Modulating mesenchymal stromal cell function with cholesterol synthesis inhibitors.

There is increasing evidence that statins, inhibitors of 3-hydroxyl-3-methylglutaryl coenzyme A reductase, can effectively be used not only in the treatment of hypercholesterolemia, but also in other human disorders; indeed, statins have strong anti-inflammatory and immunomodulatory effects, so that they can influence the onset and outcome of inflammation and autoimmunity. On the other hand, it has been shown that statins can affect growth and survival of solid tumour and leukemic cells, thus they have been proposed in the treatment of neoplasias as multiple myeloma, in association with drugs, as thalidomide, known to act on the cancer microenvironment. In the current view, tumor microenvironment include many cell types that interact with tumor cells: among them, stromal and endothelial cells, macrophages and dendritic cells, the various types of lymphocytes such as NK cells, B and T cells. The interplay between all these cell populations, and the balance between these, determines whether there is a tumour cell growth promotion or inhibition. In haematological malignancies, such as multiple myeloma, chronic lymphocytic and myeloid leukemias and follicular lymphomas, the survival, drug-resistance and proliferation of leukemic cells have been shown to be largely dependent on a supportive microenvironment, so that some cellular components of it, mainly mesenchymal stromal cells, cancer associated fibroblasts and macrophages, are now proposed as targets of new therapies. Herein, we analyze the effects that statins can exert on cancer cells, stromal cells and human natural killer cells, to discuss whether they can be proposed as anti-cancer drugs.

MF-59 adjuvant influence on the functions of gammadelta T cells in HIV-1+ adults immunized with influenza seasonal vaccine.

INTRODUCTION: We previously reported that in HIV-1 infected patients circulating Vdelta1 T lymphocytes (Vdelta1) increase and proliferate in vitro in response to Candida albicans (Ca). Herein, we analysed the effects of MF59 adjuvant on the Vdelta1 T cell responses to hemagglutinin (HA) and Ca in HIV-1 seropositive and seronegative adults after influenzal vaccine, to clarify th molecular mechanisms triggered in vivo by an adjuvanted vaccine against influenza virus. MATERIALS AND METHODS: 58 seropositive (HIV-1+) and 48 seronegative (HIV-1-) subjects received influenzal vaccines containing or not the MF59 adjuvant. The follow-up of in vitro T cell proliferation and cytokine production (IL-17A, IL-22, IL-23, IL-6) to HA and Ca antigens were performed at different time points (at basal time and after 30 and 90 days from vaccination) by cytofluorimetric approaches. RESULTS: We confirmed that in HIV-1 infected individuals the Vdelta1 T cell subset is expanded in HIV-1 infected individuals and moreover the number of circulating Vdelta1 Tcells significantly enhanced in all HIV-1+ subjects on day 90 after influenza vaccination. Regard the follow-up of proliferative responses, the increments of CD3+ response to HA and Vdelta1 T cells to Ca in HIV-1+ individuals were detectable earlier on day 30 for MF59-vaccinated patients, instead on day 90 post-vaccination in HIV(+)-vaccinated without MF59 adjuvant. Of note, production of lL-17A and IL-22, two cytokines with anti-fungal activity, in response to Ca was enhanced (for IL-17A) or restored (for IL-22) by vaccination in HIV-1+ donors, mainly using the MF59-adjuvanted vaccine. Moreover, after vaccination IL-23 and IL-6 production increased in response to HA in the HIV+ and HIV- groups vaccinated with MF59 adjuvant. CONCLUSIONS: We suggest that in HIV-1 infected patients the circulating Vdelta1 T lymphocytes reactive to Ca upon challenge with influenza virus vaccine receive an activating/enhancing signal mediated by cytokines triggered by the boost with HA antigen particularly in presence of MF59 adjuvant.

Gammadelta T lymphocytes producing IFNgamma and IL-17 in response to Candida albicans or mycobacterial antigens: possible implications for acute and chronic inflammation.

