Altered expressions of CXCR4 and CD26 on T-helper lymphocytes in hereditary hemorrhagic telangiectasia

Background

Hereditary hemorrhagic telangiectasia (HHT) is a rare genetic disease characterized by a deregulated neo-angiogenesis. Besides a mainly vascular phenotype (muco-cutaneous telangiectases, arteriovenous malformations), a specific risk of infection is suggested by case series of severe and atypical infections as well as by reports of decreased T and natural killer (NK) lymphocyte counts. As some evidence supports a dysregulation of the CXCR4/CXCL12 chemotactic axis of HHT endothelial cells, we hypothesized that a similar phenomenon could occur on lymphocytes.

Methods

Eighteen HHT patients with history of severe infection (HSI) were matched in age and sex with 18 HHT without HSI and 18 healthy control subjects (HC). We assessed the cell count and the surface expression of CXCR4 and CD26 (CXCL12 inactivating peptidase) of circulating T-helper and T-cytotoxic lymphocytes (including naive, memory and activated subsets) and NK cells.

Results

The overall HHT group of 36 patients exhibited a reduction of circulating T-helper lymphocytes compared to HC (median: 517 vs. 1026 cells/mm³, p < 0.0001), correlated with age (r =  − 0.46, p = 0.005), requirement of intravenous iron or blood transfusions (median: 291 vs. 627 cells/mm³, p = 0.03) and CXCR4 surface expression (r = 0.353, p = 0.0345). CXCR4 and CD26 membrane expression were both decreased on HHT T-helper lymphocytes (median MFI ratio: 4.49 vs. 5.74 for CXCR4 and 3.21 vs. 4.33 for CD26, p = 0.03 and 0.0018 respectively) with an unchanged CXCR4/CD26 ratio. The HHT group with HSI had a higher CXCR4/CD26 ratio on the total T-lymphocyte population, as well as on the T-helper population and its naive subset (median on naive T-helper cells: 2.34 vs. 1.32, p = 0.0002).

Conclusions

Our findings support a dysregulation of the CXCL12/CXCR4 chemotaxis of T-helper lymphocytes in HHT patients, potentially linked to their T-helper lymphopenia and susceptibility to infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-02139-y.

Residual Viremia Is Linked to a Specific Immune Activation Profile in HIV-1-Infected Adults Under Efficient Antiretroviral Therapy

Chronic immune activation persists in persons living with HIV-1 even though they are aviremic under antiretroviral therapy, and fuels comorbidities. In previous studies, we have revealed that virologic responders present distinct profiles of immune activation, and that one of these profiles is related to microbial translocation. In the present work, we tested in 140 HIV-1-infected adults under efficient treatment for a mean duration of eight years whether low-level viremia might be another cause of immune activation. We observed that the frequency of viremia between 1 and 20 HIV-1 RNA copies/mL (39.5 ± 24.7% versus 21.1 ± 22.5%, p = 0.033) and transient viremia above 20 HIV-1 RNA copies/mL (15.1 ± 16.9% versus 3.3 ± 7.2%, p = 0.005) over the 2 last years was higher in patients with one profile of immune activation, Profile E, than in the other patients. Profile E, which is different from the profile related to microbial translocation with frequent CD38+ CD8+ T cells, is characterized by a high level of CD4+ T cell (cell surface expression of CD38), monocyte (plasma concentration of soluble CD14), and endothelium (plasma concentration of soluble Endothelial Protein C Receptor) activation, whereas the other profiles presented low CD4:CD8 ratio, elevated proportions of central memory CD8+ T cells or HLA-DR+ CD4+ T cells, respectively. Our data reinforce the hypothesis that various etiological factors shape the form of the immune activation in virologic responders, resulting in specific profiles. Given the type of immune activation of Profile E, a potential causal link between low-level viremia and atherosclerosis should be investigated.

High Expression of Fas/CD95 on CD4+ Circulating T Cells: An Exclusion Criterion in the Diagnosis of Mycosis Fungoides?

The aim of this 10-year monocentric prospective study was to determine a cut-off value of Fas/CD95 expression by peripheral blood CD4+ T lymphocytes in discriminating patients with mycosis fungoides from controls with cutaneous benign lymphocytic conditions. CD95 expression in peripheral blood CD4+ T lymphocytes was measured using flow cytometry in 330 patients referred for diagnosis: 104 with mycosis fungoides and 226 with eczema, psoriasis, drug reaction, etc. The sensitivity and specificity of different thresholds of CD95 expression were calculated regarding the final diagnosis of patients with mycosis fungoides or controls. CD95 expression higher than 30% reached a specificity of 91% in ruling out a diagnosis of mycosis fungoides, although overall CD95 expression was not significantly different from that of controls (p = 0.309) and sensitivity was very low (5%). Thus, peripheral CD95 expression higher than 30% could be used among the exclusion criteria in a multicomponent score for mycosis fungoides diagnosis.

