Question: What medication, used as chemotherapy and to suppress the immune system, is used as treatment for Autoimmune encephalitis?

 Associated with systemic autoimmune disorders, CNS autoimmune disorders and paraneoplastic syndromes.  Pathogenesis is likely to be mediated by antibodies (Abs) to CNS proteins. Autoimmune encephalitis (or autoimmune encephalopathy) is a diverse group of neuro-psychiatric disorders recognized recently , presenting acutely or subacutely with alteration of consciousness, cognitive decline, seizure, and abnormal movements.  The Abs are directed against membrane receptors and ion channel-associated proteins that are expressed on the surface of neurons in the CNS, such as N-methyl D-aspartate receptors and leucine-rich, glioma inactivated protein and contactin-associated protein like, that are associated with voltage-gated potassium channels.  The diseases are not invariably cancer-related and are therefore different from the classical paraneoplastic neurological diseases that are associated with, but not caused by, Abs to intracellular proteins.  Diagnosis of autoimmune encephalopathy is based on the clinical course, serologic evidence of autoimmunity, severe but nonspecific slowing on electroencephalography, and evidence of intrathecal inflammation in the cerebrospinal fluid and neuroimaging by MRI.  Treatment include first-line steroids, intravenous immunoglobulins (IVIG), and plasma exchange, and second-line Rituximab and Cyclophosphamide, followed in many cases by steroid-sparing agents in the long-term. <SEP> Biological response modifiers (BRMs) are substances that modify immune responses.  They can be both endogenous (produced naturally within the body) and exogenous (as pharmaceutical drugs), and they can either enhance an immune response or suppress it.  Some of these substances arouse the body's response to an infection, and others can keep the response from becoming excessive.  Thus they serve as immunomodulators in immunotherapy (therapy that makes use of immune responses), which can be helpful in treating cancer (where targeted therapy often relies on the immune system being used to attack cancer cells) and in treating autoimmune diseases (in which the immune system attacks the self), such as some kinds of arthritis and dermatitis.  Most BRMs are biopharmaceuticals (biologics), including monoclonal antibodies, interleukin 2, interferons, and various types of colony-stimulating factors (e.g., CSF, GM-CSF, G-CSF).  "Immunotherapy makes use of BRMs to "enhance" the activity of the immune system to increase the body's natural defense mechanisms against cancer", whereas BRMs for rheumatoid arthritis aim to reduce inflammation. <SEP> Immunomics is the study of immune system regulation and response to pathogens using genome-wide approaches.  With the rise of genomic and proteomic technologies, scientists have been able to visualize biological networks and infer interrelationships between genes and/or proteins; recently, these technologies have been used to help better understand how the immune system functions and how it is regulated.  Two thirds of the genome is active in one or more immune cell types and less than 1% of genes are uniquely expressed in a given type of cell.  Therefore, it is critical that the expression patterns of these immune cell types be deciphered in the context of a network, and not as an individual, so that their roles be correctly characterized and related to one another.  Defects of the immune system such as autoimmune diseases, immunodeficiency, and malignancies can benefit from genomic insights on pathological processes.  For example, analyzing the systematic variation of gene expression can relate these patterns with specific diseases and gene networks important for immune functions. <SEP>  As chemotherapy it is used to treat lymphoma, multiple myeloma, leukemia, ovarian cancer, breast cancer, small cell lung cancer, neuroblastoma, and sarcoma. Cyclophosphamide (CP), also known as cytophosphane among other, is a medication used as chemotherapy and to suppress the immune system.  As an immune suppressor it is used in nephrotic syndrome and following organ transplant.  It is taken by mouth or injection into a vein.