T lymphocytes bearing the gammadelta T cell receptor are known to play an important role in the first-line defense against viral, bacterial and fungal pathogens. Two main subsets of gammadelta T cells are known, showing distinct functional behaviour: Vdelta2 T lymphocytes, circulating in the peripheral blood, are involved in the response to mycobacterial infections and certain viruses, including coxsakie virus B3 and herpes simplex virus type 2. Vdelta1 T cells are resident in the mucosal-associated lymphoid tissue and are reported to participate in the immunity against Listeria monocytogenes and cytomegalovirus. Vdelta2 T lymphocytes recognize non-peptidic phosphorylated metabolites of isoprenoid biosynthesis, expressed by mycobacteria, while Vdelta1 T cells mainly interact with MHC-related antigens (MIC-A and MIC-B) and with receptors, called UL-16 binding proteins, for the UL-16 protein produced by cytomegalovirus-infected cells. Both Vdelta1 and Vdelta2 T cells can produce interferon-gamma in response to MIC-A(+) cells or non-peptide antigens, respectively. Moreover, production of TNF-alpha by human Vgamma9/Vdelta2 T cells has been demonstrated in response to bacterial products and non-peptidic molecules. Recently, it has been reported that gammadelta T lymphocytes can produce IL-17 during Escherichia coli or Mycobacterium tuberculosis infections in mice. This is of interest as IL-17 is emerging as a cytokine crucial in the control of intracellular pathogens and fungi. In this review, we will discuss the possible role of IL-17 producing gammadelta T cells in the regulation of acute and chronic inflammation, focusing on the different response of the two subsets to mycobacterial, viral or fungal antigens.

Effective in vivo induction of NKG2D ligands in acute myeloid leukaemias by all-trans-retinoic acid or sodium valproate.

Engagement of NKG2D by their ligands (NKG2D-L), as the human major histocompatibility complex class I-related molecules MIC-A and the UL16-binding proteins, on cytolytic lymphocytes leads to the enhancement of antitumour effector functions. These ligands are missing or expressed at very low levels on leukaemic cells; furthermore, they can be shed by tumour cells and inhibit cytolytic activity of lymphocytes. Herein, we show that in vivo administration of all-trans-retinoic acid (ATRA) or the histone deacetylase inhibitor sodium valproate (VPA) to patients affected with acute myeloid leukaemia (AML) M3 or M1 respectively, leads to the induction of transcription and expression of NKG2D-L at the surface of leukaemic cells. Apparently, no detectable shedding of the soluble form of these molecules was found in patients' sera. Conversely, AML blasts from patients treated with chemotherapy not including ATRA or VPA did not show any induction of NKG2D-L transcription. Furthermore, upon therapy with ATRA or VPA, leukaemic blasts become able to trigger lytic granule exocytosis by autologous CD8(+) T and natural killer lymphocytes, as shown by CD107a mobilization assay, followed by leukaemic cell lysis. These findings indicate that ATRA and VPA may contribute to the activation of cytolytic effector lymphocytes in vivo, possibly enhancing their anti-leukaemic effect.

Lack of the leukocyte-associated Ig-like receptor-1 expression in high-risk chronic lymphocytic leukaemia results in the absence of a negative signal regulating kinase activation and cell division.

In this study, we analysed 30 patients with B-cell chronic lymphocytic leukaemia (CLL), compared with 10 healthy donors, for the expression and function of the leukocyte-associated Ig-like receptor-1 (LAIR-1). LAIR-1 is an inhibitory receptor containing a cytoplasmic tyrosine-based inhibitory motif (ITIM) that binds to the SH2 domain of phosphatases, leading to dephosphorylation of different kinases. Constitutive activation of c-Jun aminoterminal kinase (JNK), p38 mitogen-activated protein kinase and extracellular signal-regulated kinase, has been reported in CLL. We show that LAIR-1 is absent in high-risk (HR) CLL and differently expressed on intermediate- and low-risk CLL and the intensity of expression, which is always significantly lower than in healthy donors, correlates with disease stage and progression. Interestingly, both constitutive and sIgM-induced phosphorylation of p38 and JNK is inhibited by LAIR-1 through an ITIM-dependent signal, as demonstrated by the use of specific ITIM-binding peptides; importantly, this inhibitory signal is missing when LAIR-1 is not expressed as occurs in HR CLL. Moreover, engagement of LAIR-1 blocks constitutive and sIgM-induced Akt phosphorylation, besides nuclear factor kappa-B nuclear translocation, and prevents CLL division. These results suggest that CLL lacking LAIR-1 may miss one of the molecular mechanisms controlling B-cell activation and proliferation.

Migratory pathways of gammadelta T cells and response to CXCR3 and CXCR4 ligands: adhesion molecules involved and implications for multiple sclerosis pathogenesis.

