF), a recombinant c-mpl ligand encompassing the receptor-binding domain and identical to thrombopoietin (TPO), at concentrations ranging from 0.01 to 1 ng/ml. Interestingly, MGDF failed to induce megakaryocytic differentiation of the B1647 cells, but significantly increased the synthesis of the globin gamma-chain. B1647 cells could be a useful model for studying the biological effect of TPO on common megakaryocyte and erythroid progenitors.

Role of prolactin in the in vitro development of interleukin-2-driven anti-tumoural lymphokine-activated killer cells.

Exogenous prolactin (PRL) has been shown to synergize with low-dose interleukin-2 (IL-2) and induce the proliferation and lymphokine-activated killer (LAK) maturation of natural killer (NK) cells. PRL itself can also generate LAK activity. Here we show that its local production occurs during, and is necessary for, LAK development. IL-2-stimulated peripheral blood mononuclear cells (PBMC) and purified NK cells were exposed to anti-human (h)PRL antiserum, and residual LAK activity was measured on day 7 against the promyelocytic leukaemia cell line HL-60. Inhibition of LAK activity was much more evident in PBMC compared with NK cell cultures (47% decrease. P - 0.013 and 18.5% decrease. P = 0.048, respectively). Up-modulation of a 32S-methionine-labelled 27,000 MW protein was detected in the lysates and supernatants of IL-2-stimulated PBMC immunoprecipitated with an anti-PRL antiserum. By contrast, the cytoplasmic PRL immunoreactivity observed in freshly isolated NK cells and in IL-2-stimulated, but not unstimulated, NK cell cultures was not associated with PRL gene activation, and can thus be referred to internalized PRL. Preferential re-uptake of externally derived PRL by IL-2-stimulated NK cells was also indicated by up-modulation of the PRL receptor. These data, as a whole, indicate that the PRL promotion of LAK differentiation is mainly mediated by paracrine secretion, with a minor contribution from internalized PRL.