Monoclonal antibody analysis of mononuclear cells in myopathies. III: Immunoelectron microscopy aspects of cell-mediated muscle fiber injury

Inflammatory and non-inflammatory inclusion body myositis. Characterization of the mononuclear cells and expression of the immunoreactive class I major histocompatibility complex product

In ten patients with inclusion body myositis (IBM) five muscular biopsies showed profuse inflammatory exudates and three showed a few scattered inflammatory cells with partial invasion in some muscle fibers. No inflammatory cells were seen in two cases. In all patients, histopathological, histomorphometric and immunocytochemical studies were performed. Immunocytochemistry for the class I and class II major histocompatibility complex gene product (MHC) was performed in all cases and in ten control muscles including: normal muscles [3], dermatomyositis [3], polymyositis [3], scleroderma [1]. In the five cases of IBM with inflammatory exudates, subsets of lymphocytes were analyzed with a panel of monoclonal antibodies against B cells, T4 cells, T8 cells, K and natural killer cells and macrophages. Some muscle fibers expressed class I MHC antigens in the inflammatory cases of IBM. These fibers were near the inflammatory exudates and occasionally showed a partial invasion. No expression of class I MHC was found in normal muscles and in non-inflammatory cases of IBM. The antigen which triggers the mononuclear cells in the inflammatory forms of IBM is probably not the filamentous inclusions in rimmed vacuoles. In other inflammatory myopathies, expression of class I MHC was present on all fibers in polymyositis, only in the perifascicular area in dermatomyositis and in scleroderma. It could be suggested that the term "inclusion body muscle disease" be applied to cases with rimmed vacuoles and "IBM-like" filaments without inflammatory cells.

Intracellular calcium in canine muscle biopsies

Intracellular staining for calcium was studied in muscle biopsies from 15 dogs by the alizarin red S (ARS) stain. Rare positive fibres were present in normal muscle and in denervation atrophy. The percentage of positive fibres was slightly increased in polymyositis, dermatomyositis and canine temporal/masseter myositis and markedly increased in progressive muscular dystrophy. Calcium-positive fibres were usually so-called large-dark (hypercontracted) fibres or necrotic fibres, although there was occasional staining of normal and atrophied fibres. These results indicate the probable involvement of calcium in muscle injury in canine inflammatory myopathies and in canine muscular dystrophy. In addition, use of the ARS stain appears to be useful for detecting the earliest lesions of acute muscle fibre injury.

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.

Ia-expressing microglial cells in experimental allergic encephalomyelitis in rats

Monoclonal antibodies (MRC OX-6 and OX-17) recognized three types of cells expressing Ia antigen during the course of acute experimental allergic encephalomyelitis (EAE) in rats. In earlier stages of the disease, in animals with or without paralysis, Ia antigens were mostly localized to subarachnoidal and perivascular lymphocytic and histiocytic cell infiltrates, possibly serving as antigen-presenting cells. On the other hand, in convalescent rats, Ia antigens were expressed in a large number of cells with dendritic processes heavily populating the spinal gray matter. The appearance of these Ia-expressing cells in the convalescent stage coincided with the development of degenerating axon terminals in the spinal gray matter. These Ia-expressing cells possessed morphological features characteristic of microglia and were positive for ML-1 lectin but did not express glial fibrillary acidic protein. Immune electron microscopy disclosed the presence of Ia reaction products in the Golgi apparatus, endoplasmic reticulum and plasma membrane of these cells with dendritic processes, indicating active synthesis of Ia molecules in microglia. In addition, Ia antigens were localized to the cells with ultrastructural features of macrophages. Thus, Ia-expressing cells in EAE seems to play dual roles: the induction of immunological reactions during earlier stages and the participation in reparative processes during convalescence.

Oxidative stress and muscular dystrophy

Oxidative stress may be the fundamental basis of many of the structural, functional and biochemical changes characteristic of the inherited muscular dystrophies in animals and humans. The presence of by-products of oxidative damage, and the compensatory increases in cellular antioxidants, both indicate oxidative stress may be occurring in dystrophic muscle. Changes in the proportions and metabolism of cellular lipids, abnormal functions of cellular membranes, altered activity of membrane-bound enzymes such as the SR Ca2+-ATPase, disturbances in cellular protein turnover and energy production and a variety of other changes all indicate that these inherited muscular dystrophies appear more like the results of oxidative stress to muscle than any other type of underlying muscle disturbance. Particular details of these altered characteristics of dystrophic muscle, in combination with current knowledge on the processes of oxidative damage to cells, may provide some insight into the underlying biochemical defect responsible for the disease, as well as direct research towards the ultimate goal of an effective treatment.