Gammadelta T lymphocytes are thought to be involved in multiple sclerosis (MS) pathogenesis. In this work, we discuss the characteristics of these cells and possible implications in the pathogenesis of MS, focusing on the mechanism(s) underlying extravasation and tissue localization. Phenotype and transendothelial migration of gammadelta T cells from healthy donors and patients with relapsing-remitting MS were studied. In MS patients the V delta 2 T cell subset, expressing NKRP1A/CD161 adhesion molecule, is expanded and capable of transendothelial migration. V delta 1/V delta 2 subsets use distinct signal transduction pathways: V delta 1 cells lack NKRP1A and express PECAM-1/CD31, which drives transmigration, while V delta 2 cells are PECAM-1 negative and use NKRP1A. V delta 2 migration is coupled with CAMKII, whereas V delta 1 depend on PI-3K. NKRP1A and PECAM-1 selectively activate the two pathways: indeed, oligomerization of NKRP1A on V delta 2 T cells leads to CAMKII activation, occupancy of PECAM-1 on V delta 1 cells triggers the PI-3K-dependent Akt/PKB pathway. Moreover, V delta 2 T cells are CXCR3(bright)CXCR4(dull), while V delta 1 are mostly CXCR4(+). V delta 1 and V delta 2 cells transmigrate in response to IP-10/CXCL10 and SDF-1/CXCL12 according to the expression of their specific receptors. In a fraction of V delta 1 T cells coexpressing CXCR3 and CXCR4, the homeostatic chemokine 6Ckine/SLC/CCL21 is more effective. IP-10/CXCL10 or 6Ckine/SLC/CCL21 and SDF-1/CXCL12-induced transmigration is coupled to PI-3K/Akt/PKB, but only CXCR3 is capable of inducing CAMKII activation. We suggest that both subsets of gammadelta T lymphocytes may migrate to the site of lesion in MS using two different signaling pathways to extravasate and responding to different chemokines.

In vivo apoptosis of CD8(+) lymphocytes in acute myeloid leukemia patients: involvement of soluble HLA-I and Fas ligand.

In this study, we show that high serum levels of soluble human leukocyte antigens (HLA) class I molecules (sHLA-I, range: 0.7-1.7 micro g/ml) and soluble Fas ligand (FasL, range: 0.4-1.9 ng/ml) are detected in patients with acute myeloid leukemia (AML) at diagnosis, compared with healthy donors (HD) (sHLA-I, range: 0.1-0.6 micro g/ml; sFasL, range: 0.1-0.4 ng/ml). Patients' sera were able to induce transcription and secretion of FasL in CD8(+) T cells, followed by apoptosis in vitro; this apoptosis was inhibited by anti-HLA-I-specific monoclonal antibodies, suggesting that sHLA-I is responsible for cell death. These findings closely relate to the in vivo upregulation of FasL transcription observed in peripheral blood (PB) lymphocytes from AML patients; in the same cells, mRNA for the antiapoptotic proteins Bcl-2 and Bcl-x(L) was downregulated. Interestingly, caspase-8 and caspase-3, both downstream mediators of death receptor-induced apoptosis, were activated in CD8(+) cells of AML patients; one-third of these cells were already apoptotic in vivo, at variance with lymphocytes of HD. These data strongly suggest that in AML, increased levels of sHLA-I molecules may contribute to the elimination of potentially anti-tumor effector cells through a FasL/Fas interaction.

ZAP-70 is expressed by normal and malignant human B-cell subsets of different maturational stage.

ZAP-70 tyrosine kinase is involved in signalling pathways following T-cell receptor stimulation and was originally described only in T cells and natural killer cells. ZAP-70 expression has been reported in normal mouse B lineage cells and in human malignant B lymphocytes, mainly in chronic lymphocytic leukemia (CLL) where it correlates with clinical outcome. We analyzed several B-cell lines and ex vivo malignant B cells, ranging from acute lymphoblastic leukemia to multiple myeloma and reflecting different stages of B-cell differentiation, and they showed ZAP-70 expression regardless their maturation stage. We then analyzed by Western blot and flow cytometry different human normal B-lymphocyte subpopulations: naïve, germinal center and memory B cells from tonsils, CD19+ CD5+ cells from cord blood and CD19+ lymphocytes from peripheral blood. All expressed ZAP-70 protein, though at different levels depending on their differentiation, activation and tissue localization. In addition, ZAP-70 expression levels could be modulated following stimulation via the B-cell receptor. These findings implicate a potential role of ZAP-70 in the signalling pathway of B lymphocytes at different maturational stages, indicate that ZAP-70 expression is not a CLL-specific feature among B-cell malignancies and suggest that the absence of ZAP-70 rather than its presence should be considered abnormal for malignant B lymphocytes.

