The International Panel on MS Diagnosis presents revised diagnostic criteria for multiple sclerosis (MS). The focus remains on the objective demonstration of dissemination of lesions in both time and space. Magnetic resonance imaging is integrated with clinical and other paraclinical diagnostic methods. The revised criteria facilitate the diagnosis of MS in patients with a variety of presentations, including "monosymptomatic" disease suggestive of MS, disease with a typical relapsingremitting course, and disease with insidious progression, without clear attacks and remissions. Previously used terms such as "clinically definite" and "probable MS" are no longer recommended. The outcome of a diagnostic evaluation is either MS, "possible MS" (for those at risk for MS, but for whom diagnostic evaluation is equivocal), or "not MS."
Apoptosis of mature T lymphocytes preserves peripheral homeostasis and tolerance by countering the profound changes in the number and types of T cells stimulated by diverse antigens. T cell apoptosis occurs in at least two major forms: antigen-driven and lymphokine withdrawal. These forms of death are controlled in response to local levels of IL-2 and antigen in a feedback mechanism termed propriocidal regulation. Active antigen-driven death is mediated by the expression of death cytokines such as FasL and TNF. These death cytokines engage specific receptors that assemble caspase-activating protein complexes. These signaling complexes tightly regulate cell death but are vulnerable to inherited defects. Passive lymphokine withdrawal death may result from the cytoplasmic activation of caspases that is regulated by mitochondria and the Bcl-2 protein. The human disease, Autoimmune Lymphoproliferative Syndrome (ALPS) is due to dominant-interfering mutations in the Fas/APO-1/CD95 receptor and other components of the death pathway. The study of ALPS patients reveals the necessity of apoptosis for preventing autoimmunity and allows the genetic investigation of apoptosis in humans. Immunological, cellular, and molecular evidence indicates that throughout the life of a T cell, apoptosis may be evoked in excessive, harmful, or useless clonotypes to preserve a healthy and balanced immune system.
Understanding of autoimmune diseases, including multiple sclerosis, has expanded considerably in recent years. New insights have been provided by not only animal models but also studies of patients, often in conjunction with experimental therapies. It is accepted that autoimmune T cells mediate the early steps of new multiple sclerosis lesions, and although uncertainties remain about the specific targets of autoreactive T cells, several studies indicate myelin antigens. Recent findings obtained with both animal models and patients with multiple sclerosis indicate involvement of a T helper cell with a T(H)-17 phenotype, in contrast to previous data indicating that T helper type 1 cells are critical. Evidence has also been presented for CD8(+) and regulatory T cell populations, although their involvement remains to be established. Despite evidence supporting the idea that autoreactive T cells are involved in disease induction, cells of myeloid lineage, antibodies and complement as well as processes intrinsic to the central nervous system seem to determine the effector stages of tissue damage. Careful analysis of the alterations in immune processes should further advance knowledge of the relationship between the inflammatory component of this disease and the more diffuse degeneration of progressive multiple sclerosis.
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