This document is an international evidence-based guideline on the diagnosis and management of idiopathic pulmonary fibrosis, and is a collaborative effort of the American Thoracic Society, the European Respiratory Society, the Japanese Respiratory Society, and the Latin American Thoracic Association. It represents the current state of knowledge regarding idiopathic pulmonary fibrosis (IPF), and contains sections on definition and epidemiology, risk factors, diagnosis, natural history, staging and prognosis, treatment, and monitoring disease course. For the diagnosis and treatment sections, pragmatic GRADE evidence-based methodology was applied in a question-based format. For each diagnosis and treatment question, the committee graded the quality of the evidence available (high, moderate, low, or very low), and made a recommendation (yes or no, strong or weak). Recommendations were based on majority vote. It is emphasized that clinicians must spend adequate time with patients to discuss patients' values and preferences and decide on the appropriate course of action.

An Official ATS/ERS/JRS/ALAT Statement: Idiopathic Pulmonary Fibrosis: Evidence-Based Guidelines for Diagnosis and Management

Publisher Summary Studies of cytotoxicity by human lymphocytes revealed not only that both allogeneic and syngeneic tumor cells were lysed in a non-MHC-restricted fashion, but also that lymphocytes from normal donors were often cytotoxic. Lymphocytes from any healthy donor, as well as peripheral blood and spleen lymphocytes from several experimental animals, in the absence of known or deliberate sensitization, were found to be spontaneously cytotoxic in vitro for some normal fresh cells, most cultured cell lines, immature hematopoietic cells, and tumor cells. This type of nonadaptive, non-MHC-restricted cellmediated cytotoxicity was defined as “natural” cytotoxicity, and the effector cells mediating natural cytotoxicity were functionally defined as natural killer (NK) cells. The existence of NK cells has prompted a reinterpretation of both the studies of specific cytotoxicity against spontaneous human tumors and the theory of immune surveillance, at least in its most restrictive interpretation. Unlike cytotoxic T cells, NK cells cannot be demonstrated to have clonally distributed specificity, restriction for MHC products at the target cell surface, or immunological memory. NK cells cannot yet be formally assigned to a single lineage based on the definitive identification of a stem cell, a distinct anatomical location of maturation, or unique genotypic rearrangements.

Biology of natural killer cells.

Epidermal growth factor-related peptides and their receptors in human malignancies

Reactive oxygen species, antioxidants, and the mammalian thioredoxin system.

In search of the 'missing self': MHC molecules and NK cell recognition.

Natural killer (NK) cells have unique surface features and physiological characteristics and a selective ability to lyse some, but not other, target cells1,2. However, the basis of this selectivity remains obscure at both effector and target cell levels. Proposed specific NK-cell target moieties3–5 include glycolipids, and glycoproteins unrelated to the major histocompatibility complex, while malignant and certain normal cells have been found to be susceptible to NK-cell-mediated cytolysis6–8. There is good evidence that NK cells can inhibit the outgrowth of small numbers of transplanted tumour cells in vivo9,10 and can restrict the establishment of secondary metastasis11,12. It has thus been speculated that NK cells function as a primitive, thymus-independent immune system using phylogenetically preserved target structures to form a cell-mediated resistance barrier against the outgrowth of certain tumour cells1. The presence in the thymuses of neonatal mice and humans8,13 and in the marrow of human fetuses, of apparently normal cells which are quite sensitive to NK cells suggested that NK cells might have an increased ability to cause the lysis of cells at a particular stage of their differentiation. In agreement with this concept, embryonal carcinoma cells at various stages of differentiation display a strikingly different susceptibility to NK-cell-induced lysis14. Here only cell types representing early stages were sensitive to NK-cell-mediated cytolysis, whereas the more differentiated endodermal cell lines showed close to complete resistance. The above data would thus support the view that, in vivo, depending on the stage of differentiation, both normal and malignant cells are under surveillance by NK cells. Here we have considered the question of differentiation-related NK-cell susceptibility using defined cell lines known to undergo controlled differentiation in the presence of various agents. Three tumour cell-lines were investigated, and all demonstrated a striking positive correlation between a decrease in NK-cell susceptibility and the induction of differentiation by the various inducers. Our findings support the view that susceptibility to NK-cell mediated lysis may vary according to the stage of differentiation of the target cell.

Natural killer cells kill tumour cells at a given stage of differentiation.

Insulin-like growth factor I is a growth and survival factor in human multiple myeloma cell lines.

Different types of human cells which normally grow as monolayers or suspension cultures were tested for their capacity to form and grow as spheroids. Sixteen out of the 27 tested tumour cell lines formed spheroids. Nearly all of these spheroids also grew. With only two exceptions the doubling times were longer when the tumour cells grew as spheroids than when they grew in conventional mass culture. Eleven out of 13 tested human non-tumour cells formed small spheroids but of these only the spheroids of lymphoid origin could grow. These lymphoid cells grew faster when aggregated to spheroids than when in single-cell suspension culture. None of the other non-tumour cells, which normally grew as monolayers, could grow as spheroids. The normally monolayer-cultured tumour cells formed symmetrical spheroids with smooth surfaces while the normally suspension-cultured cells formed irregular spheroids with rough surfaces. All large spheroids had a necrotic centre surrounded by a shell of viable cells. The thickness of the viable cell layer varied depending on cell type. The shape and organization of cells within the spheroids also varied largely. The results show that many types of human cells can be cultured as spheroids and that a wide spectrum of morphological appearances and growth rates can be obtained.

Kenneth Nilsson

Papers

Natural killer cells kill tumour cells at a given stage of differentiation.

Insulin-like growth factor I is a growth and survival factor in human multiple myeloma cell lines.

Formation and growth of multicellular spheroids of human origin.

Rapamycin sensitizes multiple myeloma cells to apoptosis induced by dexamethasone.

IGF-1 receptor tyrosine kinase inhibition by the cyclolignan PPP induces G2/M-phase accumulation and apoptosis in multiple myeloma cells.