The nucleoporin Mlp2 is involved in chromosomal distribution during mitosis in trypanosomatids

Nucleoporins are evolutionary conserved proteins mainly involved in the constitution of the nuclear pores and trafficking between the nucleus and cytoplasm, but are also increasingly viewed as main actors in chromatin dynamics and intra-nuclear mitotic events. Here, we determined the cellular localization of the nucleoporin Mlp2 in the 'divergent' eukaryotes Leishmania major and Trypanosoma brucei. In both protozoa, Mlp2 displayed an atypical localization for a nucleoporin, essentially intranuclear, and preferentially in the periphery of the nucleolus during interphase; moreover, it relocated at the mitotic spindle poles during mitosis. In T. brucei, where most centromeres have been identified, TbMlp2 was found adjacent to the centromeric sequences, as well as to a recently described unconventional kinetochore protein, in the periphery of the nucleolus, during interphase and from the end of anaphase onwards. TbMlp2 and the centromeres/kinetochores exhibited a differential migration towards the poles during mitosis. RNAi knockdown of TbMlp2 disrupted the mitotic distribution of chromosomes, leading to a surprisingly well-tolerated aneuploidy. In addition, diploidy was restored in a complementation assay where LmMlp2, the orthologue of TbMlp2 in Leishmania, was expressed in TbMlp2-RNAi-knockdown parasites. Taken together, our results demonstrate that Mlp2 is involved in the distribution of chromosomes during mitosis in trypanosomatids.

The bacterial-like HslVU protease complex subunits are involved in the control of different cell cycle events in trypanosomatids

The trypanosomatid parasites Leishmania and Trypanosoma are responsible for the most important WHO-designated neglected tropical diseases, for which the need for cost-effective new drugs is urgent. In addition to the classical eukaryotic 20S and 26S proteasomes, these unconventional eukaryotes possess a bacterial-like protease complex, HslVU, made of proteolytic (HslV) and regulatory (HslU) subunits. In trypanosomatids, two paralogous genes are co-expressed: HslU1 and HslU2. Conflicting reports have been published with respect to subcellular localization, functional redundancy and putative roles of the different subunits of this complex in trypanosomatids. Here, we definitively established the mitochondrial localization of HslVU in L. major procyclic promastigotes and of HslV in T. brucei bloodstream trypomastigotes, the latter being the form responsible for the disease in the mammalian host. Moreover, our data demonstrate for the first time the essential nature of HslVU in the bloodstream trypomastigotes of T. brucei, in spite of mitochondrial repression at this stage. Interestingly, our work also allows distinguishing a specific role for the different members of the complex, as HslV and HslU1 appear to be involved in the control of different cell cycle events. Finally, these data validate HslVU as a promising drug target against these parasitic diseases of wide medical and economical importance.

Peripheral blood T4 cell surface CCR5 density as a marker of activity in rheumatoid arthritis treated with anti-CD20 monoclonal antibody

The chemokine (C-C motif) receptor CCR5 and its ligand CCL5 play key roles in the intra-articular recruitment of peripheral blood mononuclear cells (PBMC) in rheumatoid arthritis (RA). Therefore, using quantitative cytofluorometry, we followed T4 cell surface CCR5 density in 27 subjects with RA before and after treatment with the anti-CD20 monoclonal antibody rituximab. We observed low T4 cell surface CCR5 densities before treatment, which correlated positively with disease activity, as determined using a disease activity score evaluated on 28 joints (DAS 28), and negatively with CCL5 mRNA concentrations in PBMC, contrasting with a high proportion of intracellular CCR5 molecules, a pattern compatible with ligand-induced CCR5 internalization. At 3 months post-treatment, CCL5 mRNA expression in PBMC declined, whereas T4 cell surface CCR5 densities increased proportionally to the decrease in DAS 28. Thus, peripheral blood T4 cell surface CCR5 density is a good surrogate marker of RA activity and of the efficiency of anti-CD20 therapy.