Leukocyte-associated Ig-like receptor-1 prevents granulocyte-monocyte colony stimulating factor-dependent proliferation and Akt1/PKB alpha activation in primary acute myeloid leukemia cells.

The leukocyte-associated Ig-like receptor-1 (LAIR-1), a surface leukocyte receptor containing two immune receptor tyrosine-based inhibitory motif (ITIM) is expressed on acute myeloid leukemia (AML) blasts isolated from peripheral blood or bone marrow of 17 patients (2 M0, 3 M1, 5 M2, 2 M4 and 5 M5 according to French, American and British classification). Further, we provide evidence thatLAIR-1 engagement inhibits granulocyte-monocyte colony-stimulating factor (GM-CSF)-induced proliferation of AML blasts. Indeed, leukemia cells stimulated with GM-CSF were blocked in the G0/G1 phase of the cell cycle and underwent apoptosis within 4 days after the engagement of LAIR-1. Remarkably, LAIR-1 was functional also in AML blasts which do not express CD33, mainly M4 and M5. Importantly, the LAIR-1 ligation led to a strong inhibition of both GM-CSF receptor-mediated intracellular calcium increases, phosphorylation and activation of Akt1/protein kinase B alpha, a substrate of the phosphatidylinositol-3 kinase. This last inhibitory effect was prevented by a synthetic peptide spanning the ITIM portion of LAIR-1, suggesting the involvement of SHP-1 phosphatase in LAIR-1-mediated inhibitory signal. Altogether, these findings indicate that the engagement of LAIR-1 can down-regulate GM-CSF-mediated survival and proliferation of AML blasts, suggesting an additional therapeutic approach to the treatment of AML patients.

Roles of tumor necrosis factor p55 and p75 receptors in TNF-alpha-induced vascular permeability.

We have investigated the role of p55 and p75 tumor necrosis factor receptors 1 and 2 (TNFR1 and TNFR2, respectively) in TNF-induced alteration of endothelial permeability in vitro and in vivo. Stimulation of TNFR1 with an agonist antibody or a receptor-selective TNF mutein increased the flux of (125)I-albumin through endothelial cell monolayers. An antagonist anti-TNFR1 antibody, but not antagonist anti-TNFR2 antibodies, blocked the activity of TNF in vitro. Stimulation of TNFR1, but not TNFR2, induced cytoskeletal reorganization associated with increased permeability. SB-203580, a p38 mitogen-activated protein kinase inhibitor, blocked TNFR1-induced cytoskeletal reorganization and permeability. A selective mouse TNFR1 agonist and human TNF, which binds to murine TNFR1, increased the leakage of trypan blue-albumin from liver vessels in mice. These results indicate that stimulation of TNFR1 is necessary and sufficient to increase endothelial permeability in vitro and in vivo. However, an antagonist anti-murine TNFR2 antibody partially inhibited the effect of murine TNF on liver vessels, suggesting that TNFR2 also plays a role in the regulation of TNF-induced vascular permeability in vivo.

CD8(+) T lymphocytes induce polarized exocytosis of secretory lysosomes by dendritic cells with release of interleukin-1beta and cathepsin D.

We recently reported that human dendritic cells release the leaderless secretory protein interleukin-1beta (IL-1beta) following specific interaction with alloreactive T lymphocytes. To clarify the molecular mechanism underlying this secretion, this study investigated the intracellular trafficking of IL-1beta in dendritic cells and the signal(s) regulating its release. Results show that a fraction of the intracellular IL-1beta precursor colocalizes with the hydrolase cathepsin D in endolysosomes of dendritic cells; secretion of both proteins is elicited by stimuli that induce intracellular calcium increases. Alloreactive CD8(+) T lymphocytes generate a Ca(++) influx in dendritic cells followed by enrichment in endolysosomes containing IL-1beta and cathepsin D beneath the membrane in contact with T cells. These events result in polarized exocytosis of secretory lysosomes, mediated by microtubules, with release of IL-1beta and cathepsin D toward the interacting CD8(+) T cell.

NK cell-mediated lysis of autologous antigen-presenting cells is triggered by the engagement of the phosphatidylinositol 3-kinase upon ligation of the natural cytotoxicity receptors NKp30 and NKp46.

