Clin Exp Immunol 1994; 95:166- 172

MHC class I, MHC class II and intercellular adhesion molecule-1 (ICAM-1)

expression in inflammatory myopathies

E. BARTOCCIONI, S. GALLUCCI, F. SCUDERI, E. RICCI*, S. SERVIDEI*, A. BROCCOLINI* &

P. TONALI* Institute of General Pathology and *Institute of Neurology, Catholic University, Rome, Italy

(Acceptedfor publication 9 August 1993)

SUMMARY

We investigated the relationship between the MHC-I, MHC-II and intercellular adhesion molecule- I(ICAM- 1) expression on myofibres and the presence of inflammatory cells in muscle specimens of 18patients with inflammatory myopathies (nine polymyositis, seven dermatomyositis, two inclusionbody myositis). We observed MHC-I expression in muscle fibres, infiltrating mononuclear cells andendothelial cells in every specimen. In seven patients, some muscle fibres were MHC-II-positive forthe DR antigen, while the DP and DQ antigens were absent. ICAM-1 expression, detected in seven

patients, was found in clusters of myofibres, associated with a marked MHC-I positivity and a

widespread mononuclear infiltration. Most of the ICAM-l-positive fibres were regenerating fibres.Furthermore, some fibres expressed both ICAM-1 and DR antigens near infiltrating cells. Thisfinding could support the hypothesis that myofibres may themselves be the site of autosensitization.

Keywords adhesion molecules inflammatory myopathies MHC-I MHC-II ICAM-1

INTRODUCTION

Some idiopathic inflammatory myopathies are currently sup-

posed to be of autoimmune origin [1]. Several immunohisto-chemical studies have provided evidence of a T cell-mediatedcytotoxic reaction against muscle fibres in polymyositis (PM)and inclusion body myositis (IBM), and of an antibody- or

immune complex-mediated reaction against a vascular factor indermatomyositis (DM) [2,3]. Furthermore, cytotoxic T cells,isolated and cultured from the muscle of patients with inflam-matory myopathies, have shown cytotoxicity against autolo-gous myotubes [4].

MHC-I expression on target cells is a prerequisite forantigen-specific T cell-mediated cytotoxicity [5]. It is known thatMHC-I antigen is absent from the sarcolemma of normalmuscle fibres [2,6]. Previous studies [2,7-10] have shown thatmyofibres can express MHC-I in PM, IBM and DM, but theresults concerning the extent and distribution of MHC-Iexpression are conflicting. On the other hand, MHC-II ex-

pression on antigen-presenting cells (APC) is necessary to

activate T helper lymphocytes and to initiate an immuneresponse; some evidence suggests that myofibres may behave as

APC. MHC II antigen has not been found on normal myofibres[11], in contrast to myoblasts in culture [12], that have beenshown to behave as APC [13]; some authors [14,151 have

detected DR antigen on muscle fibre membranes in PM and

DM, while other authors [8,10] did not find it.

Correspondence: Dr Emanuela Bartoccioni, Institute of GeneralPathology, Catholic University, 1, Largo Francesco Vito, 00168 Rome,Italy.

MHC-I- and MHC-II-dependent processes require theexpression of intercellular adhesion molecule-l (ICAM-l). Thismolecule is necessary to stabilize the interactions between the Tcell receptor and MHC-peptide complex in antigen recognition.In fact, it has been demonstrated that in vitro the T cell killingmay be blocked with antibody to ICAM-1 [16,17] and that thetransfection with the gene encoding ICAM-l enabled fibro-blasts expressing suboptimal levels of MHC molecules toactivate T helper cells [18]. It has also been shown that cytokineswere able to induce ICAM- I expression on myoblasts in culture[13].

Fig. 1. Control muscle specimens. (a) Leu-19 expression is very weak on

satellite cells (arrows). (b) MHC-I expression on vascular endothelialcells. (c) DR expression on vascular endothelial cells. (d) Very weakICAM- 1 expression on some vascular endothelial cells. Immunoperoxi-dase staining, x 250.

