We report on the characteristics of 21 patients with hepatosplenic ␥␦ T-cell lymphoma (HS␥␦TCL), an entity recognized since 1994 in the Revised European American Lymphoma (REAL) classification. Median age was 34 years. Patients had splenomegaly (n ‫؍‬ 21), hepatomegaly (n ‫؍‬ 15), and thrombocytopenia (n ‫؍‬ 20). Histopathologic findings were homogeneous and showed the presence of medium-sized lymphoma cells within the sinusoids of splenic red pulp, liver, and bone marrow. Marrow involvement was usually mild but could be demonstrated by phenotyping in all patients. Cells were CD3 ؉ CD5 ؊ , expressed the ␥␦ T-cell receptor, and had a nonactivated cytotoxic cell phenotype (TIA-1 ؉ ,

We studied de novo protein biosynthesis in platelets of normal adult donors and in newly formed platelets isolated from splenectomized patients with idiopathic thrombocytopenic purpura (ITP). After metabolic labelling of platelet proteins, performed with different radiolabelled amino acids or carbohydrates, a tenfold increase in incorporation of radioactivity into trichloroacetic-acid-precipitable material was obtained with ITP platelets compared to control platelets. Electron microscopic studies of ITP platelets revealed the presence of rough endoplasmic reticulum and polyribosomes, providing morphological evidence for protein synthesis. SDS-PAGE of radiolabelled ITP platelet proteins followed by autoradiography showed that [35S]methionine and [3H]leucine were incorporated into almost all Coomassie-blue-stained proteins whereas [3H]cdrbohydrates only labelled a few bands. Using crossed-immunoelectrophoresis we identified some of the labelled platelet compounds and demonstrated that major membrane glycoproteins (GPIb, IIb, ZIIa) and alpha-granule proteins, such as fibrinogen, thrombospondin, albumin and von Willebrand factor, were synthesized in newly formed circulating platelets.Human platelets play an essential role in hemostasis and thrombosis. Following vascular injury, platelets adhere to exposed subendothelial tissue, become activated and secrete the content of their storage organelles. Released alpha-granule proteins, such as fibrinogen, von Willebrand factor, thrombospondin and factor V, interact with specific platelet membrane receptors to induce aggregation, thrombin conversion and fibrin formation for eventual clot retraction [I], whereas released platelet-derived growth factors promote tissue repair processes [2].Since human platelets are anucleated cytoplasmic fragments of megakaryocytes with a short lifespan in the peripheral blood, synthesis of platelet proteins is thought to occur almost solely in the precursor cell, the megdkaryocyte. Platelet-specific membrane glycoproteins have indeed been identified in megakaryocytes [3 -61, which are also known to contain platelet-related proteins such as von Willebrand factor [7] [12]. However, the site of biosynthesis of some platelet alpha-granule proteins, such as thrombospondin, albumin or immunoglobulins [ 131, remains uncertain since several of these proteins are not specific to platelets and are synthesized by other cell types, e.g. hepatocytes, endothelial cells, fibroblasts or lymphocytes. Biosynthesis therefore could occur either in megakaryocytes, where the proteins are packaged into alpha granules for subsequent release from circulating platelets, or in other cell types followed by an active uptake of the preformed proteins by the megakaryocyte, or possibly in both megakaryocytes and other cells. stable messenger RNA derived from nucleated megakaryocytes is present in circulating platelets [14-251. This biosynthetic activity has, however, been considered to be rather vestigial. Recently Belloc et al. reported increased protein synthesis and larg...

We previously reported a strong IL4I1 gene expression in primary mediastinal B-cell lymphoma (PMBL) and recently identified the protein as a secreted L-phenylalanine oxidase, physiologically expressed by myeloid cells, which inhibits T-cell proliferation in vitro. Here, we analyzed the pattern of IL4I1 protein expression in 315 human lymphoid and nonlymphoid malignancies. Besides PMBL, IL4I1 expression in tumors was very frequent. IL4I1 was detected in tumorassociated macrophages from most of the tumors and in neoplastic cells from follicular lymphoma, classic and nodular lymphocyte predominant Hodgkin lymphomas and small lymphocytic lymphoma, three of which are germinal center derived. IL4I1-positive tumor cells were also detected in rare cases of solid cancers, mainly mesothelioma. The enzymatic activity paralleled protein expression, suggesting that IL4I1 is functional in vivo. Depending on the tumor type, IL4I1 may impact on different infiltrating lymphocyte populations with consequences on tumor evolution. In the particular case of follicular lymphoma cells, which are susceptible to antitumor cytotoxic T cells killing but depend on interactions with local T helper cells for survival, a high level of IL4I1 expression seems associated with the absence of bone marrow involvement and a better outcome. These findings plead for an evaluation of IL4I1 as a prognosis factor.