Inhibition of active nuclear transport is an intrinsic trigger of programmed cell death in trypanosomatids

The link between nucleocytoplasmic transport and apoptosis remains controversial. Nucleocytoplasmic exchange of molecules seems indeed essential for the initiation and execution of the apoptotic programme; but inhibition of nuclear transport factors may also represent a powerful apoptotic trigger. The GTPase Ran (together with its partners), first discovered to be essential in nucleocytoplasmic transport, has multiple key functions in cell biology, and particularly in spindle assembly, kinetochore function and nuclear envelope assembly. Among the Ran partners studied, NTF2 appears to be solely involved in nucleocytoplasmic transport. Here, we localised Ran and several of its partners, RanBP1, CAS and NTF2, at the nuclear membrane in the trypanosomatid Leishmania major. Remarkably, these proteins fused to GFP decorated a perinuclear 'collar' of about 15 dots, colocalising at nuclear pore complexes with the homologue of nucleoporin Sec13. In the other trypanosomatid Trypanosoma brucei, RNAi knockdown of the expression of the corresponding genes resulted in an apoptosis-like phenomenon. These phenotypes show that Ran and its partners have a key function in trypanosomatids like they have in mammals. Our data, notably those about TbNTF2 RNAi, support the idea that active nucleocytoplasmic transport is not essential for the initiation and execution of apoptosis, and, rather, the impairment of this transport constitutes an intrinsic signal for triggering PCD.

Cell surface CCR5 density determines the intensity of T cell migration towards rheumatoid arthritis synoviocytes

As we have recently shown that the number of CCR5 molecules at the cell surface determines the efficiency of its function as a chemokine receptor, we tested the hypothesis that cell surface CCR5 density could influence the intensity of T lymphocyte recruitment into the rheumatoid joint. For this purpose, we established two Jurkat cell line-derived clones that differed only by their cell surface CCR5 densities. We studied their chemotaxis towards TNF-alpha-transduced rheumatoid synoviocytes supernatant. The Jurkat cell subline that expressed the higher cell surface CCR5 density migrated more intensively towards the supernatant of TNF-alpha-transduced synoviocytes than the Jurkat cell subline that expressed a lower surface CCR5 density. Moreover, this migration was blocked by an anti-CCR5 mAb. The CCR5 density on T cell surface, which is constant over time for a given individual, but varies drastically from one individual to another, might thus be a factor determining the intensity of joint inflammation in the course of RA.

The strength of the chemotactic response to a CCR5 binding chemokine is determined by the level of cell surface CCR5 density

We have shown that the intensity of expression of the C-C chemokine receptor CCR5 at the single CD4(+) cell level strongly determines the efficiency of its function as a coreceptor for human immunodeficiency virus type 1. By analogy, we examined if the number of CCR5 molecules at the cell surface might determine its chemotactic response to CCR5 ligands. To test this hypothesis, we measured by flow cytometry the migration of primary human T cells towards the CCR5-binding chemokine CCL5 in vitro. First, we observed a dose-dependent blockage of this migration exerted by an anti-CCR5 monoclonal antibody. Second, we sorted peripheral blood mononuclear cells into five subpopulations expressing various cell surface CCR5 densities, and observed a correlation between the intensity of migration towards CCL5 and the level of CCR5 expression on these subpopulations. Third, we transduced CCR5(+) peripheral blood mononuclear cells with the CCR5 gene, and observed that the CCR5 over-expression induced an over-migration towards CCL5. Finally, we observed in healthy donors a correlation between the chemotactic response of peripheral blood CD8(+) T cell to CCL5 and their level of surface CCR5 expression. T-cell surface CCR5 density, which is constant over time for a given individual, but varies drastically among individuals, might therefore be an important personal determinant of T-cell migration in many biological situations where CCR5-binding chemokines play a role, such as graft rejection, T helper 1-mediated auto-immune diseases, and infectious diseases involving CCR5. Moreover, our data highlight the therapeutic potential of CCR5 antagonists in these situations.

Immunostimulants revisited: focus on the pharmacology of Ribomunyl

Ribomunyl is an immunostimulant that was developed and commercialized in the 1980s in France and has subsequently been made available in a large number of countries. The formulation is composed of proteoglycans from Klebsiella pneumoniae and of ribosomes from four of the most commonly encountered bacterial strains in recurrent respiratory tract infections. While it is obviously difficult to present a thorough summary of all historical data, here we revisit the mode of action of this immunostimulant and present a perspective in the context of the most recent data and hypotheses on the mechanisms of the antibacterial immune responses. We provide various examples of these mechanisms in innate immunity (phagocytosis, cell adhesion, dendritic cell maturation, Toll-like receptors, interferon production, proinflammatory cytokines, activation of natural killer cells), as well as in adaptative immunity (polyclonal activation of T and B cells, specific immunoglobulin A immune response in an integrated view of the mucosal immune system, and T helper type 1/type 2 [Th1/Th2] regulation and balance). The effect of this immunostimulant on anti-infectious responses can be explained, not only by a stimulation of the antibacterial defense directly assumed by innate immunity, but also by a stimulation of the specific (adaptative) immune response related to the activation of dendritic cells, of which the pivotal role in T-cell differentiation is already well known. This supports the potential of bacterial immunostimulants such as Ribomunyl in anti-infective therapy.

