Optimized Flow Cytometry Strategy for Phenotyping Intramuscular Leukocytes: Application to the Evaluation of Myopathological Processes

Phenotyping intramuscular immune cells is essential for the characterization of dysimmune/inflammatory myopathies (DIM). Flow cytometry (FC) is the most reliable technique for analyzing leukocyte subpopulations and evaluating their activation levels. We developed a purely mechanical protocol for extracting cells from muscle tissue allowing us to preserve cell surface epitopes and determined its applicability to experimental pathology in mice and myopathological diagnosis in human. Skeletal muscle regeneration in mice was associated with a transient enrichment of macrophages (CD11bhighGr-1+), myeloid dendritic cells (CD3−C8+CD11bhigh), CD8+ T cells (CD3+C8+), and NK cells (CD3− CD11bhighNKp46+). In murine models of inherited muscle dystrophies, leukocytes represented 23%–84% of intramuscular mononuclear cells, with a percentage of CD8+ T cells (4%–17%) mirroring that of all CD45+ cells, while MDCs remained a minority. In human 16 samples (DIM: n = 9; nonimmune conditions: n = 7), DIM was associated with intramuscular recruitment of CD8+ T cells, but not CD4+ T cells and NK cells. FC allowed concomitant quantification of HLA-DR, CD25, CD38, and CD57 activation/differentiation biomarkers and showed increased activation levels of CD4+ and CD8+ T cells in DIM. In conclusion, FC is an appropriate method for quantifying intramuscular leukocyte subpopulations and analyzing their activation states.

Alveolar compartmentalization of inflammatory and immune cell biomarkers in pneumonia-related ARDS

Background

Biomarkers of disease severity might help individualizing the management of patients with the acute respiratory distress syndrome (ARDS). Whether the alveolar compartmentalization of biomarkers has a clinical significance in patients with pneumonia-related ARDS is unknown. This study aimed at assessing the interrelation of ARDS/sepsis biomarkers in the alveolar and blood compartments and explored their association with clinical outcomes.

Methods

Immunocompetent patients with pneumonia-related ARDS admitted between 2014 and 2018 were included in a prospective monocentric study. Bronchoalveolar lavage (BAL) fluid and blood samples were obtained within 48 h of admission. Twenty-two biomarkers were quantified in BAL fluid and serum. HLA-DR⁺ monocytes and CD8⁺ PD-1⁺ lymphocytes were quantified using flow cytometry. The primary clinical endpoint of the study was hospital mortality. Patients undergoing a bronchoscopy as part of routine care were included as controls.

Results

Seventy ARDS patients were included. Hospital mortality was 21.4%. The BAL fluid-to-serum ratio of IL-8 was 20 times higher in ARDS patients than in controls (p < 0.0001). ARDS patients with shock had lower BAL fluid-to-serum ratio of IL-1Ra (p = 0.026), IL-6 (p = 0.002), IP-10/CXCL10 (p = 0.024) and IL-10 (p = 0.023) than others. The BAL fluid-to-serum ratio of IL-1Ra was more elevated in hospital survivors than decedents (p = 0.006), even after adjusting for SOFA and driving pressure (p = 0.036). There was no significant association between alveolar or alveolar/blood monocytic HLA-DR or CD8⁺ lymphocytes PD-1 expression and hospital mortality.

Conclusions

IL-8 was the most compartmentalized cytokine and lower BAL fluid-to-serum concentration ratios of IL-1Ra were associated with hospital mortality in patients with pneumonia-associated ARDS.

Combined Plasma Elevation of CRP, Intestinal-Type Fatty Acid-Binding Protein (I-FABP), and sCD14 Identify Older Patients at High Risk for Health Care-Associated Infections

Background

We hypothesized that low-grade inflammation was driven by microbial translocation and associated with an increased risk of health care-associated infections (HAIs).

Methods

We included 121 patients aged 75 years or over in this prospective cohort study. High-sensitivity C-reactive protein (hs-CRP), I-FABP, and sCD14-as markers for low-grade inflammation, intestinal epithelial barrier integrity, and monocyte activation, respectively-were measured at admission.

Results

HAIs occurred during hospitalization in 62 (51%) patients. Elevated hs-CRP (≥6.02 mg/L, ie, the median) was associated with a significantly higher HAI risk when I-FABP was in the highest quartile (odds ratio [OR], 4; 95% confidence interval [95% CI], 1.39-11.49; p = .010). In patients with hs-CRP elevation and highest-quartile I-FABP, sCD14 elevation (≥0.65 µg/mL, ie, the median) was associated with an 11-fold higher HAI risk (OR, 10.8; 95% CI, 2.28-51.1; p = .003). Multivariate analyses adjusted for invasive procedures and comorbidities did not change the associations linking the three markers to the HAI risk.

Conclusion

Increased levels of hs-CRP, I-FABP, and sCD14 may reflect loss of intestinal epithelial barrier integrity with microbial translocation leading to monocyte activation and low-grade inflammation. In our cohort, these markers identified patients at high risk for HAIs.

[Leg ulcer associated with type I cryoglobulinaemia due to incipient B-cell lymphoma]

BACKGROUND

Skin lesions are frequent in monoclonal cryoglobulinaemia and may be the first sign of B-cell lymphoma, especially multiple myeloma, Waldenström's macroglobulinaemia and B-cell chronic lymphocytic leukaemia.