Interleukin-2 (IL-2)-activated polyclonal or clonal NK cells lysed autologous antigen presenting cells (APC) through the engagement of the natural cytotoxicity receptors (NCR) NKp30 and NKp46. NK cell-mediated cytolysis of APC correlated with the surface density of these NCR. Indeed, NK cell clones bearing low amounts of NKp30 and NKp46 did not lyse autologous APC, whereas NK cell clones with bright expression of these NCR efficiently killed autologous APC. Upon masking of NKp30 or NKp46 by specific monoclonal antibodies a strong reduction (by 50%) of APC lysis could be detected and the complete inhibition was achieved by the simultaneous masking of these NCR. Interestingly, NK cell-mediated APC lysis was impaired by the phosphatidylinositol 3-kinase (PI-3 K) inhibitors LY294002 or wortmannin. Similarly, these drugs strongly reduced NK cell activation triggered by NKp30 or NKp46 in a re-directed killing assay as well as the activation of Akt/PKB, substrate of PI-3 K, induced by the engagement of these receptors. Altogether, these findings strongly suggest that NCR are responsible for the killing of autologous APC through the activation of PI-3 K.

Engagement of the leukocyte-associated Ig-like receptor-1 induces programmed cell death and prevents NF-kappaB nuclear translocation in human myeloid leukemias.

Leukocyte-associated Ig-like receptor-1 (LAIR-1) is a surface molecule that functions as an inhibitory receptor on natural killer cells, T lymphocytes and monocytes. Here, we provide evidence that occupancy of LAIR-1 on human myelomonocytic leukemic cell lines inhibits proliferation and leads to programmed cell death (PCD), evaluated by propidium iodide staining and transmission electron microscopy. Interestingly, PCD elicited via LAIR-1 was not blocked by different caspase inhibitors, at variance with apoptosis induced via CD95/Fas, which was prevented by the caspase-1 and caspase-8 specific inhibitors. In addition, we show that the p65 subunit of the nuclear factor kappaB (NF-kappaB), constitutively expressed in the nucleus of these cell lines, was retained in the cytoplasm upon engagement of LAIR-1. This was evident already 8 h after LAIR-1 occupancy, when apoptosis was not yet detectable by fluorometric or ultrastructural analysis. Moreover, a reduction in inhibitor kappaBalpha phosphorylation was observed after LAIR-1 engagement. As blocking of NF-kappaB activation has been shown to rescue sensitivity to anti-cancer drugs in solid tumors, we suggest that LAIR-1 may represent a possible target for pharmacological approaches aimed to potentiate anti-leukemic therapy.

Control of interleukin-18 secretion by dendritic cells: role of calcium influxes.

Here we show that dendritic cells accumulate the precursor form of the leaderless secretory protein interleukin-18 (pro-interleukin-18) in the cell cytosol and in organelles co-fractionating with endolysosomes. Upon antigen specific contact with T lymphocytes, particulated pro-interleukin-18 decreases rapidly, and the cytokine appears extracellularly, suggesting that exocytosis of pro-interleukin-18-containing organelles is induced. Exocytosis of secretory lysosomes is modulated by calcium: in agreement with this, calcium influx results in secretion of pro-interleukin-18. In turn, pro-interleukin-18 secretion induced by T cells is prevented by the calcium channel blocker nifedipine. Our results demonstrate a novel, calcium-mediated mechanism of post-translational regulation of secretion for interleukin-18, that allows a fast release of the cytokine.

Secretion of bioactive interleukin-1beta by dendritic cells is modulated by interaction with antigen specific T cells.

The role of interleukin-1beta (IL-1beta) as a regulator of the immune response, although extensively investigated, is still debated. We then studied the expression of IL-1beta by human dendritic cells (DCs), the professional antigen presenting cells, and its modulation during immune reactions in vitro. Our results show that, on maturation or tetanus toxoid presentation to specific CD4(+) CD40L(+) T lymphocytes, DCs begin to accumulate IL-1beta precursor (pro-IL-1beta) but do not secrete bioactive IL-1beta. In contrast, interaction with alloreactive T cells results in both stimulation of pro-IL-1beta synthesis and secretion of processed isoforms of the cytokine, that display biologic activity. Both CD4(+) and CD8(+) subsets of allospecific T lymphocytes are required: CD4(+) T cells drive the synthesis of pro-IL-1beta through CD40 engagement but have no effects on pro-IL-1beta processing; CD8(+) T cells, unable to induce synthesis of pro-IL-1beta per se, are responsible for the generation of mature IL-1beta by pro-IL-1beta-producing DCs. Interleukin-1beta-converting enzyme (ICE) inhibitors do not prevent the recovery of IL-1beta bioactivity after allorecognition, indicating that allospecific CD8(+) T cells may induce the release of bioactive IL-1beta via mechanism(s) other than ICE activation. Altogether, these findings suggest that CD4(+) and CD8(+) T-lymphocyte subsets have distinct roles in the induction of IL-1beta secretion by DCs and support the hypothesis that IL-1beta plays a role in cell-mediated immune responses. (Blood. 2000;95:3809-3815)

uPA/uPAR system is active in immature dendritic cells derived from CD14+CD34+ precursors and is down-regulated upon maturation.