Fig. 2. Serial sections from a polymyositis (PM) patient musclespecimen. (a) Haematoxylin-eosin. (b, c, d) Immunoperoxidase stain-ing, x 250. (a) Mononuclear cell infiltration. (b) Leu- 19 expression. Leu-19 positivity is present on membranes and/or internally in regeneratingcells. (c) MHC-I expression. MHC-I antigen on myofibres, endothelialand infiltrating mononuclear cells is shown. This is detected not only onthe plasma membrane but also internally in some more strongly invadedmyofibres. (d) DR expression. DR antigen is expressed on myofibres,endothelial and infiltrating mononuclear cells. Some myofibres showedDR antigen both on membranes and internally where the pattern was

reticular (*)

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Muscle fibre regeneration is a common phenomenon ininflammatory myopathies. Regenerating fibres can be stainedby MoAb anti-Leu-19 which recognizes the CD56 differentia-tion antigen: this is a glycoprotein shared by natural killer (NK)cells, satellite cells in normal muscle and developing muscle cellsin culture [19-21]. Furthermore, it has been shown thatantibodies to Leu-19 and neural cell adhesion molecule (N-CAM) recognize the same muscle-specific glycoproteins,expressed also by neural and endocrine cells [19,20,22].

In the muscle the Leu-19 molecule may play a role ininnervation, in muscle-nerve interaction, and in muscle de-velopment [19,23]. Moreover, it has been hypothesized that thisantigen could behave as an adhesion molecule in NK-target cellinteraction [20].

It is possible that myofibres and myoblasts express adhesionmolecules in different ways, and play distinct roles in thepathogenesis of inflammatory myopathies.

The objectives of this study were to reinvestigate thedistribution of MHC-I and MHC-II expression on myofibresand regenerating fibres, to look for ICAM-1 expression on

muscle cells, and to identify a possible relationship betweenMHC-I, MHC-II and ICAM-l expression and the presence ofinflammatory cells in muscle specimens of patients with inflam-matory myopathies.

MATERIALS AND METHODS

Sources of muscleMuscle specimens were taken from 27 subjects with thefollowing diagnoses: nine patients with polymyositis, seven

patients with dermatomyositis, two patients with inclusion bodymyositis, one patient with myasthenia gravis as pathologicalcontrol, and eight adult normal controls (age-matched withpatients) showing no clinical or microscopic abnormality.Frozen blocks of biopsied skeletal muscles were used; some ofthe tissue had been kept at -I 00°C for up to 4 years before use.

The patients' diagnoses were established on the basis of theusual clinical criteria and appropriate laboratory data: electro-myographic studies showing myopathic potentials, elevatedserum creatine kinase levels and microscopic evaluation ofmuscle biopsies.

ImmunoreagentsSerial sections were stained with or reacted for the following:mouse MoAb IgGl anti-ICAM-1 (clone 84H10) and mouse

MoAb IgG2a kappa anti-HLA A, B, C antibody (cloneB9.12.1) (Immunotech S.A, Marseille, France); mouse MoAbIgG2a anti-DR (clone L243), mouse MoAb IgG1 anti-DP(clone B7/21), mouse MoAb IgGl anti-DQ (clone SK10)(Becton Dickinson, San Jose, CA); mouse MoAb IgGI anti-

Leu-19 (clone MY31; Becton Dickinson); mouse MoAb IgGIanti-fast myosin (clone MY32) used as positive control and

purified mouse IgG (at the same concentration of MoAb) as

negative control (Sigma ImmunoChemicals, St Louis, MO);each sequence of sections included one slice stained with

haematoxylin-eosin. The reaction of the first antibody was

revealed using a commercial kit (Vectastain ABC Kit; Vector

Labs, Burlingame, CA), following the kit instructions.