PATIENTS AND METHODS

A 74-year-old woman with no prior medical history presented with necrotic leg ulcer. Skin biopsy showed dermal angiomatosis with numerous PAS+ thromboses, associated with monoclonal intravascular deposits of IgM kappa, indicating monoclonal cryoglobulin, which was confirmed by laboratory tests. Subsequent blood immunophenotyping revealed an inconspicuous circulating monoclonal CD5(+) B-cell population and small B-cell clusters in the bone marrow, while the B-cell count was normal and no lymphadenopathy or splenomegaly were present. Overall, these findings indicated a small B-cell lymphoma, classed as non-MALT marginal zone lymphoma on the WHO classification, at a very early stage of development. The patient was first treated by cyclophosphamide and oral steroids without success. Subsequent administration of six cycles of rituximab, cyclophosphamide, vincristine and prednisone (RCVP) led to remission of her leg ulcer, cryoglobulinaemia and lymphoma.

CONCLUSION

Skin biopsies of necrotic ulcers should undergo routine screening for intravascular deposits of type 1 cryoglobulin. Leg ulcers due to monoclonal cryoglobulinaemia may reveal incipient marginal zone B-cell lymphoma at the stage of circulating monoclonal lymphocytosis.

Clinical relevance of flow cytometric immunophenotyping of the cerebrospinal fluid in patients with diffuse large B-cell lymphoma

BACKGROUND

Central nervous system (CNS) relapse is an uncommon but dramatic complication of diffuse large B-cell lymphoma (DLBCL). Several studies have demonstrated the superiority of cerebrospinal fluid (CSF) flow cytometry (FCM), as compared with conventional cytology (CC), in detecting occult leptomeningeal disease. The clinical relevance of a positive FCM still has to be clarified.

PATIENTS AND METHODS

We analyzed CSF from 114 DLBCL patients at diagnosis (n = 95) or at relapse (n = 19) by FCM and CC. Most patients received meningeal prophylaxis. FCM results did not influence treatment strategies.

RESULTS

Fourteen samples were FCM+, versus one CC+ (also FCM+). Within all patients without neurological symptoms (n = 101), four (4%) relapsed in the CNS, with a median time to relapse of 5.2 months. Only one-fourth (25%) was FCM+ before relapse. More than one extranodal disease site and elevated lactate dehydrogenase levels were associated with an increased risk of CNS relapse.

CONCLUSIONS

FCM gives far more positive results than CC. However, a positive FCM result did not translate into a significant increase in CNS relapse rate in this histologically uniform population receiving CNS prophylaxis.

Targeting intratumoral B cells with rituximab in addition to CHOP in angioimmunoblastic T-cell lymphoma. A clinicobiological study of the GELA

BACKGROUND

In angioimmunoblastic T-cell lymphoma, symptoms linked to B-lymphocyte activation are common, and variable numbers of CD20(+) large B-blasts, often infected by Epstein-Barr virus, are found in tumor tissues. We postulated that the disruption of putative B-T interactions and/or depletion of the Epstein-Barr virus reservoir by an anti-CD20 monoclonal antibody (rituximab) could improve the clinical outcome produced by conventional chemotherapy.

DESIGN AND METHODS

Twenty-five newly diagnosed patients were treated, in a phase II study, with eight cycles of rituximab + chemotherapy (R-CHOP21). Tumor infiltration, B-blasts and Epstein-Barr virus status in tumor tissue and peripheral blood were fully characterized at diagnosis and were correlated with clinical outcome.

RESULTS

A complete response rate of 44% (95% CI, 24% to 65%) was observed. With a median follow-up of 24 months, the 2-year progression-free survival rate was 42% (95% CI, 22% to 61%) and overall survival rate was 62% (95% CI, 40% to 78%). The presence of Epstein-Barr virus DNA in peripheral blood mononuclear cells (14/21 patients) correlated with Epstein-Barr virus score in lymph nodes (P<0.004) and the detection of circulating tumor cells (P=0.0019). Despite peripheral Epstein-Barr virus clearance after treatment, the viral load at diagnosis (>100 copy/μg DNA) was associated with shorter progression-free survival (P=0.06).

CONCLUSIONS

We report here the results of the first clinical trial targeting both the neoplastic T cells and the microenvironment-associated CD20(+) B lymphocytes in angioimmunoblastic T-cell lymphoma, showing no clear benefit of adding rituximab to conventional chemotherapy. A strong relationship, not previously described, between circulating Epstein-Barr virus and circulating tumor cells is highlighted.

Immune risk phenotype is associated with nosocomial lung infections in elderly in-patients

BACKGROUND

Nosocomial infections are extremely common in the elderly and may be related to ageing of the immune system. The Immune Risk Phenotype (IRP), which predicts shorter survival in elderly patients, has not been evaluated as a possible risk factor for nosocomial infection. Our aim was to assess the prevalence of nosocomial infections in elderly in-patients and to investigate potential relationships between nosocomial infections and the immunophenotype, including IRP parameters.

RESULTS

We included 252 consecutive in-patients aged 70 years or over (mean age, 85 ± 6.2 years), between 2006 and 2008. Among them, 97 experienced nosocomial infections, yielding a prevalence rate of 38.5% (95% confidence interval, 32.5-44.5). The main infection sites were the respiratory tract (21%) and urinary tract (17.1%) When we compared immunological parameters including cell counts determined by flow cytometry in the groups with and without nosocomial infections, we found that the group with nosocomial infections had significantly lower values for the CD4/CD8 ratio and naive CD8 and CD4 T-cell counts and higher counts of memory CD8 T-cells with a significant increase in CD28-negative CD8-T cells. Neither cytomegalovirus status (positive in 193/246 patients) nor presence of the IRP was associated with nosocomial infections. However, nosocomial pneumonia was significantly more common among IRP-positive patients than IRP-negative patients (17/60 versus 28/180; p = 0.036).

