Israel Medical Association Journal

High mobility group box 1 is a nuclear protein participating in chromatin architecture and transcriptional regulation. When released from cells, HMGB1[1] can also act as a pro-inflammatory mediator or alarmin. Upon stimulation with lipopolysaccharides or tumor necrosis factor-alpha, HMGB1 is secreted from certain cells such as monocytes/macrophages and fosters inflammatory responses. In addition, HMGB1 is passively released from necrotic cells and mediates inflammation and immune activation. In contrast, during apoptotic cell death, nuclear HMGB1 gets tightly attached to hypo-acetylated chromatin and is not released into the extracellular milieu, thereby preventing an inflammatory response. There is accumulating evidence that extracellular HMGB1 contributes to the pathogenesis of many inflammatory diseases, including autoimmune diseases. Increased concentrations of HMGB1 have been detected in the synovial fluid of patients with rheumatoid arthritis. In animal models of RA[2], HMGB1 appears to be crucially involved in the pathogenesis of arthritis, since neutralization of HMGB1 significantly ameliorates the disease. Also, in the serum and plasma of patients with systemic lupus erythematosus we detected substantial amounts of HMGB1, which may contribute to the disease process. However, investigations of blood concentrations of HMGB1 and its relevance in human diseases are hindered by the lack of reliable routine test systems.

Medical screening is not a tangible existent tool in autoimmune disorders as it is in other illnesses. Numerous attempts are made to identify individuals destined to develop an autoimmune disease, including analysis of the genetic background, which along with the immunological profile, may assist in identifying those individuals. If these efforts turn out to be successful they may lead to the possibility of proactive measures that might prevent the emergence of such disorders. This review will summarize the attempts made to pursue autoantibodies specific for the central nervous system as potential predictors of autoimmune neurological disorders.

Treatment of vasculitides has progressed markedly over the past few decades. Recent therapeutic strategies in severe and refractory anti-neutrophil cytoplasmic antibodies-associated vasculitides include immunomodulating methods (e.g., plasma exchanges), products (such as intravenous immunoglobulins) and, more recently, new agents called biotherapies. Some of them (e.g., anti-tumor necrosis factor-alpha and anti-CD20 monoclonal antibodies) have achieved promising results and are now often used to treat severe cases.

Objectives: To describe patients with initially misdiagnosed PTP[1] and to emphasize the diagnostic pitfalls of this disorder.

Patients and Results: During a period of 11 years we have diagnosed six patients with PTP, four women and two men. The incidence of PTP was approximately 1:24,000 blood components transfused. We present the detailed clinical course of three of the six patients in whom the diagnosis was particularly challenging. The patients were initially misdiagnosed as having heparin-induced thrombocytopenia, systemic lupus erythematosus complicated by autoimmune thrombocytopenia, and disseminated intravascular coagulation. A history of recent blood transfusion raised the suspicion of PTP and the diagnosis was confirmed by appropriate laboratory workup.

Conclusions: PTP seems to be more frequent than previously described. The diagnosis should be considered in the evaluation of life threatening thrombocytopenia in both men and women with a recent history of blood transfusion.