The efficiency of R5 HIV-1 infection is determined by CD4 T-cell surface CCR5 density through G alpha i-protein signalling

OBJECTIVE AND DESIGN

The intensity of replication of CCR5-using HIV-1 strains is highly dependent on the number of CCR5 molecules on the surface of CD4-positive T cells. The molecular mechanisms responsible for this phenomenon remained so far unclear. As CCR5 co-receptors are coupled to G alpha i and G alpha q proteins, we tested the hypothesis that the activation triggered through these proteins secondary to the interaction between the viral envelope and CCR5 could account for the effect of the level of CCR5 expression on HIV-1 production.

METHODS

We transduced the wild-type or a G-protein signalling-defective CCR5 gene into CD4/CCR5 HOS cells and peripheral blood mononuclear cells. The effect on cell activation in presence of a CCR5-binding chemokine and on HIV infection was monitored by measuring calcium mobilization and p24 antigen production, respectively. The role of G alpha i protein signalling was tested by adding pertussis toxin to the cell cultures or by transfecting small interfering (si) RNAs into the HOS cells.

RESULTS

The over-expression of the wild-type form, but not of a G-protein signalling-defective form of CCR5, on the surface of CCR5 expressing peripheral blood mononuclear cells markedly increased their infectability. In addition, both pertussis toxin and G alpha i 1-specific siRNA drastically inhibited R5 infection.

CONCLUSIONS

The signalling through G alpha i-protein induced upon R5 virion binding to CCR5 is responsible for the difference in HIV-1 infectability between CD4-positive T cells expressing low or high levels of cell surface CCR5 density. This observation sheds new light on the physiopathology of HIV infection, and opens new therapeutic opportunities targeting G alpha i signalling.

The expression of cytotoxic mediators is altered in mononuclear cells of patients with melanoma and increased by interferon-alpha treatment

BACKGROUND

The role of cytotoxic cells in the control of cancer is now well established.

OBJECTIVES

To evaluate the expression of perforin and granzyme A in cytotoxic cells of patients with melanoma and to look for a link between this expression and natural tumour progression; to check if interferon (IFN)-alpha administration increased expression of cytotoxic mediators; and to evaluate if this increase was correlated with the antitumoral effect of IFN-alpha.

METHODS

To determine in patients with melanoma the expression of the cytotoxic mediators perforin and granzyme A in peripheral blood natural killer (NK) and T cells, we used flow cytometry before and after IFN-alpha administration.

RESULTS

Compared with healthy volunteers, we observed in 82 patients a low percentage of NK cells harbouring perforin [75% (95% confidence interval (CI) 70-79) vs. 92% (95% CI 89-95), P < 0.001] and granzyme A [48% (95% CI 41-55) vs. 73% (95% CI 66-81), P < 0.001]. By contrast, a high percentage of T cells, and particularly of CD56+ T cells, expressed perforin [56% (95% CI 41-71) vs. 28% (95% CI 18-38), P < 0.001], whereas a low percentage of CD56+ T cells expressed granzyme A [30% (95% CI 24-36) vs. 54% (95% CI 43-65), P < 0.001]. In untreated patients, the percentage of CD56+ T cells expressing granzyme A was higher in progressors than in nonprogressors [49% (95% CI 39-58) vs. 16% (95% CI 0-33), P = 0.003]. We followed cytotoxic mediator expression in 17 patients treated with IFN-alpha. IFN-alpha administration increased granzyme A expression in NK cells [44% (95% CI 27-61) and 65% (95% CI 54-76) before and after treatment, respectively, P = 0.010], rather than perforin expression, whereas expression of both perforin [46% (95% CI 30-62), and 58% (95% CI 44-73), P = 0.112] and especially granzyme A [27% (95% CI 14-40) vs. 45% (95% CI 26-64), P = 0.016] was increased in CD56+ T cells after IFN-alpha administration. Yet, this effect was not correlated with the clinical response to IFN-alpha.