CONCLUSION

Immunological parameters that are easy to determine in everyday practice and known to be associated with immune system ageing and shorter survival in the elderly are also associated with an elevated risk of nosocomial pneumonia in the relatively short term.

T-cell phenotype in protocol renal biopsy from transplant recipients treated with belatacept-mediated co-stimulatory blockade

BACKGROUND

Belatacept is thought to disrupt the interaction between CD80/86 and CD28, thus preventing T-cell activation by blocking the co-stimulatory second signal. However, the consequences on the T-cell profile in human renal transplant cases have not been determined.

METHODS

In this study, we analysed intra-graft levels of the mRNAs for Treg (FOXP3), cytotoxic CD8 T cells (Granzyme B), Th1 (INFγ, Tbet), Th2 (GATA3) and Th17 (RORγt and IL-17) in protocol biopsies obtained 12 months after renal transplantation in recipients treated with Belatacept or calcineurin inhibitor (CNI).

RESULTS

Only the intra-graft abundance of FOXP3 mRNA was significantly lower (P < 0.001) in the Belatacept group than the CNI group. Conclusions. These results are in agreement with in vitro data suggesting that CD28 is a major co-stimulatory signal of both Tregs development and peripheral homeostasis but contrast with clinical trials showing a better 1-year graft function and a lower incidence of chronic allograft nephropathy in patients receiving Belatacept than patients treated with CNI. They suggest that immune benefits induced by Belatacept are not mediated by Treg expansion and that FOXP3 is not by itself a prognostic marker of long-term graft function in a non-inflammatory context. These results have to be, however, considered as preliminary since the size of our study population is limited.

The inducible T-cell co-stimulator molecule is expressed on subsets of T cells and is a new marker of lymphomas of T follicular helper cell-derivation

BACKGROUND

T follicular helper (T(FH)) cells reside in the light zone of germinal centers and are considered the cell of origin of angioimmunoblastic T-cell lymphoma. Recently, CXCL13, PD-1 and SAP were described as useful markers for T(FH) cells and angioimmunoblastic T-cell lymphoma but also reported in some peripheral T-cell lymphomas, not otherwise specified.

DESIGN AND METHODS

In the present study the expression pattern of ICOS protein was investigated by immunohistochemistry-based techniques in routine sections of normal lymphoid tissues and 633 human lymphomas.

RESULTS

Cells strongly positive for ICOS were restricted to the light zone of germinal centers and co-expressed T(FH)-associated molecules. In addition, weak to moderate ICOS expression was observed in a small proportion of FOXP3-positive cells. In lymphomas, ICOS expression was confined to angioimmunoblastic T-cell lymphoma (85/86), peripheral T-cell lymphomas of follicular variant (18/18) and a proportion of peripheral T-cell lymphomas, not otherwise specified (24/56) that also expressed other T(FH)-associated molecules.

CONCLUSIONS

ICOS is a useful molecule for identifying T(FH) cells and its restricted expression to angioimmunoblastic T-cell lymphoma and a proportion of peripheral T-cell lymphomas, not otherwise specified (showing a T(FH)-like profile) suggests its inclusion in the antibody panel for diagnosing T(FH)-derived lymphomas. Our findings provide further evidence that the histological spectrum of T(FH)-derived lymphomas is broader than previously assumed.

Muscle resident macrophages control the immune cell reaction in a mouse model of notexin-induced myoinjury

OBJECTIVE

Skeletal muscle may be the site of a variety of poorly understood immune reactions, particularly after myofiber injury, which is typically observed in inflammatory myopathies. This study was undertaken to explore both the cell dynamics and functions of resident macrophages and dendritic cells (DCs) in damaged muscle, using a mouse model of notexin-induced myoinjury to study innate immune cell reactions.

METHODS

The myeloid cell reaction to notexin-induced myoinjury was analyzed by microscopy and flow cytometry. Bone marrow (BM) transplantation studies were used to discriminate resident from exudate monocyte/macrophages. Functional tests included cytokine screening and an alloantigenic mixed leukocyte reaction to assess the antigen-presenting cell (APC) function. Selective resident macrophage depletion was obtained by injection of diphtheria toxin (DT) into CD11b-DT receptor-transgenic mice transplanted with DT-insensitive BM.

RESULTS

The connective tissue surrounding mouse muscle/fascicle tissue (the epimysium/perimysium) after deep muscle injury displayed a resident macrophage population of CD11b+F4/80+CD11c-Ly-6C-CX3CR1- cells, which concentrated first in the epimysium. These resident macrophages were being used by leukocytes as a centripetal migration pathway, and were found to selectively release 2 chemokines, cytokine-induced neutrophil chemoattractant and monocyte chemoattractant protein 1, and to crucially contribute to massive recruitment of neutrophils and monocytes from the blood. Early epimysial inflammation consisted of a predominance of Ly-6C(high)CX3CR1(low)CD11c- cells that were progressively substituted by Ly-6C(low)CX3CR1(high) cells displaying an intermediate, rather than high, level of CD11c expression. These CD11c(intermediate) cells were derived from circulating CCR2+ monocytes, functionally behaved as immature APCs in the absence of alloantigenic challenge, and migrated to draining lymph nodes while acquiring the phenotype of mature DCs (CD11c+Ia+CD80+ cells, corresponding to an inflammatory DC phenotype).

CONCLUSION

The results in this mouse model show that resident macrophages in the muscle epimysium/perimysium orchestrate the innate immune response to myoinjury, which is linked to adaptive immunity through the formation of inflammatory DCs.