Immunoperoxidase procedureSerial 5-pm thick sections were prepared from each block in

duplicate and mounted on electrostatic slides (Histostat, Men-

zel-Glaser, Genova, Italy). The sections were fixed for 10 min inacetone at - 20°C. After rinsing in Tris-buffered saline (TBS)for 5 min, hydrogen peroxide 3% was used to inhibit theendogenous peroxidases. After two rinses in TBS of 5 min each,a normal horse serum (NHS) (Vector Labs) was applied for 10min to block non-specific binding; after removal of the excess ofNHS, MoAb, biotinylated anti-mouse immunoglobulin anti-body and an avidin-biotinylated horseradish peroxidase macro-molecular complex were applied at room temperature for 30 mineach, with two rinses of 5 min in TBS between each. Finally, a

solution of equal volumes of diaminobenzidine tetrahydro-chloride (DAB) 0-1% in TBS, and hydrogen peroxide 0-015% indistilled water, was applied for 7-8 min and washed with tapwater.

The intensity of the stain on inflammatory cells, bloodvessels and muscle fibres was evaluated subjectively on a scale of- to + ++ (-, absent; +, distinct but poorly stained; + +,

distinct; + ++, marked). The expression of immunoreactiveproteins was correlated with conventional pathological changesand the extent of the mononuclear infiltration in muscle fibres(scale of 0 to 3) as displayed by the haematoxylin-eosin stain.

RESULTS

In control muscles all the antigens studied were absent from thesurface of muscle fibres, while MHC-I, DP, DQ and DR

Table 1. MHC-I, DR, intercellular adhesion molecule-I (ICAM-1)expression and myopathy signs in the 18 patients studied

Patient Myopathy signs MHC-I DR ICAM-1

Polymyositis1 2 D++ - -2 3 D++ - F+3 1 F+ - -4 2 D++ - -5 3 D+++ F++ -6 3 D+++ F++ F+7 2 D+++ F++ F+8 1 D++ -F+9 1 F++ - -

Dermatomyositis1 2 D+ + + F+ F+2 2 D++ - -3 1 F+4 2 D+++ F+ + F+5 1 D++ - -6 2 D+ - -7 1 D+ - -

Inclusion body myositis1 1 F+ F+ F+2 1 D+ F+ -

The intensity ofmyopathy signs are evaluated from 1 to 3 (1, weak; 2,moderate; 3, severe). The intensity of the stain was evaluated subject-ively on a scale of + to + + + (+, distinct but poorly stained; + +,distinct; + + +, marked). -, Positivity is absent; D, positivity is presenton every myofibre (diffusely); F, positivity is present on single or clustersof myofibres (focally).

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d

Fig. 3. Serial sections from two polymyositis (PM) patients' muscle specimens. (a) Leu- 19 expression. (b) MHC-I expression in one

patient. (c) Leu-19 expression. (d) MHC-II expression in the other patient. Immunoperoxidase staining, x 250. (a, b) Leu-19-positive

cells ('9 show a strong positivity (+++ +) for MHC-I antigen, while most Leu- 19-negative cells (arrows) are weakly positive (+) for the

same antigen. (c, d) Leu- 19 expression is restricted to satellite cells (arrow); DR antigen is expressed on the membrane of Leu- 19-

negative myofibres (A&) with intensity ranging from (+) to (+ +). Endothelial cells are also DR-positive (arrowhead).

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Fig. 4. Serial sections from a polymyositis (PM) patient muscle specimen, x 400. (a) Mononuclear infiltration with necrotic myofibres

undergoing phagocytosis. Haematoxylin-eosin. (b) ICAM- positivity is present on the surface and internally with a reticular pattern in

a single myofibre (*) morphologically normal on H&E staining (a). Immunoperoxidase staining.

