Altered distribution of plectin/HD1 in dystrophinopathies.

Plectin/HD1 is a high molecular weight protein (approximately 500 kDa) that has been proposed to act as an important and versatile cytoskeletal cross-linker molecule. Mutations of the human plectin gene have recently been associated with the autosomal recessive disorder epidermolysis bullosa simplex with muscular dystrophy. We studied the expression of plectin/HD1 in various neuromuscular disorders by indirect immunofluorescence. In cross sections of normal human muscle, plectin/HD1 showed a checkerboard-like distribution with moderate to intense cytoplasmic and sarcolemmal staining in type 1 fibers and a faint staining of the sarcolemma in type 2 fibers. In longitudinal sections of plectin/HD1-positive fibers a cross-striation staining pattern was noted. This fiber type-related expression was significantly altered in the group of dystrophinopathies, whereas it was maintained in all other myopathies and denervating disorders. In seven dystrophinopathies studied, a markedly increased plectin/HD1 immunoreactivity at the sarcolemmal level of type 2 fibers was observed. Confocal laser microscopy of normal skeletal muscle revealed a colocalization of desmin and plectin/HD1 at the level of the sarcolemma. This suggests that plectin/HD1- in analogy to its demonstrated involvement in cytokeratin-hemidesmosome linkage in epidermis-may mediate the anchorage of desmin to the sarcolemma (i.e. to costameres).

Influence of human recombinant interferon-alpha2a (rhIFN-alpha2a) on altered lymphocyte subpopulations and monocytes in Behcet's disease.

OBJECTIVE: In Behçet's disease (BD), several abnormalities of lymphocyte subpopulations have been described. Standard treatment comprises immunosuppressive drugs. We successfully treated 50 patients with ocular BD with interferon-alpha2a (IFN-alpha2a) (response rate 92%), although this is counterintuitive because IFN-alpha is immunostimulatory and can sometimes even induce autoimmune diseases such as systemic lupus erythematosus or rheumatoid arthritis. The aim of the present study was to elucidate the immunomodulatory effects that IFN-alpha might exert on peripheral blood mononuclear cells (PBMC) in BD by examining changes in the distribution of lymphocyte subpopulations under IFN-alpha2a treatment. METHODS: Fourteen patients with ocular BD were evaluated before and at weeks 4 and 24 of IFN-alpha treatment and compared with 10 healthy controls. PBMC were stained with monoclonal antibodies and measured by flow cytometry. RESULTS: Compared with the controls there is a significant elevation of monocytes (CD14(+)), CD8(+)/gammadelta T cells, CD3(+)/gammadelta T cells, natural killer (NK) cells (CD56(+)/CD16(+)) and activated/regulatory T cells (CD4(+)/CD25(+) and CD8(+)/CD25(+)) in patients with active BD before treatment with IFN-alpha2a. Numbers of naïve T cells (CD8(+)/CD45(+)RA(+)/RO(-), CD4(+)/CD45(+)RA(+)/RO(-)) were significantly lower. Under therapy, NK cells, CD8(+)/gammadelta T cells and CD3(+)/gammadelta T cells decreased significantly, whereas B cells increased. The previously reduced expression of HLA class I on monocytes in HLA-B51-positive patients rose to levels comparable to HLA-B51-negative patients. CONCLUSION: These results implicate the participation of NK cells and gammadelta T cells, especially CD8(+)/gammadelta T cells, in the pathogenesis of BD and may explain one mechanism by which IFN-alpha2a exerts therapeutic effects. Alternatively, they may result indirectly from remission induction by IFN-alpha2a. The reduced expression of HLA class I on monocytes in HLA-B*51-positive patients might reflect an impaired expression of and antigen presentation by HLA-B*51.