Flow cytometric immunophenotyping of cerebrospinal fluid

Leptomeningeal disease is an important adverse complication occurring in patients with B and T cell lymphomas and acute leukemias of lymphoid and myeloid origin. Recent reports suggest that multiparameter flow cytometry immunophenotypic assessment of spinal fluid samples could improve the efficiency of detection of CNS involvement, due to its high specificity and greater sensitivity. However, spinal fluid samples are frequently paucicellular with a rapidly decreasing cell viability. Staining of spinal fluid therefore requires dedicated sample storage/transport, staining, and preparation protocols. The Basic Protocol in this unit outlines a consensus multiparameter (3- to 8-color) flow cytometry immunophenotypic protocol for the evaluation of CNS involvement of cerebrospinal fluid (CSF) samples by neoplastic cells. A Support Protocol describing the simultaneous assessment of surface and cytoplasmic antigens is also provided. Finally, in the Alternate Protocol, we describe a method to calculate absolute numbers of both normal and pathological cell subpopulations by adding counting beads to the assay.

Characterization of CXCL13+ Neoplastic T Cells in Cutaneous Lesions of Angioimmunoblastic T-cell Lymphoma (AITL)

Skin manifestations of angioimmunoblastic T-cell lymphoma (AITL) are frequent, sometimes as first manifestations of the disease. In the absence of a specific marker for neoplastic cells, diagnosis of AITL in skin biopsies is often difficult. CD10 and CXCL13 have been recently recognized as characteristic markers of AITL, but have not been yet investigated in the skin. We analyzed 15 skin biopsies from 8 patients with AITL having skin manifestations and compared them to 14 skin biopsies from patients with various cutaneous lymphocytic infiltrates. A few CD10 lymphocytes were found in only 2 samples of the AITL group, the identification of which was hampered by the presence of a dermal CD10 cell population with dendritic features. By contrast, CXCL13 lymphoid cells were identified in most AITL cutaneous biopsies (n=12, 80%), whereas, absent in all samples from control cases. Among 12 biopsies with CXCL13 cells, cutaneous involvement by AITL was suspected in only 5 on the basis of light microscopy and classic immunophenotyping. In another case, a diagnosis of cutaneous marginal zone B-cell lymphoma had been proposed. In conclusion, this study shows that neoplastic AITL CXCL13 T cells localize in the skin and that accurate diagnosis of AITL lesions can be done in skin specimens using CXCL13 immunostaining on paraffin-embedded tissues.

Peripheral blood natural killer cell count is associated with clinical outcome in patients with aaIPI 2-3 diffuse large B-cell lymphoma

BACKGROUND

Lymphocytopenia is a prognostic factor in Hodgkin's disease. In diffuse large B-cell lymphoma (DLBCL), data are much less established, in spite of numerous reports on immune system-lymphoma interactions. This study addresses the prognostic value of blood lymphocyte subsets at diagnosis in DLBCL.

PATIENTS AND METHODS

Absolute values of blood lymphocyte subsets and monocytes were prospectively determined by flow cytometry in 140 patients with 2 or 3 adverse age-adjusted International Prognostic Index (aaIPI) factors included in a Groupe d'Etude des Lymphomes de l'Adulte protocol (LNH98B3). Absolute cell counts at diagnosis and aaIPI were evaluated with regard to clinical outcome.

RESULTS

Low median cell counts of 337, 211, and 104/mul were evidenced for the CD4+, CD8+ T, and natural killer (NK) cells, respectively. In univariate analysis, only NK cell count [odds ratio (OR) = 1.81 (1.27, 2.57), P = 0.001] and aaIPI [OR = 2.29 (0.95, 5.45), P = 0.06] were associated with induction treatment response. Low NK cell count [Hazard ratio (HR) = 1.27 (1.06, 1.52), P = 0.01] and aaIPI 3 [HR = 1.95 (1.20, 3.16), P = 0.01] were also associated with a shorter event free survival (EFS). In multivariate analysis, NK cell count was associated with response [OR = 1.77 (1.24, 2.54), P = 0.002] and EFS [HR = 1.25 (1.04, 1.50) P = 0.02] independently of aaIPI.

CONCLUSIONS

This study shows an association between circulating NK cell number and clinical outcome in DLBCL, possibly important in the context of the broadening use of rituximab, a likely NK-dependent therapy.

Inflammatory monocytes recruited after skeletal muscle injury switch into antiinflammatory macrophages to support myogenesis

Macrophages (MPs) are important for skeletal muscle regeneration in vivo and may exert beneficial effects on myogenic cell growth through mitogenic and antiapoptotic activities in vitro. However, MPs are highly versatile and may exert various, and even opposite, functions depending on their activation state. We studied monocyte (MO)/MP phenotypes and functions during skeletal muscle repair. Selective labeling of circulating MOs by latex beads in CX3CR1(GFP/+) mice showed that injured muscle recruited only CX3CR1(lo)/Ly-6C(+) MOs from blood that exhibited a nondividing, F4/80(lo), proinflammatory profile. Then, within muscle, these cells switched their phenotype to become proliferating antiinflammatory CX3CR1(hi)/Ly-6C(-) cells that further differentiated into F4/80(hi) MPs. In vitro, phagocytosis of muscle cell debris induced a switch of proinflammatory MPs toward an antiinflammatory phenotype releasing transforming growth factor beta1. In co-cultures, inflammatory MPs stimulated myogenic cell proliferation, whereas antiinflammatory MPs exhibited differentiating activity, assessed by both myogenin expression and fusion into myotubes. Finally, depletion of circulating MOs in CD11b-diphtheria toxin receptor mice at the time of injury totally prevented muscle regeneration, whereas depletion of intramuscular F4/80(hi) MPs at later stages reduced the diameter of regenerating fibers. In conclusion, injured skeletal muscle recruits MOs exhibiting inflammatory profiles that operate phagocytosis and rapidly convert to antiinflammatory MPs that stimulate myogenesis and fiber growth.