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antigens were expressed on vascular endothelial cells, and Leu-19 antigen was present on a small number of satellite cells.ICAM- 1 antigen was very weakly (+) expressed on somevascular endothelial cells (Fig. 1).

In Table 1 MHC-I, DR, ICAM- 1 -positivities and pathologi-cal features in the patients studied are summarized.

Distribution of Leu-J9 immunoreactivityIn the specimens from patients with DM, PM and IBM, Leu-19-positive regenerating fibres were present either scattered or insmall groups with intensity ranging from (+) to (+ + +). Theirpresence was significantly higher in patients with severe mono-nuclear cell infiltration or necrosis. When stained with haema-toxylin-eosin, many Leu- 19-positive cells appeared as smallbasophilic fibres, while some appeared normal and a few aseosinophilic invaded fibres. Infiltrating mononuclear cells wereLeu-19-negative (Fig. 2a, b).

Distribution of MHC-I immunoreactivityIn the DM, PM and IBM sections, we observed MHC-Iexpression in normal and regenerating muscle fibres, in infiltrat-ing mononuclear cells and in endothelial cells in all specimens.MHC-I expression was detected on the surface membrane; thestrongly positive fibres (+ + +) also showed a reticular patternof internal reactivity (Fig. 2c). In most cases every fibre wasMHC-I-positive, whilst in one DM, in one IBM and in two PMpatients the MHC-I expression was present only in clusters offibres. It is noteworthy that both IBM subjects showed weakMHC-I expression (+). Leu-1 9-positive cells generallyexpressed MHC-I antigen, often more intensely (MHC-I inten-sity: + + to + + +) than Leu-19-negative fibres (MHC-Iintensity: + to + +) (Fig. 2b, c; Fig. 3a, b). In all specimenswhere a severe inflammatory infiltrate was present, the intensityof MHC-I was marked (+ + +), particularly on the invadedfibres and the cells invading them; in contrast, in specimens inwhich infiltration and evidence of myopathy were scarce, as inboth IBM subjects, the intensity was weak (+) and in somecases was distributed focally.

Distribution of MHC-I! immunoreactivityIn 3/9 PM, 2/7 DM and 2/2 IBM patients some muscle fibreswere MHC-II positive for the DR antigen, with intensitiesranging from (+) to (+ +). The DP and DQ antigens wereabsent. DR expression was present in clusters of fibres and wasrelated to the amount of infiltrating cells within the fascicles.DR-positive fibres were mostly positioned near strongly DR-positive infiltrating cells (Fig. 2a, d). Most of the fibres bearingthe DR antigen were Leu-19-positive (Fig. 2b, d), but the DRantigen was also present on quiescent non-regenerating fibres,even where infiltrates were sparse (Fig. 3c, d).

DR-positive muscle fibres showed a strong MHC-I intensity(+ + +) in PM and DM (Fig. 2c, d). In both IBM subjects, bycontrast, the MHC-I expression was weak (+), whereas DR wasrelatively strong, even though the infiltrates were sparse.

Distribution of ICAM-J immunoreactivityMononuclear cells and endothelial cells expressed ICAM-1weakly (+) in all the specimens studied (Fig. ld). ICAM-lexpression on myofibres was detected in 4/9 PM, 2/7 DM and 1/2 IBM. ICAM-1 expression (intensity ranging from + to + +)was found in clusters of fibres and was usually present on the

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Fig. 5. Serial sections from a dermatomyositis (DM) patient musclespecimen. (a) Haematoxylin-eosin. (b) MHC-I expression, immunoper-oxidase. (c) ICAM- 1 expression, immunoperoxidase, x 250. It is evidentthat one ICAM- I -positive myofibre (A) is strongly MHC-I-positive andmorphologically normal at H&E staining, while the invaded (*) fibresare ICAM-l-negative.

surface membrane and, in a few cases, also in the sarcoplasm,where it was expressed patchily (Fig. 4b). All seven ICAM-1-positive specimens also showed distinct MHC-I positivity andwidespread mononuclear infiltration (Fig. 5). The ICAM-1antigen was present both on normal and regenerating fibres, butmainly on the latter. In addition, some of the ICAM-l-positivemyofibres also expressed DR and Leu-19 antigens. It isnoteworthy that invaded myofibres which showed a marked

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Adhesion molecules and inflammatory myopathies 171

expression of MHC-I generally did not express ICAM-1, butwere often close to ICAM-1-positive myofibres (Fig. 5).