Monoclonal antibody analysis of mononuclear cells in myopathies. V: Identification and quantitation of T8+ cytotoxic and T8+ suppressor cells

In polymyositis (PM) and inclusion body myositis (IBM), but not in dermatomyositis there is evidence of cell-mediated cytotoxicity: T8+ cells accompanied by macrophages focally surround, invade, and destroy nonnecrotic muscle fibers. However, the T8 marker appears on both cytotoxic (Tc) and suppressor (Ts) cells. The Leu-15 marker appears on Ts but not on Tc cells, but it also appears on macrophages and on some killer/natural killer cells. To obviate this problem, the T8, Leu-15, and Leu-7 markers were demonstrated by sequential paired immunofluorescence in single cryostat sections. Using this approach, we reliably differentiated for the first time between Tc and Ts cells in tissue sections. Six cell phenotypes were identified: T8+ Leu-15-Leu7- Tc cells, T8+ Leu-15+ Leu-7- Ts cells, three types of Leu-7+ killer/natural killer cells, and T8-Leu-15+ Leu-7- macrophages. Muscle specimens from 5 patients with PM and 5 with IBM were studied. In each case, 6 nonnecrotic muscle fibers focally surrounded and invaded by mononuclear cells were selected randomly. A total of 2,022 mononuclear cells were analyzed, 870 from patients with PM and 1,152 from those with IBM. When counts of the identified cell phenotypes in individual patients were pooled, there were four times as many T8+ Leu-15- Leu-7- Tc cells as T8+ Leu-15+ Leu-7- Ts cells in either PM or IBM samples. However, when the relative frequencies of the Tc and Ts cells were examined in individual patients, the Tc cells tended to become more abundant, and the Ts cells correspondingly less abundant, with the duration of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Monoclonal antibody analysis of mononuclear cells in myopathies. IV: Cell-mediated cytotoxicity and muscle fiber necrosis

Cell-mediated muscle fiber injury occurs in inclusion body myositis (IBM), polymyositis (PM), and even in Duchenne dystrophy (DD). Most of the autoaggressive cells are T cells and macrophages, but some are killer/natural killer (K/NK) cells. We here compare the frequencies per 1,000 muscle fibers of endomysial K/NK cells of varying cytotoxicity with those of T cells and macrophages in 8 cases each of IBM, PM, and DD. Two-micrometer serial cryostat sections were analyzed. The Leu-4 marker, present on all T cells and some K/NK cells, and the Leu-7 and Leu-11 markers, present on K/NK cells, were localized by paired immunofluorescence. Macrophages were demonstrated by the acid phosphatase reaction. In IBM, PM and DD, the respective average cell counts per 1,000 muscle fibers were: Leu-4+7- cells (T cells not expressing a K/NK marker)--710, 530, and 59; Leu-4+7+ cells (K/NK cells of low K/NK cytotoxicity)--294, 163, and 13; Leu-4-7+ cells (K/NK cells of intermediate cytotoxicity)--32, 10, and 2; and macrophages--292, 251, and 38. Leu-11+ K/NK cells that have the highest killing activity were virtually absent in all cases. The data suggest a limited role for antigen and major histocompatibility complex unrestricted K/NK cells, as compared with antigen-specific and major histocompatibility complex-restricted T cells, in IBM and PM. Further, the findings cast doubt on the significance of either T cells or K/NK cells in mature muscle in DD.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of immunoreactive major histocompatibility complex products in human skeletal muscles

Immunoreactive class 1 and class 2 major histocompatibility complex gene products (MHCP) and beta 2 microglobulin (beta 2 MG) were demonstrated by microscopic immunocytochemistry in cryostat sections of skeletal muscle biopsies of 67 patients with various neuromuscular diseases. Diagnoses included normal muscle, chronic partial denervation, Duchenne dystrophy, polymyositis, dermatomyositis, inclusion body myositis, and miscellaneous neuromuscular diseases. Normal mature muscle fibers did not express MHCP, but blood vessels showed both class 1 and 2 MHCP and beta 2 MG. Regenerating muscle fibers showed consistent sarcolemmal class 1 MHCP expression irrespective of the disease. In polymyositis, the majority of extrafusal muscle fibers of most patients showed strong sarcolemmal class 1 MHCP expression. In dermatomyositis, muscle fibers situated either in perifascicular or in randomly clustered distribution revealed strong class 1 MHCP reactivity. In inclusion body myositis, scattered small clusters of muscle fibers were positive for class 1 MHCP. In polymyositis and inclusion body myositis, particularly strong class 1 MHCP expression was invariably seen in nonnecrotic muscle fibers partially invaded by lymphocytes whose cytotoxic effects are believed to be class 1 MHCP restricted. Factors or agents that trigger class 1 MHCP expression are presumed also to sensitize lymphocytes to muscle fibers in these diseases, but their identity remains obscure at this time. In dermatomyositis, the expression of MHCP in perifascicular muscle fibers and in areas of capillary loss may represent the triggering of MHCP expression by a nonspecific cellular stress reaction, in this case probably low-grade ischemia.