Expression of CXCL13 by Neoplastic Cells in Angioimmunoblastic T-Cell Lymphoma (AITL)

Angioimmunoblastic T-cell lymphoma (AITL) represents a distinct entity among peripheral T-cell lymphomas (PTCLs). The cellular origin of AITL remains unknown, although a possible derivation from follicular helper T cells (TFH) has been suggested based on the CD4/Bcl-6 phenotype. It has been recently shown that expression of CXCL13, a chemokine critically involved in B-cell migration into germinal centers, is characteristic of TFH cells, as compared with other T helper subsets. We compared CXCL13 expression in 29 AITLs, 20 PTCLs, unspecified, 10 anaplastic large cell lymphomas (ALCL), and 4 other PTCLs. We showed that CXCL13 is expressed by AITL (29 of 29, 100%) and a subset of PTCL, unspecified (6 of 20, 30%), which all showed borderline features with AITL, but in only 1 of 10 (10%) ALCLs, and 0 of 4 other PTCLs. Two-color immunostainings further showed that CXCL13 was found in the cytoplasm of atypical CD5-positive T cells that expressed CD10. We conclude that CXCL13 expression is a common characteristic of AITL, which can help to delineate the morphologic spectrum of the disease, and further supports its derivation from TFH cells. CXCL13 expression may also provide an additional useful tool for the diagnosis of AITL.

BLOOD NEUTROPHIL BACTERICIDAL ACTIVITY AGAINST METHICILLIN-RESISTANT AND METHICILLIN-SENSITIVE STAPHYLOCOCCUS AUREUS DURING CARDIAC SURGERY

Whether methicillin-resistant Staphylococcus aureus (MRSA) constitutes per se an independent risk factor for morbidity and mortality after surgery as compared with methicillin-sensitive Staphylococcus aureus (MSSA) remains a subject of debate. The aim of this study was to assess whether innate defenses against MRSA and MSSA strains are similarly impaired after cardiac surgery. Both intracellular (isolated neutrophil functions) and extracellular (plasma) defenses of 12 patients undergoing scheduled cardiac surgery were evaluated preoperatively (day 0) and postoperatively (day 3) against two MSSA strains with a low level of catalase secretion and two MRSA strains with a high level of catalase secretion, inasmuch as SA killing by neutrophils relies on oxygen-dependent mechanisms. After surgery, an increase in plasma concentration of IL-10, an anti-inflammatory cytokine able to inhibit reactive oxygen species secretion and bactericidal activity of neutrophils, was evidenced. Despite the fact that univariate analysis suggested a specific impairment of neutrophil functions against MRSA strains, two-way repeated-measures ANOVA failed to demonstrate that the effect of S. aureus phenotype was significant. On the other hand, an increase in type-II secretory phospholipase A2 activity, a circulating enzyme involved in SA lysis, was evidenced and was associated with an enhancement of extracellular defenses (bactericidal activity of plasma) against MRSA. Overall, cardiac surgery and S. aureus phenotype had a significant effect on plasma bactericidal activity. Cardiac surgery was characterized by enhanced antibacterial defenses of plasma, whereas neutrophil killing properties were reduced. The overall effect of S. aureus phenotype on neutrophil functions did not seem significant.

Peptides derived from the onconeural HuD protein can elicit cytotoxic responses in HHD mouse and human

Anti-Hu syndrome is a paraneoplastic neurologic disease seemingly associated with an efficient antitumoral immune response against HuD protein expressed by both small cell lung cancer (SCLC) and neurons. Since anti-Hu antibodies are not pathogenic, and oligoclonal CD8(+) T cells infiltrate neoplastic and nervous tissues, we examined MHC class I-restricted immunogenicity of human HuD. Among 14 HuD-derived peptides potentially immunogenic in HLA-A*0201 restriction, 10 had actual in vitro binding capacity to the HLA molecule, 8 elicited specific cytotoxic T lymphocytes (CTLs) in a humanized murine model after peptidic vaccination, 2 also elicited specific CTLs in healthy humans, and 1 was naturally processed and presented to the immune system.

Toxoplasmic myositis as a presenting manifestation of idiopathic CD4 lymphocytopenia

Toxoplasma gondii encysts in skeletal muscle. Although only rarely found at muscle biopsy, this parasite has previously been regarded as a possible cause of polymyositis. We report a case of biopsy-proven toxoplasmic myositis in a non-HIV-infected patient that led to recognition of idiopathic CD4 lymphocytopenia (ICL), a rare condition typically associated with opportunistic infections. Interestingly, the CD25(+) subset that corresponds to the CD4(+) regulatory T cells controlling autoimmune processes was lacking. Steroid and antiprotozoal therapy led to recovery.