CONCLUSIONS

Thus, the expression of cytotoxic mediators is altered in cytotoxic cells of patients with melanoma, and increased under IFN-alpha administration.

G-protein signaling triggered by R5 human immunodeficiency virus type 1 increases virus replication efficiency in primary T lymphocytes

The binding of R5 envelope to CCR5 during human immunodeficiency virus type 1 (HIV-1) entry provokes cell activation, which has so far been considered to have no effect on virus replication, since signaling-defective CCR5 molecules have been shown to function normally as HIV-1 coreceptors on transformed cells or mitogen-stimulated T lymphocytes. As the background state of activation of these cells might have biased the results, we performed experiments using the same approach but with nonactivated primary T lymphocytes. We now report that the single R126N mutation in the DRY motif, involved in G-protein coupling, results in a signaling-defective CCR5 coreceptor with a drastically impaired capacity to support HIV-1 infection.

Diminished CD4+ T cell surface CCR5 expression in alcoholic patients

AIMS

The C-C chemokine receptors, particularly the CCR5, appeared to play an important role in T cell-mediated inflammatory reactions. The aim of our study was to assess the impact of chronic alcohol consumption on the in vivo CCR5 expression.

METHODS

Fourteen alcoholic men hospitalized for a detoxification programme were prospectively included and compared with 49 age-matched controls.

RESULTS

The CD4(+) T cell surface CCR5 densities were drastically lower in alcoholic patients [mean, 5319 molecules/cell; 95% confidence interval (CI) 4477-6162] as compared with CCR5 densities of the controls (10 944 molecules/cell [CI 9929-11959]; P < 10(-4)).

CONCLUSIONS

Chronic alcohol consumption is associated with a significant decrease of CCR5 expression, which could favour Th1/Th2 imbalance.

Specific Alteration of Peripheral Cytotoxic Cell Perforin Expression in Alcoholic Patients: A Possible Role in Alcohol-Related Diseases

BACKGROUND

The association between chronic alcohol consumption and an increasing risk of infectious and neoplastic disease is related to an impairment of cellular immunity. However, studies of the number and activity of lymphocyte subsets show highly variable results. The aim of this study was to assess the expression of perforin, one of the main molecular agents of T and natural killer (NK) cell-mediated cytotoxicity, in alcoholic patients without cirrhosis.

METHODS

Eighteen patients with chronic alcoholism were prospectively included and compared with 18 age- and sex-matched healthy volunteers. Signs of hepatic insufficiency or portal hypertension, viral co-infection, other serious medical illness, and immune-related medications were exclusion criteria. Lymphocyte phenotype was assessed, and perforin expression was analyzed by flow cytometry in CD3+CD56+ T cells and NK cells. Granzyme synthesis was also evaluated in 11 of the 18 patients and compared with that of 11 age- and sex-matched controls.

RESULTS

The mean number of white blood cells and lymphocytes was not different between the controls and alcoholic patients, whereas the mean number of NK cells was significantly decreased in alcoholic patients (110 +/- 79/mm3 versus 271 +/- 192/mm3; p < 0.03). Perforin expression in T CD3+/CD56+ and in NK cells was significantly decreased in alcoholic patients compared with controls: 16 +/- 3% vs. 36 +/- 4% (p < 0.03) and 65 +/- 15% vs. 78 +/- 9% (p = 0.04), respectively. The percentage of cells expressing granzyme was similar in both groups.

CONCLUSIONS

A decrease in perforin expression by cytotoxic cells could be a major factor in explaining the physiopathologic mechanisms of several alcohol-associated diseases.

Immunomodulation induced by Avène spring water on Th1- and Th2-dependent cytokine production in healthy subjects and atopic dermatitis patients

Avène spring water (ASW) is commonly used in France for treating atopic dermatitis and psoriasis. Previous works demonstrated modulation of cell membrane fluidity by ASW. The aims of the present study were (a) to investigate a possible in vitro effect of ASW on Th1- and Th2-dependent cytokine production using peripheral blood mononuclear cells from healthy individuals and (b) to investigate both the in vitro effect of ASW on AD patients' cells and the in vivo cellular and clinical modifications induced by a 3-week Avène Medical Spa water cure (AMSWC). The effect of ASW was tested on lymphocyte cultures, which were stimulated in vitro by various mitogens and a superantigen of staphylococcal origin. The lymphocyte proliferation and the production of the cytokines IL-2, IL-4 and IFN-gamma were tested. The results showed that ASW-containing medium enhanced the lymphoproliferative response to some mitogens. IL-2 and IFN-gamma production were also increased in stimulated culture supernatants. Conversely, ASW-containing medium induced a decrease in IL-4 production by normal peripheral blood lymphocytes. Furthermore, AMSWC was able to amend the clinical features as well as the immunological Th2 profile of atopic dermatitis.