Cellular infiltrates in human skeletal muscle: exercise induced damage as a model for inflammatory muscle disease?

The type and distribution of mononuclear cell infiltrates in muscle biopsies taken from 9 subjects at differing times after exercise in which the muscle is stretched (eccentric exercise) has been characterised. The appearances are compared to those seen in muscle from patients with inflammatory muscle disease. After exercise infiltrating cells were seen in perivascular, perimysial and endomysial regions, the extent being greater in the later biopsies (9-14 days). The predominant cell type was the macrophage (46-100% of all infiltrating cells), the remainder were T lymphocytes with a predominance of the CD4 positive helper/inducer subset. Approximately one third of the T cells expressed DA2 (class 2) antigen indicating that they were activated. Very few B lymphocytes and no Leu7 positive cells were seen. There was evidence of class 1 expression on some of the damaged muscle fibres. The appearance of the experimentally damaged muscle in normal subjects was very similar to untreated polymyositis suggesting that a proportion of the infiltrating cells seen in this disease may be present as part of a natural response to damage rather than being its cause.

[Dermatopolymyositis: evaluation of 63 patients]

Sixty-three patients with dermatopolymyositis were evaluated from the clinical, laboratory and therapeutical aspects during a period of 15 years: 39 are women and 24 men. The mean age was 36.8 +/- 15.6 years. No correlation was observed between clinical and isolated therapeutics employed; when corticosteroids and cytolytic drugs were used simultaneously, the clinical response was satisfactory. No special fact was seen that can predict the therapeutical response.

The nature of host tissue destruction in tumor invasion. An experimental investigation on carcinoma and sarcoma xenotransplants

The nature of host tissue destruction in tumor invasion was investigated in experimentally induced carcinomas and sarcomas, xenografted into skeletal muscle. By means of light and electron microscopy it was shown that in both carcinomas and sarcomas the confrontation of host tissue with the invading tumor cells does not result in immediate destruction of host tissue but in a transitory state of coexistence which gradually proceeds to progressive host tissue atrophy. This process of progressive atrophy, which finally results in the total disappearance of the invaded host tissue, is considered to be caused mainly by the increasing pressure and competitive withdrawal of oxygen and nutrients by the invading and proliferating tumor cells. Morphological changes suggesting an active enzymatic breakdown of host tissue cells by tumor cells were not observed during any stage of tumor invasion.

Mononuclear cells in myopathies: quantitation of functionally distinct subsets, recognition of antigen-specific cell-mediated cytotoxicity in some diseases, and implications for the pathogenesis of the different inflammatory myopathies

Monoclonal antibodies reactive for B cells, T cells, T-cell subsets, killer (K) and natural killer (NK) cells, and the Ia antigen were used to analyze mononuclear cell subsets in scleroderma (SD), dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM), Duchenne dystrophy (DD), and normal muscle. The analysis, which was quantitative, was performed according to diagnosis and site of accumulation. Cells at perivascular, perimysial, and endomysial sites of accumulation, and cells focally surrounding and invading nonnecrotic muscle fibers, were analyzed separately. Individual antigens were localized in 2-micron serial sections, or multiple antigens were demonstrated in a given section by sequential paired immunofluorescence. The latter approach allowed the identification of the cell phenotypes in which functional properties are defined by multiple markers, e.g., T8+ and T4+ cells that are either activated or not activated, T8+ cells that are either cytotoxic or suppressor T cells, and K/NK cells of varying maturity and killing capability. The interactions of inflammatory cells of various types with each other and the muscle fiber were further investigated by immunoelectron microscopy. In SD, the findings provide evidence for a cell-mediated immune effector response against a connective tissue and/or vascular element. In DM, the effector response appears to be predominantly humoral. In PM and IBM (but not in DM or SD), there is invasion and destruction of nonnecrotic muscle fibers by cytotoxic T cells, with or without accompanying macrophages. Because T-cell-mediated injury is antigen- and major histocompatibility complex-restricted, clones of T cells must have been sensitized previously to a muscle fiber-associated surface antigen. The identity of the putative antigen(s) remains an important, unsolved question.