Inflammatory myopathy with abundant macrophages (IMAM): a condition sharing similarities with cytophagic histiocytic panniculitis and distinct from macrophagic myofasciitis

We describe the unreported pattern of inflammatory myopathy with abundant macrophages (IMAM) as a main differential diagnosis of postimmunization aluminum hydroxide-induced macrophagic myofasciitis (MMF). IMAM was mainly detected among patients with a dermatomyositis (DM)-like disease. Among 113 muscle biopsies from DM patients collected from 1974 to 2000, intensity of macrophage infiltration was highly variable: 41.5% (-/+); 34.5% (+); 17% (++): and 7% (+++). The 27 patients from groups (++) and (+++) had a similar pattern of macrophagic infiltration and were considered to have IMAM. They were compared to 40 MMF patients. In IMAM, macrophage infiltrates were diffuse and correlated positively with both T cell infiltrates and acute muscle fiber damage, and showed pictures of hemophagocytosis (21/27). Connective tissue structures were infiltrated by noncohesive, ribbon-forming collections of large basophilic macrophages containing no crystalline inclusions. In MMF, macrophage infiltrates were focal and formed compact well-delineated aggregates of granular PAS+ cells, loaded with crystalline aluminum hydroxide particles, in the absence of either hemophagocytosis or conspicuous muscle damage. Review of the literature indicates similarities between IMAM and "cytophagic histiocytic panniculitis" (CHP), a condition characterized by T cell-triggered macrophage hyperactivation. Both IMAM and CHP, but not MMF, may be associated with a life-threatening hemophagocytic syndrome.

Monocyte chemoattractant protein 1 and chemokine receptor CCR2 productions in Guillain-Barré syndrome and experimental autoimmune neuritis

Infiltration of activated lymphocytes and monocytes is a key phenomenon in the pathogenesis of Guillain-Barré syndrome (GBS) and experimental autoimmune neuritis (EAN). To investigate the role of chemokines, we determined the blood and nerve tissue expression of monocyte chemoattractant protein 1 (MCP-1), a major chemoattractant of monocytes and activated lymphocytes, and its receptor CCR2 in GBS and EAN. MCP-1 circulating levels (ng/ml) in GBS were increased at the time of progression, peaked at the time of plateau and normalized with recovery. MCP-1 circulating levels were the highest in the most disabled patients. The number of circulating CCR2 positive cells was lower in patients with GBS than in healthy subjects (p<0.004). In GBS, MCP-1 expression was observed in epineurial and endoneurial vessels, on infiltrating cells, Schwann cells and in the endoneurial extracellular matrix. Some CCR2 positive cells were observed in nerve biopsies of GBS patients. In EAN, a slight positivity for MCP-1 was observed in the sciatic nerve. There was no circulating CCR2 positive cells. However, at the time of plateau, a conspicuous infiltration of CCR2 positive cells was observed in the sciatic nerve that was no longer observed at the time of recovery. These results suggest that MCP-1 and CCR2 may participate to the recruitment of circulating mononuclear cells in nerve tissue in EAN and GBS.

MAL expression in lymphoid cells: further evidence for MAL as a distinct molecular marker of primary mediastinal large B-cell lymphomas

The MAL mRNA was initially identified during T-cell development and was later found in myelin-forming cells and certain polarized epithelial cell lines. It encodes a proteolipid believed to participate in membrane microdomains stabilization, transport machinery and signal transduction. Using a differential display reverse-transcription approach, we identified MAL as a distinct molecular marker of primary mediastinal large B-cell lymphoma compared with nonmediastinal diffuse large B-cell lymphomas. In the present study, we used immunohistochemistry to extend MAL expression analysis to normal lymphoid tissues; to 185 lymphomas representing most B, T, and Hodgkin lymphoma entities; and to the primary mediastinal large B-cell lymphoma derived B-cell line MedB-1. In addition, B and T cells from peripheral blood, tonsil, and spleen were analyzed by flow cytometry. Our results show that MAL is highly expressed in thymocytes, in a large percentage of peripheral CD4 T cells, and in a lower proportion of CD8 peripheral T cells. In the normal B-cell compartment, MAL expression appears to be restricted to a minor subpopulation of thymic medullary B cells and to occasional mature plasma cells located in the interfollicular areas of tonsil and lymph nodes. Among B-cell lymphomas (n = 110), MAL expression in tumor cells was observed in 21/33 primary mediastinal large B-cell lymphomas (70%) and in 3/5 plasmacytoma/myeloma, but not in all other B-cell lymphomas with the exception of 1/33 nonmediastinal diffuse large B-cell lymphomas. The MedB-1 B-cell line was also MAL positive. Among T-cell neoplasms, MAL was highly expressed in lymphoblastic tumors (5/6), whereas mature T-cell lymphomas were essentially MAL negative (27/28). Among 41 Hodgkin lymphomas, 3 nodular-sclerosing cases with mediastinal involvement showed MAL-positive Reed Sternberg cells. In conclusion, this study further supports thymic B cells as the putative normal counterpart of primary mediastinal large B-cell lymphomas and supports MAL as a distinct molecular marker of this lymphoma subtype among diffuse large B-cell lymphomas.

IL-12 secreting dendritic cells are required for optimum activation of human secondary lymphoid tissue T cells

Successful immunization requires that mature dendritic cells (mDCs) prime T cells in secondary lymphoid tissue (LT). Previously, the authors have shown that LT T cell activation has an increased costimulatory threshold for a proliferative response as compared with peripheral blood (PB) T cells. Therefore, to optimize mDC immunogenicity, DC maturation was studied using LT T cells as responders. While mDCs obtained with soluble CD40Ligand (sCD40L) or a sCD40L/IFNgamma combination similarly expressed the CD83 and CCR7 molecules on their membrane, only the latter secreted IL-12. sCD40L/IFNgamma mDCs, as compared with sCD40L mDCs, enhanced allogeneic LT T cell proliferation, LT CD4+ cell IFNgamma production and LT CD8+ cell cytotoxicity. Enhancement could be predominantly ascribed to IL-12 secreted by sCD40L/IFNgamma mDCs and to additional costimulatory signals as shown remarkably in the IFNgamma response when IL-12 was neutralized. Therefore, in addition to their membrane phenotype, mDCs to be used in immunization protocols should be assessed for IL-12 secretion as a surrogate marker for an optimum costimulatory potential.