We recently described a subset of peripheral CD14+CD34+ cells able to migrate across endothelial cell monolayers and differentiate into immunostimulatory dendritic cells (DC). In this paper we show that immature DC derived from CD14+CD34+ precursors are also capable of reverse transendothelial migration and extracellular matrix (ECM) invasion using the urokinase plasminogen activator receptor (uPAR). We found that these cells respond to macrophage-inflammatory protein (MIP)-1alpha, enhancing their ability to invade ECM and supporting the idea that immature DC are selectively recruited at the site of inflammation to expand the pool of APCs. Interestingly, MIP-1alpha was also capable of preventing the decreased matrix invasion observed by blocking uPAR, suggesting that the uPA/uPAR system and MIP-1alpha cooperate in driving immature DC migration through the subendothelial matrix. Upon exposure to maturating stimuli, such as TNF-alpha, CD14+CD34+-derived DC enhance their APC function and decrease the capacity of invading ECM; these changes are accompanied by altered expression and function of uPAR. Moreover, mature DC shift their sensitivity from MIP-1alpha to MIP-3beta, enhancing their transendothelial migration capability in response to the latter chemokine. Our data support the hypothesis that bloodborne DC can move through ECM toward the site of pathogen entry where they differentiate into fully mature APCs with their motility and function regulated by microenvironmental stimuli, including MIP-1alpha, MIP-3beta, and TNF-alpha.

Interleukin-18 synthesis and secretion by dendritic cells are modulated by interaction with antigen-specific T cells.

We show that interleukin-18 is constitutively produced by dendritic cells; synthesis and secretion are poorly affected by maturative stimuli. Challenge of dendritic cells with autologous anti-tetanus toxoid T lymphocytes results in a secretory switch, with induction of secretion of biologically active interleukin-18 and decrease of its intracellular content. Similarly, when dendritic cells are challenged with allospecific T cells a dramatic decrease of intracellular interleukin-18 content occurs, whereas no effects are observed after co-culture with autologous activated T cells. The induction of secretion call be mediated by engagement of CD40 on dendritic cells, as indicated by the increased amount of interleukin-18 in dendritic cell supernatants after CD40 triggering by anti-CD40 antibodies. However, CD40 engagement, unlike from antigen-specific T cells, does not result in reduced intracellular interleukin-18 content, suggesting that this decrease may be mediated by structure(s) involved in antigen recognition.

IL-12-mediated NKRP1A up-regulation and consequent enhancement of endothelial transmigration of V delta 2+ TCR gamma delta+ T lymphocytes from healthy donors and multiple sclerosis patients.

Gamma delta T lymphocytes are thought to play a role in the pathogenesis of multiple sclerosis (MS) contributing to demyelinization and fibrosis in the central nervous system. In this study, we show that, in MS patients with active disease, the percentage of circulating V delta 2+ gamma delta T cells coexpressing NKRP1A is significantly increased compared with healthy donors. V delta 2+ and V delta 1+ T cells were sorted from MS patients and healthy volunteers and cloned. At variance with V delta 1+ clones, all V delta 2+ clones expressed NKRP1A, which was strongly up-regulated upon culture with IL-12; this effect was neutralized by specific anti-IL-12 Abs. No up-regulation of NKRP1A by IL-12 was noted on V delta 1+ clones. RNase protection assay showed that IL-12R beta 2 subunit transcript was significantly less represented in V delta 1+ than V delta 2+ clones. This finding may explain the different effect exerted by IL-12 on these clones. In transendothelial migration assays, V delta 2+ NKRP1A+ clones migrated more effectively than V delta 1+ clones, and this migratory potential was enhanced following culture with IL-12. Migration was strongly inhibited by the F(ab')2 of an anti-NKRP1A Ab, suggesting that this lectin is involved in the migration process. We also show that, in freshly isolated PBMC from MS patients, the migrated population was enriched for V delta 2+ NKRP1A+ cells. We conclude that the expression of NKRP1A on V delta 2+ cells is associated with increased ability to migrate across the vascular endothelium and that this phenomenon may be regulated by IL-12 present in the microenvironment.