Absence of interferons-alpha and -gamma in renal lesions of systemic lupus erythematosus and membranous glomerulonephritis

Cytokine expression in lupus kidneys

Although far from complete, the picture of cytokines present in systemic lupus erythematosus (SLE) glomerulonephritis is already complex. Proinflammatory cytokines, such as TNF, IL-6, IL-1, and IL-18 are upregulated, as are both Th1 and Th2 cytokines, with different implications. In many instances, the local effects may be different from the systemic immunoregulatory ones. For some proinflammatory cytokines, and TNF in particular, the local proinflammatory ones may be more relevant to the disease. This may help solve discrepancies between different murine models of the disease and provide a better rationale for targeting certain cytokines in human SLE.

Major histocompatibility complex class I antigen expression, immunolocalization of interferon subtypes, and T cell-mediated cytotoxicity in myopathies

Major histocompatibility complex class I (MHC-I) expression on target cells is a prerequisite for antigen-specific T cell-mediated cytotoxicity (TCMC). Enhanced MHC-I expression has been attributed to interferons (IFNs) released from inflammatory cells. In previous studies, we found evidence of TCMC (invasion of non-necrotic muscle fibers by cytotoxic T cells) in polymyositis (PM) and in inclusion body myositis (IBM). We occasionally found evidence of TCMC in Duchenne dystrophy (DD) but not in dermatomyositis (DM). This study examines the relationships between TCMC, MHC-I expression, and IFN immunoreactivity in these diseases and normal controls. In controls, reactivity for MHC-I was confined to blood vessels. In all diseases, regenerating fibers expressed MHC-I. In IBM, PM and DD, all nonnecrotic muscle fibers invaded by CD8+ cells and some adjacent fibers expressed MHC-I. In DM, myriad muscle fibers expressed MHC-I but none were invaded by CD8+ cells. In all diseases, only a few mononuclear cells and no muscle fiber surfaces were immunoreactive for IFNs. We conclude that MHC-I expression on muscle fibers is necessary but not sufficient for TCMC in myopathy; that the biological significance of increased MHC-I expression in DM remains undefined; and that currently available and appropriately controlled immunocytochemical methods show no relationship between increased MHC-I expression on muscle fibers and local IFN synthesis by mononuclear cells.

Effect of interferon-gamma on the abnormality of T cell activation in NZB mice

It is known that New Zealand black (NZB) mice have a defect in the autoantigen recognition mechanism by T cells. The present study was carried out to examine whether the defect could be improved by normalizing the self Ia molecule expression on thymic reticuloepithelial cells (TRC) by using interferon-gamma (IFN-gamma). Syngeneic mixed lymphocyte reaction (SMLR) was used as an indicator of the mechanism of autoantigen recognition. In the reaction, T cells separated from the thymus were used as responders, and machrophages separated from the spleen were used as stimulators. When the responders were cultured with TRC, in which self Ia molecule expressions had been enhanced by IFN-gamma, for activation, the low level of SMLR in NZB mice was elevated close to the normal level. It was suggested, therefore, that IFN-gamma could normalize the defective autoantigen expression on TRC in NZB mice and improve the abnormal T cell activation against autoantigens.

An immunofluorescent method for identifying individual IFN-gamma-producing lymphocytes

An immunofluorescent staining method was developed for detecting human IFN-gamma-producing cells in single cell suspensions. Mononuclear leukocytes, stimulated in vitro to produce IFN-gamma, were fixed and made permeable. The cytoplasmic presence of IFN-gamma was visualized by indirect immunofluorescence using IFN-gamma-specific mouse monoclonal antibodies. The staining was found to be specific for IFN-gamma and allowed the detection of newly synthesized rather than internalized IFN-gamma molecules. The cytoplasmic fluorescence appeared locally in a polar, juxtanuclear position, which overlapped the Golgi apparatus, probably reflecting the glycosylation site of the newly formed IFN-gamma molecules. Two-colour staining experiments showed that the method is useful not only for the detection and enumeration but also for the phenotypic characterization of IFN-gamma-producing cells.