A Review of Azathioprine-Associated Hepatotoxicity and Myelosuppression in Myasthenia Gravis.

OBJECTIVES: Myasthenia gravis (MG) is an autoimmune disorder in which antibodies interfere with neuromuscular transmission. Azathioprine (AZA) is an immunosuppressant frequently used for treatment of various autoimmune conditions, including MG. The literature suggests that the rates of AZA-associated hepatotoxicity and myelosuppression in MG are highly variable. Published studies have not formally analyzed their pattern, severity, timing, and/or recovery. We assessed the prevalence, pattern and timing of AZA associated toxicity in a large group of MG patients. METHODS: We identified 113 patients with MG with AZA-associated toxicity among 571 managed with this immunosuppressant. The timing of when toxicities occurred as well as pattern of laboratory abnormalities was assessed. RESULTS: The overall prevalence of hepatotoxicity and myelosuppression was 15.2% and 9.1%, respectively. The most common pattern of hepatotoxicity seen was gamma-glutamyl transpeptidase (GGT) enzyme elevation in 67.8% of patients. Of note, 21.2% of patients with myelosuppression had normocytic anemia, 17.3% had pancytopenia, and another 17.3% developed macrocytic anemia. CONCLUSIONS: AZA-associated hepatotoxicity and myelosuppression in MG are not uncommon and may be underrecognized depending on the timing, frequency, and specific tests ordered for blood work monitoring.

A case of good syndrome presumed secondary to metastatic pancreatic thymoma in a patient presenting with a myasthenic crisis postthymectomy.

INTRODUCTION: Myasthenia gravis (MG) is an autoimmune disorder characterized by autoantibodies against the postsynaptic nicotinic acetylcholine receptors, muscle-specific tyrosine kinase, low-density lipoprotein receptor-related protein 4, and agrin. The incidence of thymoma in MG is reported as ∼10%-15%. The incidence of extrathoracic metastatic thymoma is exceedingly rare and may present years after resection. Associations between thymoma and immunodeficiency have also been described, including Good syndrome. METHODS AND RESULTS: We describe the clinical course, investigations, and treatments performed in a patient presenting with a myasthenic crisis in the setting of acetylcholine receptor antibody-positive generalized MG 10 years postthymectomy. Computed tomography imaging revealed 2 pancreatic lesions, but no residual thoracic thymoma. Biopsy confirmed metastatic pancreatic thymoma, which was successfully resected. His course was further complicated by cytomegalovirus retinitis with a depressed CD4 count and perniosis. DISCUSSION: This presentation was felt to be consistent with Good immunodeficiency syndrome.

Epidermal 'alarm substance' cells of fishes maintained by non-alarm functions: possible defence against pathogens, parasites and UVB radiation.

Many fishes possess specialized epidermal cells that are ruptured by the teeth of predators, thus reliably indicating the presence of an actively foraging predator. Understanding the evolution of these cells has intrigued evolutionary ecologists because the release of these alarm chemicals is not voluntary. Here, we show that predation pressure does not influence alarm cell production in fishes. Alarm cell production is stimulated by exposure to skin-penetrating pathogens (water moulds: Saprolegnia ferax and Saprolegnia parasitica), skin-penetrating parasites (larval trematodes: Teleorchis sp. and Uvulifer sp.) and correlated with exposure to UV radiation. Suppression of the immune system with environmentally relevant levels of Cd inhibits alarm cell production of fishes challenged with Saprolegnia. These data are the first evidence that alarm substance cells have an immune function against ubiquitous environmental challenges to epidermal integrity. Our results indicate that these specialized cells arose and are maintained by natural selection owing to selfish benefits unrelated to predator-prey interactions. Cell contents released when these cells are damaged in predator attacks have secondarily acquired an ecological role as alarm cues because selection favours receivers to detect and respond adaptively to public information about predation.