Natural killer cell and alphabeta and gammadelta lymphocyte traffic into the liver graft immediately after liver transplantation

BACKGROUND

The persistence and migration of donor leukocytes has been well established, but cellular kinetics immediately after revascularization and the potential relevance of these different lymphocyte populations to spontaneous tolerance remain unclear. During the early hours of revascularization, there is a transitory "congestion" of the liver graft, which is evidence of an early phase that we have termed "first cellular contact."

METHODS

We have carried out by flow cytometry a prospective comparative study of the peak kinetics of lymphocyte subpopulations contained in: (a) peripheral blood and liver grafts at the time of multi-organ extraction from 14 brain-dead donors, (b) recipient peripheral blood before transplantation, and (c) recipient peripheral blood and liver grafts after (t=2 h) declamping and vascularization of the liver graft.

RESULTS

Before transplantation, the liver grafts contained large numbers of natural killer (NK) and NK-like cells with early lymphocyte activation. Immediately after revascularization, there was an influx of recipient NK and NK-like cells into the liver.

CONCLUSIONS

NK and CD3+CD56+ (NK-like) cells flooding into the liver graft immediately after revascularization could rapidly destroy allogeneic cells. However, spontaneous tolerance and the persistence of donor lymphocytes after orthotopic liver transplant could be a result of donor TCRalphabeta NK1.1 liver graft lymphocytes, which may be involved in the destruction of CD8+ T lymphocytes that would have received the apoptosis signal, and to NK and NK-like cell inhibition via inhibitory NK receptors. The decrease in gammadelta T lymphocytes in the two compartments suggests a mechanism of recirculation and capture in other lymphoid organs.

Intracytoplasmic Th1 and Th2 cytokines in rheumatoid arthritis blood and synovial tissue

In rheumatoid arthritis (RA), T cells have been proposed either as a main actor or as an epiphenomenon in such a primarily synoviocyte-driven disease. A major issue remains the remarkable paradox between the T cell infiltrate and the relative failure to detect definite markers of their activity. To determine the Th1/Th2 cytokine profile in RA synovium, we used a single cell flow cytometric assay for interleukin-2 (IL-2), interferon-gamma (IFN-gamma), IL-4 and IL-10 in paired peripheral blood (PB) and synovial tissue (ST) lymphocytes from RA and osteoarthritis (OA) patients and PB lymphocytes from healthy controls. Cytokines were undetectable in unstimulated PB and ST lymphocytes. More stimulated PB and ST CD4(+)lymphocytes produced IFN-gamma than IL-4, for all individuals tested. RA PB CD4(+)lymphocytes showed the same Th1 cytokine pattern as normal controls. No increase of such a Th1 profile was observed for ST lymphocytes. A specific recruitment of T CD4(+)lymphocytes in the rheumatoid inflamed synovium could not be concluded on the basis of these results.

Activated sub-populations of lymphocytes and natural killer cells in normal liver and liver grafts before transplantation

AIMS/BACKGROUND

The anatomic structure of the liver suggests that it is a place of intense trafficking between intra-hepatic and peripheral blood compartment leukocytes. Furthermore, the liver contains a large number of passenger leukocytes that may play a role in the appearance of donor-type microchimerism after transplantation. In this study, we aimed to define the principal lymphocyte sub-populations contained in donor peripheral blood and liver grafts and in normal liver removed during minimally invasive surgery.

METHODS

Liver biopsies were taken at the time of vascular clampage during liver extraction from donors in a brain dead state (GI: n=14). Normal liver biopsies were removed during minimaly invasive surgery (GII: n= 10).

RESULTS

We observed evidence of the presence of lymphocytic activation associated with the two major CD8+ lymphocyte and natural killer (NK) cell populations in the two groups, with a significant increase in TCRgammadelta-bearing lymphocyte receptors between normal liver and the liver graft.

CONCLUSIONS

The presence of activated leukocytes in the graft could have a fundamental role in induction of peripheral tolerance. This activation could be the result of a basic immunological response linked to the interaction of T cells and NK cells, and of secondary activation due to stress and the conditions necessary for organ removal from donors in a brain dead state.