DISCUSSION

This study clearly showed that in PM, IBM and DM somemyofibres, in contrast to those in healthy muscle cells, expressedICAM-1 on membranes of some cells, mostly of regeneratingfibres, and that ICAM- I -positive myofibres presented a markedMHC-I expression and were surrounded by severe mononuclearinfiltration; furthermore, it has been found that some myofibres,mainly but not exclusively regenerating fibres, expressed bothICAM- I and DR antigens, and that this also could be related tothe presence of infiltrating cells.

The prominent histological features of inflammatory myo-pathies [I] at light microscopy are proliferation ofinflammatorycells, phagocytosis, necrosis and regeneration of muscle fibres.In PM and IBM the infiltrating cells are mostly CD8 +

lymphocytes (CTL), mediating an antigen-driven cytotoxicityagainst myofibres [24], while in DM the infiltrating cells aremostly CD4+ lymphocytes (Th) producing, through a humoralmechanism, microangiopathy and muscle damage [25].

ICAM- I molecules are necessary to stabilize the interactionsbetween the T cell receptor and MHC-peptide in antigenrecognition [26] and are required for the performance of theeffector mechanisms of T cell cytotoxicity in most cell systems.These molecules, whose ligand on T cells is the lymphocytefunction associated antigen-I (LFA-1), are commonly presentnot only on professional APC such as macrophages anddendritic cells [27,28], but also on tissues involved in inflamma-tory processes [29,30]. They are absent from normal muscle and,in a recent study, have not been found in one toxic myopathy[31].

The expression of ICAM-1 is not a static process: it can bequickly modified by many factors, such as the tumour necrosisfactor (TNF) and interferon-gamma (IFN-y) cytokines, and iscell-cycle dependent. On the other hand, cytolytic T lympho-cytes (CTL), after recognizing the antigen through their T cellreceptors (TCR), increase the avidity of their own LFA-1 for theICAM- 1 ligands present on the target cell membrane. CTL canthen adhere to the target cell, deliver the lethal hit and attackanother cell. The whole process is very rapid, taking only a fewminutes. The number of ICAM-1-positive fibres that we foundwas relatively small: this finding could be explained by therapidity of the process. Alternatively, this finding could reflecteither the preferential expression at a specific moment of the cellcycle of regenerating fibres, or the length and segmental natureof mature muscle fibres, which could allow the ICAM-1expression only on some definite sites of sarcolemma: in thesections of this study, then, only some of these ICAM-1 -positivesites could be seen. Furthermore, we found that MHC-Iexpression on myofibres, which is absent in normal muscle, wasgenerally distributed on pathological specimens with a homo-geneous pattern: its presence is considered a necessary but notsufficient condition for T cell-mediated cytotoxicity in myopath-ies [2]. Therefore, the finding that the ICAM-l -positive fibreswere generally not invaded myofibres while, in PM and IBMspecimens, the invaded fibres were ICAM- 1-negative, suggeststhat the sequential ICAM-1 expression could drive the processof fibre cytolysis in these diseases and that ICAM-1 expression

on target cells is a necessary condition for T cell-mediatedcytotoxicity in myopathies.

On the other hand, ICAM-1 and MHC-I positivity in DMpatients, whose pathogenesis is considered as humoral, could bea non-specific response ofthe muscle tissue to damage caused bysubacute ischaemia [2,8].