Oligoclonal T-cells in blood and target tissues of patients with anti-Hu syndrome

T-cell clones of unknown significance (TCUS), assessed by monoclonal or oligoclonal T-cell patterns in PCR-DGGE, were detected in blood of 7/9 patients with anti-Hu syndrome. Clonal patterns were also detected in 2/2 neoplastic lymph nodes, and in 2/2 inflamed dorsal root ganglia from three patients. Only some T-cell clones found in target tissues were also detected in blood or non-target tissues, and likely corresponded to TCUS. In one patient, an identical T-cell clone was found in both neoplastic lymph node tissue and dorsal root ganglia, but not in blood. Dorsal root-infiltrating lymphocytes were cytotoxic CD8(+) TIA-1(+) T-cells. They were often found in close contact to sensory neurons, most of which expressed MHC-1. Taken together, these data support a direct effector role of cytotoxic CD8(+) T-cells, the same clones being likely operative in sensory neuron damage and immune-mediated tumor growth control.

Promigratory effect of plasminogen activator inhibitor-1 on invasive breast cancer cell populations

The urokinase-type plasminogen activator (uPA) system is a dynamic complex in which the membrane receptor uPAR binds uPA that binds the plasminogen activator inhibitor (PAI)-1 localized in the extracellular matrix, resulting in endocytosis of the whole complex by the low-density lipoprotein receptor-related protein (LRP). High expression of PAI-1 is paradoxically associated with marked tumor spreading and poor prognosis. We previously reported a nonproteolytic role of the [uPAR:uPA:PAI-1:LRP] complex operative in cell migration. Here we explored whether matrix PAI-1 could be used as a migration support by human breast cancer cells. We showed that the uPA system and LRP are localized at filopodia of invasive cells, and that formation/internalization of the [uPAR:uPA:PAI-1:LRP] complex is required for attachment and migration of cancer cells on plastic and on a PAI-1 coat. PAI-1 increased both filopodia formation and migration of cancer cells suggesting a chemokine-like activity. Migration velocity, expression of the uPA system, use of the [uPAR:uPA:PAI-1:LRP] complex to migrate, and promigratory effects of PAI-1 paralleled cancer cell invasiveness. Phenotyping and functional analysis of invasive cancer cell subclones indicated that different cell subpopulations may use different strategies to migrate depending on both the environment and their expression of the uPA system, some of them taking advantage of abundant available PAI-1.

IFN-beta decreases adhesion and transmigration capacities of lymphocytes in Guillain-Barré syndrome

The adhesion capacities, transmigration capacities, and integrin expression of lymphocytes from patients with Guillain-Barré syndrome incubated with interferon-beta were studied. Interferon-beta induced a dose-dependent inhibition of lymphocyte adhesion to recombinant vascular adhesion molecule-1 (p < 0.0001) and recombinant intercellular adhesion molecule-1 (rICAM-1) (p < 0.01) without modulation of very late activation molecule-4 and lymphocyte function-associated antigen-1 expressions and a dose-dependent decrease of lymphocyte transmigration across fibronectin (p < 0.0001). Inhibition of adhesion to rICAM-1 was similar after long (18 hours) or short (5 minutes) incubation time. These results support the potential therapeutic benefit of interferon-beta in Guillain-Barré syndrome.

Inhibition of the adhesion step of leukodiapedesis: a critical event in the recovery of Guillain-Barré syndrome associated with accumulation of proteolytically active lymphocytes in blood

Intraneural inflammation, that reflects emigration of immune cells from blood to nerve tissue, is a critical event in Guillain-Barré syndrome pathogenesis. To investigate the adhesion and transmigration phases of leukodiapedesis, we determined in a series of patients with GBS: (1) circulating levels of soluble forms of adhesion molecules (sICAM-1 and sVCAM-1); (2) attachment capacities of circulating lymphocytes to rICAM-1 and rVCAM-1; (3) fibronectin-penetrating capacities of circulating lymphocytes; and (4) lymphocyte intracellular concentrations of MMP-9 at the different phases of GBS and in healthy controls. Circulating levels of sVCAM-1 and sICAM-1 were above normal values at the time of progression, markedly increased at the time of plateau (sVCAM-1: P<0.03; sICAM-1: P<0.02), and tended to normalize during recovery. The percentage of cells with attachment capacities to rVCAM-1 and to rICAM-1 decreased from progression to recovery by 30 and 31%, respectively (P<0.02). The number of circulating lymphocytes with fibronectin penetrating capacities was lower than controls at the time of progression (P<0.01), then progressively increased to reach values higher than controls at the time of late recovery (P<0.02). Cellular concentrations of MMP-9 in circulating lymphocytes paralleled their fibronectin penetrating capacities. These results suggest early emigration of lymphocytes into nerve, followed by shedding of adhesion molecules from endothelium, and late decrease of lymphocyte adhesion capacities. Plateau and recovery are associated with accumulation in the vascular compartment of still proteolytically active lymphocytes that can no longer adhere to endothelial cells. Modulation of the adhesion step of leukodiapedesis may be crucially involved in the switch from progression to plateau of GBS.

