CD99 has been reported to be involved in T cell regulation. CD99 ligand involvement in the regulation of T cell activation has been postulated. In this study, recombinant CD99 proteins were produced and used as a tool for determining the role of CD99 and its ligand interaction. Recombinant CD99 proteins induced the upregulation of IL-6 and TNF-α expression, but not IFN-γ, in anti-CD3 monoclonal antibody activated T cells. The cytokine alteration was not observed in unstimulated T cells indicating the cytokine upregulation required the signal from T cell activation. The upregulation of IL-6 and TNF-α was, in addition, observed in CD3- mononuclear cell population including monocytes and NK cells. The recombinant CD99 proteins, however, did not affect either CD25, CD69 or MHC class II expression or T cell proliferation, upon T cell activation. The CD99 ligands were demonstrated to be expressed on monocytes, NK cells and dendritic cells, but not on B and T cells. Our results indicated the presence of CD99 ligands on leukocyte surface. Interaction between CD99 and its ligands involves the regulation of cytokine production.

Systemic sclerosis (SSc) is a connective tissue disease that is characterized by widespread skin and internal organ fibrosis vasculopathy and immune response abnormalities, including T, B, natural killer (NK), and natural killer T (NKT) cell involvement. The aim of the study was to investigate the immune cell profile in patients with systemic sclerosis in relation to the disease activity, severity, and antibody presence and their relation to the type of immunosuppressive treatment. Cytometric examination identified following cell lines: B cells (Breg, B memory, B mature) and plasmablasts, T cell, T double positive-Tdp, T double negative-Tdn, NK, and NKT cell and monocytes. The disease severity and activity were assessed based on the Medsger and the EULAR Scleroderma Trials and Research Group (EUSTAR) 2017 scales respectively. In the study, SSc patients were characterized by higher total lymphocyte count parallel to increased frequency of Ts and Th cells. In SSc patients, increment of Tdp and reduction of Tdn as well as NK and NKT cells were observed. Additionally in SSc patients the reduction of B memory was noted. Head to head comparison between cyclophosphamide (CYC) and mycophenolate mofetil (MMF) treatment showed a reduction of CD19+ cells, but increment of plasmablasts in CYC treated patients.

Ascites is a prominent feature of ovarian cancer and could serve as liquid biopsy to assess the immune status of patients. Tumor-infiltrating T lymphocytes are correlated with improved survival in ovarian cancer. To investigate whether immune cells in ascites are associated with patient outcome, we analyzed the amount of dendritic cell (DC) and T cell subsets in ascites from ovarian cancer patients diagnosed with high-grade serous cancer (HGSC). Ascites was collected from 62 HGSC patients prior to chemotherapy. Clinicopathological, histological and follow-up data from patients were collected. Ascites-derived immune cells were isolated using density-gradient centrifugation. The presence of myeloid DCs (BDCA-1+, BDCA-3+, CD16+), pDCs (CD123+BDCA-2+), and T cells (CD4+, CD8+) was analyzed using flow cytometry. Complete cytoreduction, response to primary treatment and chemosensitivity were associated with improved patient outcome. In contrast, immune cells in ascites did not significantly correlate with patient survival. However, we observed a trend toward improved outcome for patients having low percentages of CD4+ T cells. Furthermore, we assessed the expression of co-stimulatory and co-inhibitory molecules on T cells and non-immune cells in 10 ascites samples. PD-1 was expressed by 30% of ascites-derived T cells and PD-L1 by 50% of non-immune cells. However, the percentage of DC and T cell subsets in ascites was not directly correlated to the survival of HGSC patients.

Myelodysplastic syndromes (MDSs) are clonal disorders of hematopoietic stem cells (HSCs) characterized by ineffective hematopoiesis. MDSs are responsible for 1 or several peripheral cytopenias. The evidence accumulated in recent years demonstrates that in addition to HSC defects, a particular role is also played by stromal microenvironment dysfunctions, which mediate the direct contact with hematopoietic precursor cells (HPCs). These interactions help regulate different adhesion-related processes, such as progenitor cell proliferation, apoptosis, clonogenic growth, and maintenance in in vitro cultures. As previously reported, these interactions are responsible for altering the microenvironment in MDS. Herein, we present a novel selection protocol for obtaining a standards-compliant mesenchymal stromal cell (MSC) preparation. This method allowed us to comparatively analyze 2 subpopulations of bone marrow MSCs (BM-MSCs) in terms of their adhesion profiles and growth abilities: BM-MSCs selected from MDS settings and their normal counterparts. Functional assays revealed that the MSCs from MDS are intrinsically pathological, thus showing a continuous decline of proliferation and a reduced clonogenic capacity during 14 days of culture and in the absence of signals from hematopoietic cells. The MSC growth defects were significantly correlated with decreases in CD44 adhesion molecules and CD49e (α5-integrin).

CD248 (endosialin) is a transmembrane glycoprotein that is dynamically expressed on pericytes and fibroblasts during tissue development, tumour neovascularization and inflammation. Its role in tissue remodelling is associated with increased stromal cell proliferation and migration. We show that CD248 is also uniquely expressed by human, but not mouse (C57BL/6), CD8(+) naive T cells. CD248 is found only on CD8(+) CCR7(+) CD11a(low) naive T cells and on CD8 single-positive T cells in the thymus. Transfection of the CD248 negative T-cell line MOLT-4 with CD248 cDNA surprisingly reduced cell proliferation. Knock-down of CD248 on naive CD8 T cells increased cell proliferation. These data demonstrate opposing functions for CD248 on haematopoietic (CD8(+)) versus stromal cells and suggests that CD248 helps to maintain naive CD8(+) human T cells in a quiescent state.
© 2011 The Authors. Immunology © 2011 Blackwell Publishing Ltd.