It is interesting that ICAM- I -positive myofibres were mostlyregenerating fibres: this finding could mean that regeneratingfibres are the preferential target of cytolytic cells, frustrating theprocess of muscle repair.

In some cases of inflammatory myopathies studied, somemuscle fibres expressed both ICAM-1 and DR antigens. TheICAM- 1 and DR expression was present in fibres mostlypositioned near infiltrating cells, and was to some extent relatedto the presence of infiltrates within the fascicles; where DRexpression was present on myofibres, infiltrating cells were alsopresent. These findings could be further evidence to support thehypothesis that myofibres may themselves be the site ofautosensitization and behave as occasional APC [13].

Finally, it is noteworthy that some cytokines take part ininducing MHC-II and ICAM-I expression not only on profes-sional APC but also on other cell systems [9,13,28,32]. There-fore, such cytokines could also be involved in pathogenesis ofinflammatory myopathies.

ACKNOWLEDGMENTSThe financial support given by Telethon-Italy to the project 'In vitrocellular immunity in inflammatory myopathies: cocultures of Tlymphocytes, dendritic cells and autologous myotubes' is gratefullyacknowledged. We thank Dr Nicola Maggiano for his continuoussupport, and Dr Reinhard Hohlfeld for the critical revision ofthe paper.

REFERENCES1 Dalakas MC. Polymyositis, dermatomyositis, and inclusion-body

myositis. N Engl J Med 1991; 325:1487-98.2 Emslie-Smith AM, Arahata K, Engel AG. Major histocompatibilitycomplex class I antigen expression, immunolocalization of inter-feron subtypes, and T cell-mediated cytotoxicity in myopathies.Hum Pathol 1989; 20:224-31.

3 Emslie-Smith AM, Engel AG. Microvascular changes in early andadvanced adult dermatomyositis. Am Neurol 1990; 27:343-56.

4 Hohlfeld R, Engel AG. Coculture with autologous myotubes ofcycotoxic T cells isolated from muscle in inflammatory myopathies.Ann Neurol 1991; 29:498-507.

5 McMichael AJ. HLA restriction ofhuman cytotoxic T cell. SpringerSemin Immunopathol 1980; 3:3-22.

6 Daar AS, Fuggle SV, Fabre JW, Ting A, Morris PJ. The detaileddistribution of HLA-A, B, C antigens in normal human organs.Tranplantation 1984; 38:287-92.

7 Appleyard ST, Dunn MZ, Dubowitz V, Rose ML. Increasedexpression of HLA ABC class I antigens by muscle fibres in.Duchenne muscular dystrophy, inflammatory myopathy and otherneuromuscular disorders. Lancet 1985; i:361-3.

8 Karpati G, Pouliot Y, Carpenter S. Expression of immunoreactivemajor histocompatibility complex products in human skeletalmuscle. Ann Neurol 1988; 23:64-72.

9 Isenberg DA, Rowe D, Shearer M, Novick D, Beverley PCL.Localization of interferons and interleukin 2 in polymyositis andmuscular dystrophy. Clin Exp Immunol 1986; 63:450-8.

10 McDouall RM, Dunn MJ, Dubowitz V. Expression of class I andclass II MHC antigens in neuromuscular diseases. J Neurol Sci 1989;89:213-26.

172 E. Bartoccioni et al.

11 Daar AS, Fuggle SV, Fabre JW, Ting A, Morris PJ. The detaileddistribution ofMHC class II in normal human organs. Transplant-ation 1984; 38:293-8.

12 Cifuentes-Diaz C, Delaporte C, Dautreaux B, Charron D, FardeauM. Class II MHC antigens in normal human skeletal muscle. MuscleNerve 1992; 3:295-302.

13 Goebels N, Michaelis D, Wekerle H, Hohlfeld R. Human myoblastsas antigen-presenting cells. J Immunol 1992; 149:661-7.

14 Rowe D, Isenberg DA, Beverley PCL. Monoclonal antibodies toimmune leukocyte antigens in polymyositis and muscular dys-trophy. Clin Exp Immunol 1983; 54:327-36.

