Background: Interstitial lung disease (ILD) is a frequent manifestation of connective tissue diseases (CTDs) and is associated with high morbidity and mortality. Clinical practice guidelines to standardise screening, diagnosis, treatment and follow-up for CTD-ILD are of high importance for optimised patient care. Methods: A European Respiratory Society and European Alliance of Associations for Rheumatology task force committee, composed of pulmonologists, rheumatologists, pathologists, radiologists, methodologists and patient representatives, developed recommendations based on PICO (Patients, Intervention, Comparison, Outcomes) questions with grading of the evidence according to the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) methodology and complementary narrative questions agreed on by both societies. For both PICO and narrative questions, the Evidence to Decision framework was used to formulate the recommendations. Results: The task force committee concluded with recommendations for 25 PICO and 28 narrative questions, regarding ILD in the context of systemic sclerosis, rheumatoid arthritis (RA), idiopathic inflammatory myopathies, Sjögren disease (SjD), systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). In four narrative questions, regarding screening and assessment of risk for ILD progression in MCTD, SjD and SLE and one PICO question regarding pirfenidone in CTD-ILD other than RA-ILD, the task force had insufficient evidence to support recommendations. Screening, diagnostic, monitoring and treatment algorithms were developed based on the recommendations and usual clinical practice. Conclusions: We provide practical guidance by evidence-based recommendations to clinicians for each of the CTDs. In many cases there is low certainty or absence of evidence and we encourage further research to fill these gaps.

Myeloid‐derived suppressor cells (MDSC) are a heterogeneous group of immature myeloid cells that exist at very low numbers in healthy subjects but can expand significantly in malignant, infectious, and chronic inflammatory diseases. These cells are characterized as early‐MDSCs, monocytic‐MDSCs, and polymorphonuclear‐MDSCs and can be studied on the basis of their immunophenotypic characteristics and their functional properties to suppress T‐cell activation and proliferation. MDSCs have emerged as important contributors to tumor expansion and chronic inflammation progression by inducing immunosuppressive mechanisms, angiogenesis and drug resistance. Most experimental and clinical studies concerning MDSCs have been mainly focused on solid tumors. In recent years, however, the implication of MDSCs in the immune dysregulation associated with hematologic malignancies, immune‐mediated cytopenias and allogeneic hemopoietic stem cell transplantation has been documented and the potential role of these cells as biomarkers and therapeutic targets has started to attract a particular interest in hematology. The elucidation of the molecular and signaling pathways associated with the generation, expansion and function of MDSCs in malignant and immune‐mediated hematologic diseases and the clarification of mechanisms related to the circulation and the crosstalk of MDSCs with malignant cells and other components of the immune system are anticipated to lead to novel therapeutic strategies. This review summarizes all available evidence on the implication of MDSCs in hematologic diseases highlighting the challenges and perspectives arising from this novel field of research.

Myeloid-derived suppressor cells (MDSCs) are immature cells of myeloid origin that have gained researchers’ attention, as they constitute promising biomarkers and targets for novel therapeutic strategies (i.e., blockage of development, differentiation, depletion, and deactivation) in several conditions, including neoplastic, autoimmune, infective, and inflammatory diseases, as well as pregnancy, obesity, and graft rejection. They are characterised in humans by the typical immunophenotype of CD11b⁺CD33⁺HLA-DR^–/low and immune-modulating properties leading to decreased T-cell proliferation, induction of T-regulatory cells (T-regs), hindering of natural killer (NK) cell functionality, and macrophage M2-polarisation. The research in the field is challenging, as there are still difficulties in defining cell-surface markers and gating strategies that uniquely identify the different populations of MDSCs, and the currently available functional assays are highly demanding. There is evidence that MDSCs display altered frequency and/or functionality and could be targeted in immune-mediated and malignant haematologic diseases, although there is a large variability of techniques and results between different laboratories. This review presents the current literature concerning MDSCs in a clinical point of view in an attempt to trigger future investigation by serving as a guide to the clinical haematologist in order to apply them in the context of precision medicine as well as the researcher in the field of experimental haematology.

Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of myeloid cells that suppress immune responses in cancer, infection, and trauma. They mainly act by inhibiting T-cells, natural-killer cells, and dendritic cells, and also by inducing T-regulatory cells, and modulating macrophages. Although they are mostly associated with adverse prognosis of the underlying disease entity, they may display positive effects in specific situations, such as in allogeneic hematopoietic stem cell transplantation (HSCT), where they suppress graft-versus-host disease (GVHD). They also contribute to the feto-maternal tolerance, and in the fetus growth process, whereas several pregnancy complications have been associated with their defects. Human umbilical cord blood (UCB) is a source rich in MDSCs and their myeloid progenitor cells. Recently, a number of studies have investigated the generation, isolation, and expansion of UCB-MDSCs for potential clinical application associated with their immunosuppressive properties, such as GVHD, and autoimmune and inflammatory diseases. Given that a significant proportion of UCB units in cord blood banks are not suitable for clinical use in HSCT, they might be used as a significant source of MDSCs for research and clinical purposes. The current review summarizes the roles of MDSCs in the UCB, as well as their promising applications.