Involvement of the [uPAR:uPA:PAI-1:LRP] complex in human myogenic cell motility

The urokinase-type plasminogen activator system is a proteolytic system involved in tissue remodeling and cell migration. At the cell surface, receptor (uPAR)-bound urokinase (uPA) binds its inhibitor PAI-1, localized in the matrix, and the complex is internalized by endocytic receptors, such as the low-density lipoprotein receptor-related protein (LRP). We previously proposed a nonproteolytic role for the uPA system in human myogenic cell differentiation in vitro, i.e., cell fusion, and showed that myogenic cells can use PAI-1 as an adhesion matrix molecule. The aim of this study was to define the role of the uPA system in myogenic cell migration that is necessary for fusion. Using a two-dimensional motility assay and microcinematography, we showed that any interference with the [uPAR:uPA:PAI-1] complex formation, and interference with LRP binding to this complex, markedly decreased myogenic cell motility. This phenomenon was reversible and independent of plasmin activity. Inhibition of cell motility was associated with suppression of both filopodia and membrane ruffling activity. [uPAR:uPA:PAI-1:LRP] complex formation involves high-affinity molecular interactions and results in quick internalization of the complex. It is likely that this complex supports the membrane ruffling activity involved in the guidance of the migrating cell toward appropriate sites for attachment.

Adenoviral transduction of human 'clinical grade' immature dendritic cells enhances costimulatory molecule expression and T-cell stimulatory capacity

The therapeutic use of dendritic cells (DC) in antigen-specific anti-tumor vaccines, requires sufficient numbers of functional DC, the preparation of which should comply with the code of Good Manufacturing Practice. In addition, the expression of tumor specific antigen should be possible in these DC. As a preclinical step, the method reported here was developed in healthy volunteers. Monocytes (Mo) were isolated by leukapheresis from 12 donors, purified by elutriation and then cultured for 6 days in sealed bags in AIM-V serum free medium with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-13 (IL-13). Between 6x10(8) and 1x10(9) immature DC (iDC) could be differentiated from one leukapheresis. Cells displayed a characteristic iDC phenotype (CD1a(+), CD14(-), CD80(+), CD86(+), HLA DR(+), CD83(-)), and had potent allogeneic and antigen dependent autologous T cell-stimulatory capacity. Moreover, iDC could be further differentiated into mature DC by CD40 ligation as assessed by CD83 expression and the upregulation of HLA-DR and costimulatory molecules. After infection with a recombinant adenovirus encoding for beta-galactosidase (betaGal), 50% to 80% of iDC expressed betaGal without toxicity. Adenovirus infection increased the expression of both costimulatory molecules and CD83, and also increased allogeneic stimulatory capacity. Thus, the method developed here allows us to use large numbers of functional iDC as will be required for therapeutic uses in man. These DC can express a transgenic protein.

Differential expression of the IL-1 system components during in vitro myogenesis: implication of IL-1beta in induction of myogenic cell apoptosis

We evaluated the expression of IL-1 system by normal human myogenic cells during in vitro myogenesis and the effect of exogenous IL-1beta. Expression of IL-1alpha and beta, IL-1 receptor antagonist (IL-1Ra), IL-1RI and II, IL-1R accessory protein (IL-1RAcP) and IL-1beta converting enzyme (ICE) was studied by immunocytochemistry, immunoblotting, ELISA and RT - PCR. Cell proliferation was evaluated by [3H]thymidine incorporation, cell fusion by flow cytometry and cell death by in situ end-labelling. Human normal myogenic cells constitutively produced IL-1beta and ICE, with a maximum expression at time of cell fusion. IL-1Rs and IL-1RAcP expression reached a peak at time of commitment to fusion. Myogenic cells produced small amounts of IL-1Ra at latest stages of culture, and only the intracellular isoform. Exposure of cultures to exogenous IL-1beta (1-5 ng/ml) induced myogenic cell apoptosis, without effect on cell proliferation or fusion. IL-1beta-induced cell death was associated with morphological changes including spreading appearance of cells and alteration of cell alignment. We conclude that (1) human myogenic cells constitutively produce IL-1beta; (2) IL-1 system components are differentially expressed during in vitro myogenesis; (3) IL-1 system participates to the coordinated regulation of cell density during normal myogenesis, which could serve to control the muscle mass in vivo.

CD36 deficiency is frequent and can cause platelet immunization in Africans

BACKGROUND

CD36 is expressed on several cell lineages. About 5 to 10 percent of Asians lack platelet membrane CD36 (pCD36), but the frequency of pCD36 deficiency in other ethnic groups is not known. Persons who are pCD36-negative are apparently healthy but can develop CD36 isoimmunization.

STUDY DESIGN AND METHODS

The pCD36 phenotype was studied in 1885 subjects belonging either to a group of 1127 healthy French blood donors (almost all of whom were white Europeans) or to a group of 758 patients of known ethnic origin.

RESULTS

No pCD36-negative persons were found among the blood donors. Only 1 of the 301 white European patients was pCD36-negative. In contrast, 16 of the 206 sub-Saharan Africans was pCD36-negative, a proportion higher than that among that black Caribbeans (1/148, p<0.01). The frequency of pCD36-negative patients was similar in blacks with and without sickle cell disease. Monocyte CD36 (mCD36) expression was studied in 15 of 22 pCD36-negative individuals: it was <10 percent in 7 subjects (type I deficiency) and between 12 and 100 percent in 8 others (type II deficiency). Thirteen pCD36-negative individuals had risk factors for immunization, and 4 had anti-CD36. Some had a history resembling posttransfusion purpura (n = 2), platelet transfusion refractoriness (n = 1), and recurrent miscarriage (n = 1). No correlation was found between immunization and the amount of mCD36. Anti-CD36 from an immunized type II-deficient woman reacted with monocytes from normal controls but not with monocytes from type I- or type II-deficient individuals, and thus it is postulated that mCD36 could be structurally different in normal and type II CD36-deficient individuals.

CONCLUSION

CD36 deficiency is frequent in sub-Saharan Africans; development of anti-CD36 can lead to serious complications in multiply transfused patients, such as those with sicke cell disease.