15 Olsson T, Henriksson KG, Klareskog L, Forsum U. HLA-DRexpression, T lymphocyte phenotypes, OKMl and OKT9 reactivecells in inflammatory myopathy. Muscle Nerve 1985; 8:419-25.

16 Dustin ML, Springer TA. T cell receptor cross linking transientlystimulates adhesiveness through LFA-1. Nature 1989; 341:619-24.

17 Makgoba MW. Functional evidence that intercellular adhesionmolecule-I (ICAM-1) is a ligand for LFA-l-dependent adhesion inT-cell-mediated cytotoxicity. Eur J Immunol 1988; 18:637-40.

18 Altmann DM, Hogg N, Trowsdale J, Wilkinson D. Cotransfectionof ICAM-1 and HLA-DR reconstitutes human antigen-presentingcell function in mouse 1 cells. Nature 1989; 338:512-4.

19 Schubert W, Zimmermann K, Cramer M, Starzinski-Powitz A.Lymphocyte antigen Leu- 19 as a molecular marker of regenerationin human skeletal muscle. Proc Natl Acad Sci USA 1989; 86:307-11.

20 Illa I, Leon-Monzon M, Dalakas MC. Regenerating and denervatedhuman muscle fibres and satellite cells express neural cell adhesionmolecule recognized by monoclonal antibodies to natural killer cells.Ann Neurol 1992; 31:46-52.

21 Griffin JD, Hercend T, Beveridge R, Schlossman SF. Characteriza-tion ofan antigen expressed by human natural killer cells. J Immunol1983; 130:2947-51.

22 Aletsee-Ufrecht MC, Langley OK, Gratzl M. NCAM expression

in endocrine cells. Acta Histochemica 1990; Suppl.-BandXXXVIII:S45-50.

23 Rutishauer U, Grumet M, Edelman GM. Neural cell adhesionmolecules mediate initial interactions between spinal cord neuronsand muscle cells in culture. J Cell Biol 1983; 97:145-52.

24 Engel AG, Arahata K. Monoclonal antibody analysis of mono-nuclear cells in myopathies. V: Identification and quantification ofT8 + cytotoxic and T8 + suppressor cells. Ann Neurol 1988; 23:493-9.

25 Kissel JT, Halterman RK, Rammohan KW, Mendel JR. Therelationship of complement-mediated microvasculopathy to thehistologic features and clinical duration of disease in dermato-myositis. Arch Neurol 1991; 48:26-30.

26 Springer TA. Adhesion receptors of the immune system. Nature1990; 346:425-34.

27 Patarroyo M, Prieto J, Rincon J et al. Leukocyte-cell adhesion: amolecular process fundamental in leukocyte physiology. ImmunolRev 1990; 114:67-108.

28 Dustin ML, Rothlein R, Bhan AK, Dinarello CA, Springer TA.Induction by ILl and interferon-y: tissue distribution, biochemistryand function of a natural adherence molecule (ICAM- 1). J Immunol1986; 137:245-54.

29 Volpes R, Van Den Oord JJ, Desmet VJ. Immunohistochemicalstudy ofadhesion molecules in liver inflammation. Hepatology 1990;12:59-65.

30 Weetman AP, Cohen S, Makgoba MW, Borysiewicz LK. Ex-pression of an intercellular adhesion molecule, ICAM-1, by humanthyroid cells. J Endocrinol 1989; 122:185-91.

31 Schalke BB, Schmidt B, Toyka K, Hartung HP. Pravastatin-associated inflammatory myopathy. N Engl J Med 1992; 327:649-50.

32 Rosa F, Hatat D, Abadie A et al. Regulation of histocompatibilityantigens by interferon. Ann Ist Pasteur Immunol 1986; 136:103-19.